US20090031044A1 - High-Speed MAC Address Search Engine - Google Patents

High-Speed MAC Address Search Engine Download PDF

Info

Publication number
US20090031044A1
US20090031044A1 US12/107,567 US10756708A US2009031044A1 US 20090031044 A1 US20090031044 A1 US 20090031044A1 US 10756708 A US10756708 A US 10756708A US 2009031044 A1 US2009031044 A1 US 2009031044A1
Authority
US
United States
Prior art keywords
address
record
computer
primary
value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/107,567
Inventor
Craig Barrack
James Ching-Shau Yik
Rong-Feng Chang
Eric Lin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ikanos Communications Inc
Original Assignee
Conexant Systems LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/643,567 external-priority patent/US6697873B1/en
Application filed by Conexant Systems LLC filed Critical Conexant Systems LLC
Priority to US12/107,567 priority Critical patent/US20090031044A1/en
Assigned to ZARLINK SEMICONDUCTOR V.N. INC. reassignment ZARLINK SEMICONDUCTOR V.N. INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BARRACK, CRAIG, YIK, JAMES CHING-SHAU, CHANG, RONG-FENG, LIN, ERIC (A.K.A. CHANGHWA)
Assigned to ZARLINK SEMICONDUCTOR INC. reassignment ZARLINK SEMICONDUCTOR INC. CONFIRMATORY ASSIGNMENT Assignors: ZARLINK SEMICONDUCTOR V.N. INC.
Assigned to CONEXANT SYSTEMS, INC. reassignment CONEXANT SYSTEMS, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ZARLINK SEMICONDUCTOR V.N. INC., ZARLINK SEMICONDUCTOR, INC.
Assigned to BANK OF NEW YORK TRUST COMPANY, N.A. reassignment BANK OF NEW YORK TRUST COMPANY, N.A. SECURITY AGREEMENT Assignors: CONEXANT SYSTEMS, INC.
Publication of US20090031044A1 publication Critical patent/US20090031044A1/en
Assigned to CONEXANT SYSTEMS, INC. reassignment CONEXANT SYSTEMS, INC. RELEASE BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.
Assigned to IKANOS COMMUNICATIONS, INC. reassignment IKANOS COMMUNICATIONS, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BROOKTREE BROADBAND HOLDING INC., CONEXANT SYSTEMS, INC., CONEXANT, INC.
Abandoned legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L49/00Packet switching elements
    • H04L49/35Switches specially adapted for specific applications
    • H04L49/351Switches specially adapted for specific applications for local area network [LAN], e.g. Ethernet switches
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00Routing or path finding of packets in data switching networks
    • H04L45/74Address processing for routing
    • H04L45/745Address table lookup; Address filtering
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L49/00Packet switching elements
    • H04L49/30Peripheral units, e.g. input or output ports
    • H04L49/3009Header conversion, routing tables or routing tags

Definitions

  • the present invention relates to computer network technology. More particularly, the present invention relates to searching and forwarding of frames and computer addresses in a computer network. Description Of Related Art
  • a computer network generally comprises a set of conjoined computer devices that are communicatively linked so as to share resources such as storage devices, peripherals, applications, output devices, etc.
  • the computing devices in a local area network (LAN) are typically connected to each other directly by cable connections.
  • LAN local area network
  • a hub typically has a plurality of ports that are each communicatively linked to one or more devices, such as a node, a switch, or a repeater.
  • node refers to any device that can communicated with other computers in a network.
  • the hub receives an incoming signal from a source node through one port and sends the incoming signal out to a destination node through one or more other ports.
  • a repeater is a very simple form of a hub. Repeaters extend the size of a network by joining multiple segments into a larger segment. Repeaters increase a network signal's strength so the signal can be transmitted and received over a greater distance without a loss in quality. For example, the signal may have become degraded due to the distance traveled from the source to the repeater over the cable.
  • the repeater regenerates the weak signal internally and forwards the signal out through all ports. This means that a repeater does not process data at all, but rather merely receives incoming signals and reconditions them for immediate transmission on all ports (except the originating port). That is, the repeater does not perform any analysis as to the destination address of the signal, but rather blindly sends the signal out through all ports.
  • a repeater can significantly increase the traffic level of a network because the repeater outputs all incoming signals through every port. This may not present a problem in networks where communication traffic is relatively low. However, in networks where traffic volume is relatively high, small increases in communication traffic may significantly degrade the performance of the network.
  • Switches and bridges are more complex types of hubs that overcome the aforementioned drawbacks associated with repeaters. Unlike repeaters, switches and bridges include frame forwarding logic and perform basic signal filtering functions before transmitting an incoming signal. Whereas repeaters forward all signals through every port, switches and bridges only forward signals that are necessary and only forward the signals to the appropriate port based upon the destination address of the signal.
  • signals are transmitted through the network as frames of data that travel from the source node to the destination node.
  • a frame is generally comprised of several fields of information, including two fields that denote the destination Media Access Control (MAC) address and the source MAC address for the frame.
  • the source MAC address specifies the source node of the frame and the destination MAC address specifies the destination node of the frame.
  • Each node in the network is identified by a unique MAC address, which comprises a 48 bit (6 byte) string. Six bytes of device ID allows for approximately 32 trillion (2 48 ) possible unique MAC addresses;
  • the switch or bridge When a switch or a bridge receives an incoming frame, the switch or bridge examines the frame's destination address.
  • the switch maintains in internal memory a database of past frames. Through use of the database, referred to herein as an address table, the switch can keep track of which MAC addresses correspond to which ports on the switch.
  • the switch Upon receipt of a frame, the switch references the database and determines the port that is associated with the particular MAC address. The switch then forwards the frame to the correct port. Essentially, the switch checks its internal memory of past frames and determines whether to forward the frame to another port i or to filter out the frame.
  • the speed at which a switch can forward a frame to the correct port is dependent on several factors, including the amount of time that it takes for the frame to search its address table, find the frame's destination address and output the frame through the correct port(s).
  • an address table would contain enough data space to store each and every possible 6 byte MAC address.
  • the address table could contain an array of entries comprised of a complete listing of every single possible address and the port corresponding to each address.
  • the invention contemplates an apparatus and method for storing and searching computer node addresses in a computer network system.
  • the system is described in the exemplary context of storing and searching MAC addresses in an Ethernet system.
  • the system comprises a frame forwarding device such as a switch.
  • the switch includes two MAC address tables including a primary MAC address table and secondary MAC address table both for storing and searching MAC addresses.
  • the primary MAC address table is preferably stored in a memory that is external to the switch and the secondary MAC address table is preferably stored in a memory that is internal to the switch.
  • the primary table is preferably sensitive in data entry size according to the bus width of the external memory and may have a slower access speed and larger size than the secondary table.
  • a search module is configured to perform on a bandwidth that is optimized to the memory in which the secondary address table is stored.
  • the primary address table stores records that contain MAC addresses.
  • the records are contained in storage locations that are referenced using a compressed or hashed value of the MAC address as a search index.
  • each record in the primary address table may be linked to a hash family of chain of records in the secondary table.
  • Each hash family chain of records in the secondary address table contains MAC addresses that belong to the same hash family, or MAC addresses that compress to the same value.
  • a method of searching for a computer address in an address table where the computer address having a bit size n.
  • the bit size n computer address is partitioned into an upper set of n-m bits and a lower set of m bits, with m being a value less than bit size n.
  • a search index is then generated by compressing the upper set of n-m bits to obtain a compressed value of the computer address, resulting in the search index having a number of bits equal to the number of bits of the lower set of m bits.
  • a primary address record corresponding to the computer address is accessed via a primary address table.
  • the primary address record is accessed by using the search index to locate the primary address record, wherein the primary address record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary address record in a secondary address table.
  • the search index is then compared to the primary address record by selecting the m low order bits of the combination of the search index and the lower set of m bits resulting in a first value.
  • the compressed value of the address contained in the primary address record is decompressed to obtain a second value.
  • the first and second values are compared and if the first value does not equal the second value, then the initial secondary address record is accessed using the link.
  • the initial secondary address record includes a respective address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • a storage and search unit for computer addresses with each having a fixed bit size n.
  • the unit includes a primary address table stored within a first memory of a first bus width, the primary address table configured to store a plurality of primary address records, each primary address record including a respective address entry of a first bit size less than the fixed bit size n, a port number associated with the compressed address entry and a first link that links each primary address record to a corresponding chain of secondary address records in a second address table.
  • a secondary address table stored within a second memory separate from the first memory, the second address table configured to store a plurality of secondary address records, each secondary address record including a respective address entry of the first bit size less than the fixed bit size n, a port number associated with the computer address, and a link that links each secondary address record to a corresponding secondary address record in the second address table to thereby form one or more linked chains of secondary address records, wherein each chain of secondary address records contains full address entries of the same hash family.
  • the unit further comprises a software search module configured to store and access the primary address records and secondary address records, wherein the software module stores each primary address record in a location defined by the value of the respective compressed address entry.
  • a computer readable software stored within a frame forwarding device of a computer network.
  • the computer readable software code includes a set of instructions, which cause the device to search for a computer address of bit size n in an address table.
  • the software partitions the bit size n computer address into an upper set of n-m bits and a lower set of m bits, with m being less than n.
  • the instructions then generate a search index by compressing the upper set of n-m bits to obtain a compressed value of the computer address.
  • the search index having the same number of bits as the lower set of bits.
  • the software accesses a primary address record corresponding to the computer address in a primary address table by using the search index.
  • the primary address record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary address record in a secondary address table.
  • the software then instructs the comparison of the search index to the primary address record.
  • the instructions further include selecting the m low order bits of the combination of the search index and the lower set of m bits to determine a first value.
  • the compressed value of the address contained in the primary address record is then decompressed to obtain a second value.
  • the instructions compare the first value and the second value and if the first value does not equal the second value, the instructions provide for an initial secondary address record to access via the link.
  • the initial secondary address record includes a respective address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • a method of searching for a computer address in an address table where the computer address having a bit size n.
  • the bit size n computer address is partitioned into an upper set of n-m bits and a lower set of m bits, with m being a value less than bit size n.
  • a search index is then generated by compressing the upper set of n-m bits to obtain a compressed value of the computer address, resulting in the search index having a number of bits equal to the number of bits of the lower set of m bits.
  • An address record corresponding to the computer address is accessed via an address table.
  • the address record is accessed by using the search index to locate the address record, wherein the address record includes the computer address, and a port number associated with the computer address.
  • the search index is then compared to the address record by selecting the m low order bits of the combination of the search index and the lower set of m bits resulting in a first value.
  • the compressed value of the address contained in the address record is decompressed to obtain a second value.
  • the first and second values are compared to determine if a match has occurred.
  • a search index having a first number of bits less than the bit size n, is generated by compressing the computer address to obtain a compressed value of the address.
  • At least two primary address records, located using the search index, are then accessed corresponding to an equal number of computer addresses stored in a primary address table.
  • the primary address records include the computer addresses, a port number associated with each of the computer addresses, and a link that specifies the location of an initial secondary address record in a secondary address table.
  • the search index and the primary address records are then simultaneously compared by decompressing the search index to obtain a first value, decompressing the compressed values of the addresses contained in each of the primary address records, and comparing the first value to the values of the addresses of the primary address records. If the first value does not equal any of the values of the addresses of the primary address records, then the initial secondary address record is accessed using the link.
  • the initial secondary address record includes a computer address, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • a method for forwarding a frame to a computer address using classification based upon multiple fields in a header has a first field of bit size n-m and a second field having a bit size m, with m being less than n.
  • the first field of bit size n-m and the second field of bit size m are concatenated into a bit size n.
  • a search index having a number of bits equal to the number bits of the second field, is then generated by compressing the concatenated bit size n to obtain a compressed value of the concatenated fields.
  • a primary record corresponding to the computer address in a primary table is accessed, the primary record being accessed by using the search index to locate the primary record.
  • the primary record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary record in a secondary table.
  • the search index is compared to the primary record by first selecting the concatenated fields of bit size m of the search index and the second field of bit size m, resulting in a first value.
  • the compressed value of the address contained in the primary record is then decompressed to obtain a second value.
  • the first value is compared to the second value, and if the first value does not equal the second value, then accessing the initial secondary record using the link, wherein the initial secondary record includes a respective computer address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary record of the same hash family.
  • FIG. 1 is a schematic illustration of a network system.
  • FIG. 2 is a schematic illustration of a switch component of the network system.
  • FIG. 3 is an illustration of a preferred embodiment of a primary address table and a secondary address table.
  • FIG. 3 A is an illustration of an embodiment of a compression of an address utilized by the method of the present invention.
  • FIG. 3B is an illustration of an alternate embodiment of a compression of an address utilized by the method of the present invention.
  • FIG. 4 is an illustration of several hash family chains of address storage records.
  • FIG. 5 A is a flow chart that describes a process of allocating resources for the secondary address table.
  • FIG. 5B shows a first example of a secondary address table that has been allocated in accordance with the process of FIG. 5 A.
  • FIG. 5C shows a second example of a secondary address table that has been allocated in accordance with the process of FIG. 5 A.
  • FIG. 6 is a flow chart that describes frame forwarding mechanisms of the switch component.
  • FIGS. 7A-7D are flow charts that describe a method of searching and populating primary and secondary address tables.
  • FIG. 1 schematically illustrates a local area network (LAN) 100 that includes a plurality of computer nodes.
  • the computer nodes are referred to collectively using the reference numeral 105 and individually using the reference numeral 105 followed by a letter suffix. Additional devices, such as printers, scanner, copiers, and other devices, such as multifunction peripherals (MFPs) and fax devices, may also be coupled to the LAN 100 .
  • the LAN 100 is described herein in the context of an Ethernet network topology, although the principles described herein could also be applied to other types of network topologies in accordance with the disclosure herein.
  • the LAN 100 could also include one or more signal forwarding devices such as a router, repeater, etc.
  • Each of the computer nodes 105 is centrally connected to a switch 115 .
  • the switch 115 includes a plurality of ports 120 a - 120 d (collectively, ports 120 ).
  • the switch 115 is configured to receive one or more incoming frames through a first port 120 and thereafter transmit each frame through one or more other ports 120 so that the frame reaches its intended destination.
  • the switch 115 includes a search module that examines the destination MAC address of the frame and forwards the frame to the correct port 120 , as described in more detail below.
  • the search module is preferably implemented using software instructions that are stored within memory of the switch 115 . It will be appreciated that the searching and forwarding functions described herein are not limited to a switch and could be implemented in any network device that implements address searching and frame forwarding logic.
  • FIG. 2 schematically illustrates the switch 115 in which an embodiment of the invention may be implemented.
  • the switch 115 includes a representative plurality of ports 120 that are communicatively coupled to the one or more computer nodes 105 ( FIG. 1 ). Although the switch 115 is shown as having only four ports, it will be appreciated that the number of ports 120 could vary.
  • the switch 115 includes a memory that stores a search module 210 that is configured to examine and process the source and/or destination MAC address of incoming frames and to determine which port(s) 120 the frame should be forwarded to for the frames to reach the intended destination.
  • the switch 115 stores and maintains in memory a primary MAC address table 220 a that is used to store MAC addresses and associated port identifiers.
  • the switch 115 also stores and maintains in memory a secondary MAC address table 220 b that is linked to and used in conjunction with the primary MAC address table 220 a .
  • the secondary MAC address table 220 b is also used to store MAC addresses and associated port identifiers.
  • the primary and secondary MAC address tables 220 preferably each have a predetermined format, as described more fully below.
  • the address tables 220 are described herein in the context of storing a MAC address, although it will be appreciated that the tables 220 could be used to store other embodiments of node addresses for a network system.
  • the primary MAC address table 220 a comprises a data structure that includes a plurality of primary records 305 that are arranged in an array format such that one primary record 305 a in the table 220 a is followed by a successive record 305 b in the table and so on.
  • Each primary record 305 includes an address field for storing a MAC address (either a compressed or a full version), a port field for storing the port identifier with which the MAC address is associated, and a link field for storing a hash family link index that specifies the location of a corresponding secondary record 330 in the secondary MAC address table 220 b or to a null link, as described below.
  • Each primary record 305 could also include additional information related to the MAC address.
  • the primary MAC address table 220 a is preferably indexed as a function of the values of the MAC addresses that are stored within the primary MAC address table 220 a .
  • a hashing function is performed on all stored MAC addresses and the hashed value of each MAC address is used as an index for locating the particular primary record 305 in which that MAC address is stored.
  • the contents of each primary record 305 may be accessed using a primary index that points to the memory location of the particular primary record 305 .
  • the value of the primary index is equal to the hashed value of the MAC address that is stored within that primary record 305 .
  • MAC addresses that map to the same value are referred to herein as belonging to the same “hash family.”
  • the addresses 100 and 200 belong to the same hash family. This may result in collisions during indexing of the primary MAC address table 220 a , as two different MAC addresses would have the same primary index.
  • the likelihood of collisions occurring is a function of the hash algorithm as well as a function of the amount of compression of the MAC address that occurs during the hash.
  • the MAC addresses are hashed to a bit width of 16 bits, although the compression width can be any width less than the original width. For a compression to 16 bits, there are 65,536 possible hash families.
  • FIG. 3 A depicts a particular embodiment of the determination of the primary index using hashing.
  • a full computer address 350 has a size of n bits. Compressing the MAC address 350 results in an index a 352 of a size of m bits, with m being of a substantially smaller size than n. The index a then links to a corresponding record 305 in the primary address table 220 a .
  • FIG. 3B a hybrid hashing method for use in the present invention.
  • a MAC address 354 is partitioned into two smaller components, an upper n-m bit component 356 and a lower m bit component 358 .
  • the n-m bit component 356 is then compressed to provide an index a 360 of m bit size.
  • the search index a 360 is compared to the primary record 305 by selecting the low order bits of size m 358 combined with the search index a 360 .
  • the value of the address in the primary record 305 is then decompressed and the two values are compared, as discussed in further detail below.
  • Each primary record 305 can be linked to a corresponding secondary record 330 in the secondary MAC address table 220 b . If linked, a primary record 305 is preferably linked to a chain of one or more secondary records 330 that store MAC addresses of the same hash family as is stored in the primary record 305 . Thus, MAC addresses of the same hash family are stored within the same hash family chain of linked primary and secondary records 305 , 330 .
  • the term “hash family chain” refers to a linked chain of at least one primary record and possibly one or more secondary records, wherein the linked records all store addresses of the same hash family.
  • the memory location of the first secondary record 330 in such a hash family chain is specified in the hash family link field of the primary record 305 in the chain. If the MAC address in a primary record 305 belongs to a hash family chain comprised of only one record, the primary record 305 is preferably linked to a null pointer.
  • the primary MAC address table 220 a is sized to store at least as many primary records 305 as there are hash families. In one embodiment, the primary MAC address table 220 a is configured to store at least 64 k (65,536) primary records 305 .
  • the primary MAC address table is preferably stored in a memory that is external to the switch 115 . The size or width of each primary record 305 is preferably selected to be less than or equal to the bus width of the external memory.
  • FIG. 3 also shows a schematic illustration of a preferred format for the Primary MAC address table 220 a and secondary MAC address table 220 b .
  • the secondary MAC address table 220 b comprises a data structure that includes a plurality of secondary records 330 arranged in an array format.
  • Each secondary record 330 includes an address field for storing a MAC address, a port field for storing the port identifier with which the MAC address is associated, and a hash family link field that contains a hash family link that specifies the location of another secondary record 330 that stores a MAC address of the same hash family.
  • the hash family link field contains a null pointer.
  • the last secondary record 330 in each hash family chain is preferably linked to a null pointer to indicate the end of the hash family chain.
  • the secondary MAC address table 220 b is preferably located in memory that is internal to the switch 115 .
  • the secondary MAC address table 220 b is preferably also smaller in size than the primary MAC address table 220 a .
  • the secondary MAC address table 220 b is sized to store 2,048 secondary records 330 .
  • content addressable memory is used for the secondary address table 220 b .
  • Content addressable memory includes comparison logic with each bit stored.
  • content addressable memory may be used for the secondary address table 220 b , housing only those records 330 a - g that cannot fit into the primary address table 220 a because those records 330 a - g collide with other records that has to the same row in the primary address table 220 a .
  • present application may be suitably adapted to high traffic operations, where the high volume of transiting packets warrants the exclusion of a secondary address table, thereby resulting in faster throughput, with a higher collision rate.
  • FIG. 3 shows an exemplary embodiment of the primary MAC address table 220 a and the secondary MAC address table 220 b both being at least partially populated with data.
  • the primary MAC address table 220 a is populated with MAC addresses 100 , 200 , 300 , 400 in primary records 305 a - 305 d , respectively.
  • the secondary MAC address table 220 b is populated with MAC addresses A, B, C, D, E, F, and G in secondary records 330 a - 330 g , respectively.
  • the index values of the secondary records 330 a - 330 g are 1-7, respectively.
  • MAC addresses 100 , A, B, and C are of the same hash family; MAC addresses 200 , D, and E are of the same hash family; MAC address 300 , F and G are of the same hash family; and MAC address 400 is in its own hash family. Therefore, there are four separate hash family chains contained in the exemplary tables 220 a and 220 b , as shown in FIG. 4 .
  • a first hash family chain 403 is comprised of primary record 305 a and secondary records 330 a , 330 b , and 330 c all linked in series.
  • the hash family link field in primary record 305 a contains the index (1) of secondary record 330 a , which is the next record in the chain.
  • the hash family link field of secondary record 330 a contains the index (2) of secondary record 330 b .
  • the hash family link field of the secondary record 330 b contains the index (3) of secondary record 330 c , the next (and last) record in the hash family chain.
  • secondary record 330 c contains a null value in its hash family link field, indicating that secondary record 330 c is the last record in the hash family chain 403 .
  • a second hash family chain 407 is comprised of primary record 305 b and secondary records 330 d and 330 e , which are all linked in series.
  • the hash family link fields of the primary records 305 b and secondary records 330 d and 330 e each contain the index to the next record in the hash family chain 407 .
  • Secondary record 330 e as the last record in the chain, is linked to a null pointer.
  • primary record 305 c and secondary records 330 f and 330 g collectively form yet a third hash family chain 409 .
  • Primary record 305 d is the sole link in a fourth hash family chain 411 and is linked to a null pointer, as indicated by the null value in its hash family link field ( FIG. 3 ).
  • FIG. 5 A is a flow chart that describes a process of allocating resources for the secondary MAC address table 220 b .
  • an array of unpopulated secondary records is formed in internal memory of the switch 115 .
  • at least one of the records in the array is reserved as a null record.
  • 0 is used as NULL pointer.
  • the secondary records are all linked in series to thereby form a resource allocation chain comprised of all of the secondary records linked in a single chain.
  • the first record in the resource allocation chain is referred to as the start record and the last record in the chain (not including the null record) is referred to as the end record.
  • the switch 115 memorizes the memory address for the start record and the end record of the resource allocation chain. It will be appreciated that addresses of the start record and the end record in the resource allocation chain may change as the secondary MAC address table 220 b is populated and maintained. The switch 115 preferably keeps track of such address changes so that the addresses for the start and end records of the resource allocation chain are constantly updated.
  • step 511 the end record of the resource allocation chain is linked to the null record. The resource allocation process then ends.
  • FIG. 5B shows an exemplary secondary address table 220 b having six secondary records designated with indices of 0 through 5 .
  • the secondary record with index 0 is reserved as the null record.
  • the start record is the secondary record with index 1 and the end record is the secondary record with index 5 so that the resource allocation chain is comprised of secondary records 1 , 2 , 3 , 4 , and 5 , linked in that order.
  • the end record is linked to the null record.
  • FIG. 5C shows the resource allocation chain being comprised of secondary records 1 , 4 , 5 , 2 , and 3 , lined in that order.
  • record 1 is the start record and record 3 is the end record.
  • FIG. 6 is a flow chart that generally describes the frame forwarding mechanism for the switch 115 .
  • the switch 115 receives an incoming frame through a particular port 120 .
  • the switch 115 next examines the source address portion of the frame and obtains the MAC address of the node from which the frame originated (step 610 ).
  • step 615 the switch 115 invokes the search module 210 to search the MAC address tables 220 and determine whether the source address is present in the tables (step 620 ).
  • the source address is first hashed to obtain the primary search index that is used to access a primary record 305 in the primary MAC address table 220 a .
  • the searching process is described in more detail with respect to FIGS. 7A-7D .
  • the tables 220 are populated with information related to the source MAC address (step 625 ).
  • the information preferably includes: (1) the source address of the frame; (2) the port number corresponding to the source address; and (3) any other relevant information, such as the age of the source address.
  • node 105 a FIG. 1
  • the switch 115 would populate the MAC address tables 220 with the MAC address 100 and the port identifier for port 120 a . In this manner, the switch “learns” the MAC addresses and corresponding ports.
  • the reason that a particular source address would not be present in the tables 220 could vary.
  • the switch 115 could be new on the network, the sending device could be new on the network, or the sending device could have been quiet recently (i.e., the sending device has not recently sent a frame).
  • the switch 15 may use the age entry of the MAC address table as a means of periodically maintaining the size of the MAC address table. For example, if the age of the MAC address entry has exceeded a predetermined time limit, then the switch could remove the entry from the MAC address table. This would conserve memory and also improve access speed because fewer entries need to be examined.
  • the switch 115 then obtains the destination MAC address from the frame (step 630 ). The switch 115 then invokes the search module 210 to search the MAC address tables 220 (step 635 ), in accordance with the method described below with respect to FIG. 5 . Depending upon whether the destination MAC address is present in the MAC address tables 220 , the frame is then forwarded through the appropriate port(s) 120 or discarded in a conventional manner.
  • the switch 115 forwards the frame to all ports to ensure that the frame eventually gets to its recipient. If the destination MAC address is found in the MAC address tables 120 , the switch 115 obtains the details of the destination MAC address from the tables 120 including which port that the destination MAC address is associated with. The switch 115 then sends the frame out through the appropriate port 120 .
  • the switch 115 preferably filters the frame (i.e., discards the frame). The frame is discarded because the source node and the destination node are both located on the same shared segment of the LAN. Thus, the frame would have already been transmitted to the destination address without having to travel through the switch 115 .
  • FIGS. 7A-7C show flow charts that describe a process by which search module searches the MAC address tables 220 and also learns MAC address information using the MAC address tables 220 .
  • the switch 115 preferably includes hardware and/or software that are configured to implement the described process.
  • the search module 210 obtains a MAC address (the “incoming address”) from a frame.
  • a MAC address the “incoming address”
  • an exemplary frame includes several fields, including a field for the destination address and the source address of the frame.
  • the search module 210 obtains the MAC address in a well-known manner.
  • the search module 210 hashes the incoming MAC address to generate the primary index.
  • the search module preferably hashes the incoming MAC address to a size smaller than the 48 bit size of a full MAC address.
  • the incoming MAC address may be hashed using a hashing function that uses the value of the incoming MAC address to output a compressed or hashed value.
  • the search module 210 uses the primary index to locate and retrieve a primary record 305 in the primary MAC address table 220 a .
  • the hashed value of the incoming MAC address is used to locate a primary record 305 in the primary MAC address table 220 a .
  • the located primary record will be referred to as primary record 305 a.
  • the search module 210 then examines the primary record 305 a and determines whether the primary record 305 a is empty or populated with data (step 720 ). If the primary record 305 a is empty, it means that a hash family chain does not yet exist for the incoming MAC address. If this is the case, the search module 210 then proceeds to process B ( FIG. 5B ), where the search module establishes the first link in a new hash family chain by populating the primary record 305 a with information associated with the incoming MAC address.
  • the search module 210 begins populating the primary record 305 a with the MAC address data.
  • the search module 210 populates the MAC address field ( FIG. 3 ) of the primary record 305 a with the incoming MAC address.
  • the search module populates the port field ( FIG. 3 ) with an identifier for the port that is associated with the incoming MAC address.
  • the search module 210 sets the link field ( FIG. 3 ) in the primary record 305 a to a null value, thereby indicating that the primary record 305 a is currently the only record in this particular hash family chain.
  • the link field could have a default value of null and remain so until changed.
  • the search module has established a new hash family chain with the primary record 305 a being the first (and only) link in the chain. The process is the complete.
  • the search module 210 may discover that the primary record 305 a is already populated with data. This means that a hash family chain already exists for the incoming MAC address, although the number of links in the chain is unknown. If this is the case, the search module 210 proceeds to process C, which is described in FIG. 7C .
  • the illustrated flow chart describes the performance of the search module 210 where the primary record 305 a is already populated with data.
  • the search module compares the incoming MAC address to the MAC address that is stored in the record (the “retrieved address”) and determines whether the addresses are the same. If the incoming address is indeed the same as the retrieved address, then a match has been found. The search module 210 then obtains the data from primary record 305 a (step 747 ) and the process is complete.
  • step 749 the search module examines the link field of the primary record 305 a and determines whether the link field has a null value.
  • the link field indeed contains a null value, then it means that the primary record 305 a is currently the only record in the hash family chain for that record and the search module 210 should proceed to establish a new record in the hash family chain.
  • the new record in the chain will store the incoming MAC address.
  • step 751 the search module 210 uses the resource allocation chain (discussed above with respect to FIGS. 5A-5C ) of the secondary address table 220 b to retrieve a secondary record for storing the incoming MAC address and appending to the hash family chain.
  • the secondary record that is retrieved is referred to herein as a “retrieved secondary record.”
  • the search module 210 preferably uses the start record in the resource allocation chain as the retrieved secondary record.
  • the search module 210 populates the address field and the port field of the retrieved secondary record with the appropriate information related to the incoming MAC address.
  • the search module 210 also populates the hash family link field with a null value thereby indicating that the retrieved secondary record is now the last link in the hash family chain.
  • step 755 the search module sets the hash family link field of the primary record 305 a to the point to the location of the retrieved secondary record. In this manner, the primary record 305 a and the retrieved secondary record are linked as two records in the same hash family chain.
  • step 757 the search module updates the resource allocation chain to reflect that the retrieved secondary record has been populated with new data. Additionally, the next consecutive secondary record ( FIG. 5B , 2 ) in the resource allocation chain after the retrieved secondary record is designated as the new start secondary record. The process is then complete.
  • the search module 210 may discover that the primary record 305 a does not contain a null value for its hash family link but rather contains a pointer to a secondary record. This means that the primary record 305 a is already linked to one or more secondary records in a hash family chain. If so, the search module 210 then proceeds to process D, which is described with respect to FIG. 7D .
  • the search module retrieves a secondary record (the “retrieved secondary record”) using the hash family link that is contained in the primary record 305 a .
  • the retrieved secondary record is the next record in the hash family chain for the incoming MAC address.
  • the search module 210 then retrieves the MAC address contained in the retrieved secondary record.
  • the search module determines whether the retrieved address matches the incoming address. If the incoming address is indeed the same as the retrieved address, then a match has been found.
  • the search module 210 obtains the data from the retrieved secondary record (step 769 ) and the process is complete.
  • step 771 the search module examines the hash family link field of the retrieved secondary record and determines whether the link field has a null value. If the link field does not contains a null value, then it means that additional secondary records are linked to the current hash family chain. If this is the case, the search module uses the hash family link that is specified in the hash family link field to retrieve the next secondary record in the hash family chain (step 765 ). The search module loops through steps 765 , 767 , and 771 until either a match is found in step 767 or a null link is found in step 771 .
  • the search module 210 should proceed to append yet another record to the end of the hash family chain for storing the incoming MAC address.
  • step 773 the search module 210 uses the resource allocation chain of the secondary address table 220 b to retrieve a new secondary record for appending to the hash family chain.
  • the search module 210 preferably uses the start record in the resource allocation chain as the new secondary record.
  • the search module 210 populates the address field and the port field of the new secondary record with the appropriate information related to the incoming MAC address.
  • the search module 210 also populates the hash family link field with a null value thereby indicating that the retrieved secondary record is now the last link in the hash family chain.
  • step 777 the search module 210 sets the hash family link field of the previous secondary record in the hash family chain (the one with null pointer) to point to the location of the new secondary record that now stores the incoming MAC address. In this manner, the hash family chain has been extended by an additional record.
  • the search module 210 updates the resource allocation chain to reflect that the retrieved secondary record has been populated with new data. Additionally, the next consecutive secondary record in the resource allocation chain after the retrieved secondary record is designated as the new start secondary record. The process is then complete.
  • the present invention may be applied to multi-field i classifications by concatenating both a 48-bit MAC address and a 12-bit VLAN identifier. A combined 60-bit value may be used to generate a search index. It will be appreciated by those skilled in the art that the use of two fields is exemplary only. Additional fields contained in a data packet header may also be used, thereby further reducing the likelihood of collision. The skilled artisan will further appreciate that concatenation may be accomplished prior to the combination of multiple fields. Thus, each field may be hashed individually, then subsequently concatenated into a larger, albeit compressed value. The concatenated result may then be further hashed, thereby reducing the size of the search index and further reducing the likelihood of collision.

Abstract

Disclosed is an apparatus and method for storing and searching computer node addresses in a computer network system. In one embodiment, the apparatus comprises a frame forwarding device such as a switch. The switch includes two MAC address tables including a primary MAC address table and secondary MAC address table both for storing and searching MAC addresses. The primary table stores records that contain compressed values of MAC addresses. The records are contained in storage locations that are referenced using the compressed value of the MAC address as a search index. In order to account for searching collisions that may result from different MAC addresses compressing to the same value, each record in the primary address table is linked to a chain of records in the secondary table. The records in the secondary table store the full value of the MAC address. Each chain of records in the secondary address table contains MAC addresses the present invention.

Description

    CROSS-REFERENCE TO RELATED APPLICATION
  • This application is a continuation of U.S. application Ser. No. 10/750,445 filed Dec. 31, 2003, which is a Continuation-In-Part of U.S. Ser. No. 09/643,567, filed Aug. 22, 2000 and issued as U.S. Pat. No. 6,697,873 on Feb. 24, 2004, all of which are incorporated herein by reference as if set forth in their entireties.
  • BACKGROUND OF THE INVENTION Field of Invention
  • The present invention relates to computer network technology. More particularly, the present invention relates to searching and forwarding of frames and computer addresses in a computer network. Description Of Related Art
  • A computer network generally comprises a set of conjoined computer devices that are communicatively linked so as to share resources such as storage devices, peripherals, applications, output devices, etc. The computing devices in a local area network (LAN) are typically connected to each other directly by cable connections. For organizational reasons, several devices in a network may be connected at a central connection point referred to herein as a hub. A hub typically has a plurality of ports that are each communicatively linked to one or more devices, such as a node, a switch, or a repeater. As used herein, the term “node” refers to any device that can communicated with other computers in a network. The hub receives an incoming signal from a source node through one port and sends the incoming signal out to a destination node through one or more other ports.
  • A repeater is a very simple form of a hub. Repeaters extend the size of a network by joining multiple segments into a larger segment. Repeaters increase a network signal's strength so the signal can be transmitted and received over a greater distance without a loss in quality. For example, the signal may have become degraded due to the distance traveled from the source to the repeater over the cable. The repeater regenerates the weak signal internally and forwards the signal out through all ports. This means that a repeater does not process data at all, but rather merely receives incoming signals and reconditions them for immediate transmission on all ports (except the originating port). That is, the repeater does not perform any analysis as to the destination address of the signal, but rather blindly sends the signal out through all ports.
  • A repeater can significantly increase the traffic level of a network because the repeater outputs all incoming signals through every port. This may not present a problem in networks where communication traffic is relatively low. However, in networks where traffic volume is relatively high, small increases in communication traffic may significantly degrade the performance of the network.
  • Switches and bridges are more complex types of hubs that overcome the aforementioned drawbacks associated with repeaters. Unlike repeaters, switches and bridges include frame forwarding logic and perform basic signal filtering functions before transmitting an incoming signal. Whereas repeaters forward all signals through every port, switches and bridges only forward signals that are necessary and only forward the signals to the appropriate port based upon the destination address of the signal.
  • In relation to the Ethernet network standard, signals are transmitted through the network as frames of data that travel from the source node to the destination node. A frame is generally comprised of several fields of information, including two fields that denote the destination Media Access Control (MAC) address and the source MAC address for the frame. The source MAC address specifies the source node of the frame and the destination MAC address specifies the destination node of the frame. Each node in the network is identified by a unique MAC address, which comprises a 48 bit (6 byte) string. Six bytes of device ID allows for approximately 32 trillion (248) possible unique MAC addresses;
  • When a switch or a bridge receives an incoming frame, the switch or bridge examines the frame's destination address. The switch maintains in internal memory a database of past frames. Through use of the database, referred to herein as an address table, the switch can keep track of which MAC addresses correspond to which ports on the switch. Upon receipt of a frame, the switch references the database and determines the port that is associated with the particular MAC address. The switch then forwards the frame to the correct port. Essentially, the switch checks its internal memory of past frames and determines whether to forward the frame to another port i or to filter out the frame.
  • The speed at which a switch can forward a frame to the correct port is dependent on several factors, including the amount of time that it takes for the frame to search its address table, find the frame's destination address and output the frame through the correct port(s). Ideally, an address table would contain enough data space to store each and every possible 6 byte MAC address. In such a case, the address table could contain an array of entries comprised of a complete listing of every single possible address and the port corresponding to each address. Upon receipt of a MAC address, the switch could then quickly search through the table and identify the appropriate port to which the MAC address should be forwarded.
  • However, as mentioned, there are approximately 32 trillion (248) possible MAC addresses that would have to be stored in such a table. In the real world, it would not be practical from a cost standpoint to maintain sufficient memory to store a table that contains each and every possible six byte MAC address. One way of reducing the amount of memory required for an address table would be to store a compressed or hashed version of the address in the table. However, this could result in collisions during searching as one or more different addresses could map to the same hash value.
  • Consequently, there is a need for a fast and efficient method of maintaining computer address forwarding tables.
  • SUMMARY OF THE INVENTION
  • In view of the aforementioned needs, the invention contemplates an apparatus and method for storing and searching computer node addresses in a computer network system. The system is described in the exemplary context of storing and searching MAC addresses in an Ethernet system. The system comprises a frame forwarding device such as a switch. The switch includes two MAC address tables including a primary MAC address table and secondary MAC address table both for storing and searching MAC addresses. The primary MAC address table is preferably stored in a memory that is external to the switch and the secondary MAC address table is preferably stored in a memory that is internal to the switch. The primary table is preferably sensitive in data entry size according to the bus width of the external memory and may have a slower access speed and larger size than the secondary table. In order to increase the searching speed of the secondary address table, a search module is configured to perform on a bandwidth that is optimized to the memory in which the secondary address table is stored.
  • In one aspect of the invention, the primary address table stores records that contain MAC addresses. The records are contained in storage locations that are referenced using a compressed or hashed value of the MAC address as a search index. In order to account for searching collisions that may result from different MAC addresses hashing to the same value, each record in the primary address table may be linked to a hash family of chain of records in the secondary table. Each hash family chain of records in the secondary address table contains MAC addresses that belong to the same hash family, or MAC addresses that compress to the same value.
  • In accordance with the present invention, there is provided a method of searching for a computer address in an address table where the computer address having a bit size n. The bit size n computer address is partitioned into an upper set of n-m bits and a lower set of m bits, with m being a value less than bit size n. A search index is then generated by compressing the upper set of n-m bits to obtain a compressed value of the computer address, resulting in the search index having a number of bits equal to the number of bits of the lower set of m bits. A primary address record corresponding to the computer address is accessed via a primary address table. The primary address record is accessed by using the search index to locate the primary address record, wherein the primary address record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary address record in a secondary address table. The search index is then compared to the primary address record by selecting the m low order bits of the combination of the search index and the lower set of m bits resulting in a first value. The compressed value of the address contained in the primary address record is decompressed to obtain a second value. The first and second values are compared and if the first value does not equal the second value, then the initial secondary address record is accessed using the link. The initial secondary address record includes a respective address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • Further in accordance with the present invention, there is provided a storage and search unit for computer addresses with each having a fixed bit size n. The unit includes a primary address table stored within a first memory of a first bus width, the primary address table configured to store a plurality of primary address records, each primary address record including a respective address entry of a first bit size less than the fixed bit size n, a port number associated with the compressed address entry and a first link that links each primary address record to a corresponding chain of secondary address records in a second address table. Also included in the unit is a secondary address table stored within a second memory separate from the first memory, the second address table configured to store a plurality of secondary address records, each secondary address record including a respective address entry of the first bit size less than the fixed bit size n, a port number associated with the computer address, and a link that links each secondary address record to a corresponding secondary address record in the second address table to thereby form one or more linked chains of secondary address records, wherein each chain of secondary address records contains full address entries of the same hash family. The unit further comprises a software search module configured to store and access the primary address records and secondary address records, wherein the software module stores each primary address record in a location defined by the value of the respective compressed address entry.
  • Still in accordance with the present invention, there is provided a computer readable software stored within a frame forwarding device of a computer network. The computer readable software code includes a set of instructions, which cause the device to search for a computer address of bit size n in an address table. The software then partitions the bit size n computer address into an upper set of n-m bits and a lower set of m bits, with m being less than n. The instructions then generate a search index by compressing the upper set of n-m bits to obtain a compressed value of the computer address. The search index having the same number of bits as the lower set of bits. The software then accesses a primary address record corresponding to the computer address in a primary address table by using the search index. The primary address record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary address record in a secondary address table. The software then instructs the comparison of the search index to the primary address record. The instructions further include selecting the m low order bits of the combination of the search index and the lower set of m bits to determine a first value. The compressed value of the address contained in the primary address record is then decompressed to obtain a second value. The instructions then compare the first value and the second value and if the first value does not equal the second value, the instructions provide for an initial secondary address record to access via the link. The initial secondary address record includes a respective address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • Still further in accordance with the present invention, there is provided there is provided a method of searching for a computer address in an address table where the computer address having a bit size n. The bit size n computer address is partitioned into an upper set of n-m bits and a lower set of m bits, with m being a value less than bit size n. A search index is then generated by compressing the upper set of n-m bits to obtain a compressed value of the computer address, resulting in the search index having a number of bits equal to the number of bits of the lower set of m bits. An address record corresponding to the computer address is accessed via an address table. The address record is accessed by using the search index to locate the address record, wherein the address record includes the computer address, and a port number associated with the computer address. The search index is then compared to the address record by selecting the m low order bits of the combination of the search index and the lower set of m bits resulting in a first value. The compressed value of the address contained in the address record is decompressed to obtain a second value. The first and second values are compared to determine if a match has occurred.
  • Yet further in accordance with the present invention, there is provided a method of searching for a computer address having a bit size n in an address table. A search index, having a first number of bits less than the bit size n, is generated by compressing the computer address to obtain a compressed value of the address. At least two primary address records, located using the search index, are then accessed corresponding to an equal number of computer addresses stored in a primary address table. The primary address records include the computer addresses, a port number associated with each of the computer addresses, and a link that specifies the location of an initial secondary address record in a secondary address table. The search index and the primary address records are then simultaneously compared by decompressing the search index to obtain a first value, decompressing the compressed values of the addresses contained in each of the primary address records, and comparing the first value to the values of the addresses of the primary address records. If the first value does not equal any of the values of the addresses of the primary address records, then the initial secondary address record is accessed using the link. The initial secondary address record includes a computer address, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
  • Still yet further in accordance with the present invention, there is provided a method for forwarding a frame to a computer address using classification based upon multiple fields in a header. The header has a first field of bit size n-m and a second field having a bit size m, with m being less than n. The first field of bit size n-m and the second field of bit size m are concatenated into a bit size n. A search index, having a number of bits equal to the number bits of the second field, is then generated by compressing the concatenated bit size n to obtain a compressed value of the concatenated fields. A primary record corresponding to the computer address in a primary table is accessed, the primary record being accessed by using the search index to locate the primary record. The primary record includes the computer address, a port number associated with the computer address, and a link that that specifies the location of an initial secondary record in a secondary table. The search index is compared to the primary record by first selecting the concatenated fields of bit size m of the search index and the second field of bit size m, resulting in a first value. The compressed value of the address contained in the primary record is then decompressed to obtain a second value. The first value is compared to the second value, and if the first value does not equal the second value, then accessing the initial secondary record using the link, wherein the initial secondary record includes a respective computer address entry of the bit size n-m, a port number associated with the computer address, and a link to a subsequent secondary record of the same hash family.
  • Still other aspects and advantages of the present invention will become readily apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the best modes best suited for to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modifications in various obvious aspects all without departing from the invention. Accordingly, the drawing and descriptions will be regarded as illustrative in nature and not as restrictive.
  • DESCRIPTION OF THE DRAWINGS
  • Further objects of this invention, together with additional features contributing thereto and advantages accruing therefrom, will be apparent from the following description of a preferred embodiment of the present invention which is shown in the accompanying drawings with like reference numerals indicating corresponding parts throughout and which is to be read in conjunction with the following drawings, wherein:
  • FIG. 1 is a schematic illustration of a network system.
  • FIG. 2 is a schematic illustration of a switch component of the network system.
  • FIG. 3 is an illustration of a preferred embodiment of a primary address table and a secondary address table.
  • FIG. 3 A is an illustration of an embodiment of a compression of an address utilized by the method of the present invention.
  • FIG. 3B is an illustration of an alternate embodiment of a compression of an address utilized by the method of the present invention.
  • FIG. 4 is an illustration of several hash family chains of address storage records.
  • FIG. 5 A is a flow chart that describes a process of allocating resources for the secondary address table.
  • FIG. 5B shows a first example of a secondary address table that has been allocated in accordance with the process of FIG. 5 A.
  • FIG. 5C shows a second example of a secondary address table that has been allocated in accordance with the process of FIG. 5 A.
  • FIG. 6 is a flow chart that describes frame forwarding mechanisms of the switch component.
  • FIGS. 7A-7D are flow charts that describe a method of searching and populating primary and secondary address tables.
  • These and additional embodiments of the invention may now be better understood by turning to the following detailed description wherein an illustrated embodiment is described.
  • DETAILED DESCRIPTION OF THE INVENTION
  • Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than limitations on the apparatus and methods of the present invention.
  • FIG. 1 schematically illustrates a local area network (LAN) 100 that includes a plurality of computer nodes. The computer nodes are referred to collectively using the reference numeral 105 and individually using the reference numeral 105 followed by a letter suffix. Additional devices, such as printers, scanner, copiers, and other devices, such as multifunction peripherals (MFPs) and fax devices, may also be coupled to the LAN 100. The LAN 100 is described herein in the context of an Ethernet network topology, although the principles described herein could also be applied to other types of network topologies in accordance with the disclosure herein. The LAN 100 could also include one or more signal forwarding devices such as a router, repeater, etc.
  • Each of the computer nodes 105 is centrally connected to a switch 115. The switch 115 includes a plurality of ports 120 a-120 d (collectively, ports 120). The switch 115 is configured to receive one or more incoming frames through a first port 120 and thereafter transmit each frame through one or more other ports 120 so that the frame reaches its intended destination. The switch 115 includes a search module that examines the destination MAC address of the frame and forwards the frame to the correct port 120, as described in more detail below. The search module is preferably implemented using software instructions that are stored within memory of the switch 115. It will be appreciated that the searching and forwarding functions described herein are not limited to a switch and could be implemented in any network device that implements address searching and frame forwarding logic.
  • FIG. 2 schematically illustrates the switch 115 in which an embodiment of the invention may be implemented. As mentioned, the switch 115 includes a representative plurality of ports 120 that are communicatively coupled to the one or more computer nodes 105 (FIG. 1). Although the switch 115 is shown as having only four ports, it will be appreciated that the number of ports 120 could vary. As mentioned, the switch 115 includes a memory that stores a search module 210 that is configured to examine and process the source and/or destination MAC address of incoming frames and to determine which port(s) 120 the frame should be forwarded to for the frames to reach the intended destination.
  • With reference to FIG. 2, the switch 115 stores and maintains in memory a primary MAC address table 220 a that is used to store MAC addresses and associated port identifiers. The switch 115 also stores and maintains in memory a secondary MAC address table 220 b that is linked to and used in conjunction with the primary MAC address table 220 a. The secondary MAC address table 220 b is also used to store MAC addresses and associated port identifiers. The primary and secondary MAC address tables 220 preferably each have a predetermined format, as described more fully below. The address tables 220 are described herein in the context of storing a MAC address, although it will be appreciated that the tables 220 could be used to store other embodiments of node addresses for a network system.
  • With reference to FIG. 3, there is shown an illustration of a preferred format of the primary MAC address table 220 a. The primary MAC address table 220 a comprises a data structure that includes a plurality of primary records 305 that are arranged in an array format such that one primary record 305 a in the table 220 a is followed by a successive record 305 b in the table and so on. Each primary record 305 includes an address field for storing a MAC address (either a compressed or a full version), a port field for storing the port identifier with which the MAC address is associated, and a link field for storing a hash family link index that specifies the location of a corresponding secondary record 330 in the secondary MAC address table 220 b or to a null link, as described below. Each primary record 305 could also include additional information related to the MAC address.
  • The primary MAC address table 220 a is preferably indexed as a function of the values of the MAC addresses that are stored within the primary MAC address table 220 a. In a preferred embodiment, a hashing function is performed on all stored MAC addresses and the hashed value of each MAC address is used as an index for locating the particular primary record 305 in which that MAC address is stored. Thus, the contents of each primary record 305 may be accessed using a primary index that points to the memory location of the particular primary record 305. In such a case, the value of the primary index is equal to the hashed value of the MAC address that is stored within that primary record 305.
  • It is possible that several different MAC addresses could map to the exact same hash value and, therefore, map to the same primary record 305 in the primary MAC address table 220 a. MAC addresses that map to the same value are referred to herein as belonging to the same “hash family.” Thus, for example, if MAC addresses 100 and 200 both map to the same hash value, then the addresses 100 and 200 belong to the same hash family. This may result in collisions during indexing of the primary MAC address table 220 a, as two different MAC addresses would have the same primary index. The likelihood of collisions occurring is a function of the hash algorithm as well as a function of the amount of compression of the MAC address that occurs during the hash. A greater amount of compression results in less likelihood of collisions than a lesser amount of compression. In one embodiment, the MAC addresses are hashed to a bit width of 16 bits, although the compression width can be any width less than the original width. For a compression to 16 bits, there are 65,536 possible hash families.
  • For example, FIG. 3 A depicts a particular embodiment of the determination of the primary index using hashing. As shown in FIG. 3A, a full computer address 350 has a size of n bits. Compressing the MAC address 350 results in an index a 352 of a size of m bits, with m being of a substantially smaller size than n. The index a then links to a corresponding record 305 in the primary address table 220 a. As an alternate embodiment, there is shown in FIG. 3B a hybrid hashing method for use in the present invention. A MAC address 354 is partitioned into two smaller components, an upper n-m bit component 356 and a lower m bit component 358. The n-m bit component 356 is then compressed to provide an index a 360 of m bit size. To access the corresponding primary record 305 of the primary address table 220 a, the search index a 360 is compared to the primary record 305 by selecting the low order bits of size m 358 combined with the search index a 360. The value of the address in the primary record 305 is then decompressed and the two values are compared, as discussed in further detail below.
  • Each primary record 305 can be linked to a corresponding secondary record 330 in the secondary MAC address table 220 b. If linked, a primary record 305 is preferably linked to a chain of one or more secondary records 330 that store MAC addresses of the same hash family as is stored in the primary record 305. Thus, MAC addresses of the same hash family are stored within the same hash family chain of linked primary and secondary records 305, 330. As used herein, the term “hash family chain” refers to a linked chain of at least one primary record and possibly one or more secondary records, wherein the linked records all store addresses of the same hash family. The memory location of the first secondary record 330 in such a hash family chain is specified in the hash family link field of the primary record 305 in the chain. If the MAC address in a primary record 305 belongs to a hash family chain comprised of only one record, the primary record 305 is preferably linked to a null pointer.
  • Preferably, the primary MAC address table 220 a is sized to store at least as many primary records 305 as there are hash families. In one embodiment, the primary MAC address table 220 a is configured to store at least 64 k (65,536) primary records 305. The primary MAC address table is preferably stored in a memory that is external to the switch 115. The size or width of each primary record 305 is preferably selected to be less than or equal to the bus width of the external memory.
  • FIG. 3 also shows a schematic illustration of a preferred format for the Primary MAC address table 220 a and secondary MAC address table 220 b. The secondary MAC address table 220 b comprises a data structure that includes a plurality of secondary records 330 arranged in an array format. Each secondary record 330 includes an address field for storing a MAC address, a port field for storing the port identifier with which the MAC address is associated, and a hash family link field that contains a hash family link that specifies the location of another secondary record 330 that stores a MAC address of the same hash family. In an initial state, the hash family link field contains a null pointer. Additionally, the last secondary record 330 in each hash family chain is preferably linked to a null pointer to indicate the end of the hash family chain.
  • The secondary MAC address table 220 b is preferably located in memory that is internal to the switch 115. The secondary MAC address table 220 b is preferably also smaller in size than the primary MAC address table 220 a. In one embodiment, the secondary MAC address table 220 b is sized to store 2,048 secondary records 330. In another embodiment content addressable memory is used for the secondary address table 220 b. Content addressable memory includes comparison logic with each bit stored. Thus, content addressable memory may be used for the secondary address table 220 b, housing only those records 330 a-g that cannot fit into the primary address table 220 a because those records 330 a-g collide with other records that has to the same row in the primary address table 220 a. It will be appreciated by those skilled in the art that the present application may be suitably adapted to high traffic operations, where the high volume of transiting packets warrants the exclusion of a secondary address table, thereby resulting in faster throughput, with a higher collision rate.
  • FIG. 3 shows an exemplary embodiment of the primary MAC address table 220 a and the secondary MAC address table 220 b both being at least partially populated with data. The primary MAC address table 220 a is populated with MAC addresses 100, 200, 300, 400 in primary records 305 a-305 d, respectively. The secondary MAC address table 220 b is populated with MAC addresses A, B, C, D, E, F, and G in secondary records 330 a-330 g, respectively. The index values of the secondary records 330 a-330 g are 1-7, respectively.
  • Assume that MAC addresses 100, A, B, and C are of the same hash family; MAC addresses 200, D, and E are of the same hash family; MAC address 300, F and G are of the same hash family; and MAC address 400 is in its own hash family. Therefore, there are four separate hash family chains contained in the exemplary tables 220 a and 220 b, as shown in FIG. 4.
  • With reference to FIG. 4, a first hash family chain 403 is comprised of primary record 305 a and secondary records 330 a, 330 b, and 330 c all linked in series. As shown in FIG. 3, the hash family link field in primary record 305 a contains the index (1) of secondary record 330 a, which is the next record in the chain. Moving forward through the chain, the hash family link field of secondary record 330 a contains the index (2) of secondary record 330 b. Likewise, the hash family link field of the secondary record 330 b contains the index (3) of secondary record 330 c, the next (and last) record in the hash family chain. Finally, secondary record 330 c contains a null value in its hash family link field, indicating that secondary record 330 c is the last record in the hash family chain 403.
  • Similarly, as shown in FIG. 4, a second hash family chain 407 is comprised of primary record 305 b and secondary records 330 d and 330 e, which are all linked in series. As shown in FIG. 3, the hash family link fields of the primary records 305 b and secondary records 330 d and 330 e each contain the index to the next record in the hash family chain 407. Secondary record 330 e, as the last record in the chain, is linked to a null pointer.
  • As shown in FIG. 4, primary record 305 c and secondary records 330 f and 330 g collectively form yet a third hash family chain 409. Primary record 305 d is the sole link in a fourth hash family chain 411 and is linked to a null pointer, as indicated by the null value in its hash family link field (FIG. 3).
  • FIG. 5 A is a flow chart that describes a process of allocating resources for the secondary MAC address table 220 b. In an initial step 503, an array of unpopulated secondary records is formed in internal memory of the switch 115. Preferably, at least one of the records in the array is reserved as a null record. In a preferred embodiment, 0 is used as NULL pointer. Next, in step 507, the secondary records are all linked in series to thereby form a resource allocation chain comprised of all of the secondary records linked in a single chain. The first record in the resource allocation chain is referred to as the start record and the last record in the chain (not including the null record) is referred to as the end record.
  • In step 509, the switch 115 memorizes the memory address for the start record and the end record of the resource allocation chain. It will be appreciated that addresses of the start record and the end record in the resource allocation chain may change as the secondary MAC address table 220 b is populated and maintained. The switch 115 preferably keeps track of such address changes so that the addresses for the start and end records of the resource allocation chain are constantly updated.
  • In step 511, the end record of the resource allocation chain is linked to the null record. The resource allocation process then ends.
  • An example of a secondary address table 220 b that has been allocated in accordance with the aforementioned resource allocation process is illustrated in FIG. 5B. FIG. 5 b shows an exemplary secondary address table 220 b having six secondary records designated with indices of 0 through 5. The secondary record with index 0 is reserved as the null record. The start record is the secondary record with index 1 and the end record is the secondary record with index 5 so that the resource allocation chain is comprised of secondary records 1, 2, 3, 4, and 5, linked in that order. The end record is linked to the null record.
  • It will be appreciated that the secondary records in the resource allocation chain need not be maintained in consecutive order. For example, FIG. 5C shows the resource allocation chain being comprised of secondary records 1, 4, 5, 2, and 3, lined in that order. In this example, record 1 is the start record and record 3 is the end record.
  • FIG. 6 is a flow chart that generally describes the frame forwarding mechanism for the switch 115. In the first step 605, the switch 115 receives an incoming frame through a particular port 120. The switch 115 next examines the source address portion of the frame and obtains the MAC address of the node from which the frame originated (step 610).
  • In step 615, the switch 115 invokes the search module 210 to search the MAC address tables 220 and determine whether the source address is present in the tables (step 620). The source address is first hashed to obtain the primary search index that is used to access a primary record 305 in the primary MAC address table 220 a. The searching process is described in more detail with respect to FIGS. 7A-7D.
  • If the source address is not present in the MAC address tables 220, the tables 220 are populated with information related to the source MAC address (step 625). The information preferably includes: (1) the source address of the frame; (2) the port number corresponding to the source address; and (3) any other relevant information, such as the age of the source address. For example, assume that node 105 a (FIG. 1) has a MAC address of 100. If the incoming frame originates from node 105 a, the switch 115 would populate the MAC address tables 220 with the MAC address 100 and the port identifier for port 120 a. In this manner, the switch “learns” the MAC addresses and corresponding ports.
  • The reason that a particular source address would not be present in the tables 220 could vary. For example, the switch 115 could be new on the network, the sending device could be new on the network, or the sending device could have been quiet recently (i.e., the sending device has not recently sent a frame).
  • The switch 15 may use the age entry of the MAC address table as a means of periodically maintaining the size of the MAC address table. For example, if the age of the MAC address entry has exceeded a predetermined time limit, then the switch could remove the entry from the MAC address table. This would conserve memory and also improve access speed because fewer entries need to be examined.
  • If the search module 210 finds that the source address is indeed present in the MAC address tables 220, the switch 115 then obtains the destination MAC address from the frame (step 630). The switch 115 then invokes the search module 210 to search the MAC address tables 220 (step 635), in accordance with the method described below with respect to FIG. 5. Depending upon whether the destination MAC address is present in the MAC address tables 220, the frame is then forwarded through the appropriate port(s) 120 or discarded in a conventional manner.
  • For example, if the MAC address is not found in the MAC address tables 220, the switch 115 forwards the frame to all ports to ensure that the frame eventually gets to its recipient. If the destination MAC address is found in the MAC address tables 120, the switch 115 obtains the details of the destination MAC address from the tables 120 including which port that the destination MAC address is associated with. The switch 115 then sends the frame out through the appropriate port 120.
  • If the port associated with the destination MAC address is the same as the port through which the frame was received, then the switch 115 preferably filters the frame (i.e., discards the frame). The frame is discarded because the source node and the destination node are both located on the same shared segment of the LAN. Thus, the frame would have already been transmitted to the destination address without having to travel through the switch 115.
  • FIGS. 7A-7C show flow charts that describe a process by which search module searches the MAC address tables 220 and also learns MAC address information using the MAC address tables 220. The switch 115 preferably includes hardware and/or software that are configured to implement the described process. With reference to FIG. 7A, in the first step 705, the search module 210 obtains a MAC address (the “incoming address”) from a frame. In the context of the Ethernet standard, an exemplary frame includes several fields, including a field for the destination address and the source address of the frame. The search module 210 obtains the MAC address in a well-known manner.
  • In step 710, the search module 210 hashes the incoming MAC address to generate the primary index. The search module preferably hashes the incoming MAC address to a size smaller than the 48 bit size of a full MAC address. The incoming MAC address may be hashed using a hashing function that uses the value of the incoming MAC address to output a compressed or hashed value.
  • In step 715, the search module 210 uses the primary index to locate and retrieve a primary record 305 in the primary MAC address table 220 a. In other words, the hashed value of the incoming MAC address is used to locate a primary record 305 in the primary MAC address table 220 a. For reference purposes, the located primary record will be referred to as primary record 305 a.
  • The search module 210 then examines the primary record 305 a and determines whether the primary record 305 a is empty or populated with data (step 720). If the primary record 305 a is empty, it means that a hash family chain does not yet exist for the incoming MAC address. If this is the case, the search module 210 then proceeds to process B (FIG. 5B), where the search module establishes the first link in a new hash family chain by populating the primary record 305 a with information associated with the incoming MAC address.
  • With reference to FIG. 7B, in step 725, the search module 210 begins populating the primary record 305 a with the MAC address data. In step 730, the search module 210 populates the MAC address field (FIG. 3) of the primary record 305 a with the incoming MAC address. In step 735, the search module populates the port field (FIG. 3) with an identifier for the port that is associated with the incoming MAC address. In step 740, the search module 210 sets the link field (FIG. 3) in the primary record 305 a to a null value, thereby indicating that the primary record 305 a is currently the only record in this particular hash family chain. Alternately, the link field could have a default value of null and remain so until changed. In this manner, the search module has established a new hash family chain with the primary record 305 a being the first (and only) link in the chain. The process is the complete.
  • Returning again to step 720 of FIG. 7A, the search module 210 may discover that the primary record 305 a is already populated with data. This means that a hash family chain already exists for the incoming MAC address, although the number of links in the chain is unknown. If this is the case, the search module 210 proceeds to process C, which is described in FIG. 7C.
  • With reference now to FIG. 7C, the illustrated flow chart describes the performance of the search module 210 where the primary record 305 a is already populated with data. In step 745, the search module compares the incoming MAC address to the MAC address that is stored in the record (the “retrieved address”) and determines whether the addresses are the same. If the incoming address is indeed the same as the retrieved address, then a match has been found. The search module 210 then obtains the data from primary record 305 a (step 747) and the process is complete.
  • However, if the incoming MAC address does not match the retrieved address, then a collision has occurred and the process proceeds to step 749. This means that two different MAC addresses have hashed to the same primary index value. In other words, two different MAC addresses of the same hash family are mapped to primary record 305 a. In step 749, the search module examines the link field of the primary record 305 a and determines whether the link field has a null value.
  • If the link field indeed contains a null value, then it means that the primary record 305 a is currently the only record in the hash family chain for that record and the search module 210 should proceed to establish a new record in the hash family chain. The new record in the chain will store the incoming MAC address.
  • The process then proceeds to step 751, where the search module 210 uses the resource allocation chain (discussed above with respect to FIGS. 5A-5C) of the secondary address table 220 b to retrieve a secondary record for storing the incoming MAC address and appending to the hash family chain. The secondary record that is retrieved is referred to herein as a “retrieved secondary record.” The search module 210 preferably uses the start record in the resource allocation chain as the retrieved secondary record.
  • In step 753, the search module 210 populates the address field and the port field of the retrieved secondary record with the appropriate information related to the incoming MAC address. The search module 210 also populates the hash family link field with a null value thereby indicating that the retrieved secondary record is now the last link in the hash family chain.
  • Next, in step 755, the search module sets the hash family link field of the primary record 305 a to the point to the location of the retrieved secondary record. In this manner, the primary record 305 a and the retrieved secondary record are linked as two records in the same hash family chain.
  • In step 757, the search module updates the resource allocation chain to reflect that the retrieved secondary record has been populated with new data. Additionally, the next consecutive secondary record (FIG. 5B, 2) in the resource allocation chain after the retrieved secondary record is designated as the new start secondary record. The process is then complete.
  • Returning again to step 749 of FIG. 7C, the search module 210 may discover that the primary record 305 a does not contain a null value for its hash family link but rather contains a pointer to a secondary record. This means that the primary record 305 a is already linked to one or more secondary records in a hash family chain. If so, the search module 210 then proceeds to process D, which is described with respect to FIG. 7D.
  • Referring now to FIG. 7D, in step 765 the search module retrieves a secondary record (the “retrieved secondary record”) using the hash family link that is contained in the primary record 305 a. The retrieved secondary record is the next record in the hash family chain for the incoming MAC address. The search module 210 then retrieves the MAC address contained in the retrieved secondary record. In step 767, the search module determines whether the retrieved address matches the incoming address. If the incoming address is indeed the same as the retrieved address, then a match has been found. The search module 210 then obtains the data from the retrieved secondary record (step 769) and the process is complete.
  • However, if the retrieved address does not match the incoming address, then the process proceeds to step 771. In step 771, the search module examines the hash family link field of the retrieved secondary record and determines whether the link field has a null value. If the link field does not contains a null value, then it means that additional secondary records are linked to the current hash family chain. If this is the case, the search module uses the hash family link that is specified in the hash family link field to retrieve the next secondary record in the hash family chain (step 765). The search module loops through steps 765, 767, and 771 until either a match is found in step 767 or a null link is found in step 771.
  • Returning to step 771, if the hash family link field does indeed contain a null value, then it means that the retrieved secondary record is the last record in the hash family chain. Therefore, the search module 210 should proceed to append yet another record to the end of the hash family chain for storing the incoming MAC address.
  • The process then proceeds to step 773, where the search module 210 uses the resource allocation chain of the secondary address table 220 b to retrieve a new secondary record for appending to the hash family chain. The search module 210 preferably uses the start record in the resource allocation chain as the new secondary record.
  • In step 775, the search module 210 populates the address field and the port field of the new secondary record with the appropriate information related to the incoming MAC address. The search module 210 also populates the hash family link field with a null value thereby indicating that the retrieved secondary record is now the last link in the hash family chain.
  • Next, in step 777, the search module 210 sets the hash family link field of the previous secondary record in the hash family chain (the one with null pointer) to point to the location of the new secondary record that now stores the incoming MAC address. In this manner, the hash family chain has been extended by an additional record.
  • In step 779, the search module 210 updates the resource allocation chain to reflect that the retrieved secondary record has been populated with new data. Additionally, the next consecutive secondary record in the resource allocation chain after the retrieved secondary record is designated as the new start secondary record. The process is then complete. In alternate embodiment, the present invention may be applied to multi-field i classifications by concatenating both a 48-bit MAC address and a 12-bit VLAN identifier. A combined 60-bit value may be used to generate a search index. It will be appreciated by those skilled in the art that the use of two fields is exemplary only. Additional fields contained in a data packet header may also be used, thereby further reducing the likelihood of collision. The skilled artisan will further appreciate that concatenation may be accomplished prior to the combination of multiple fields. Thus, each field may be hashed individually, then subsequently concatenated into a larger, albeit compressed value. The concatenated result may then be further hashed, thereby reducing the size of the search index and further reducing the likelihood of collision.
  • While the foregoing examples and preferred embodiments utilized a single row of addresses in the primary address table, those skilled in art will appreciate that multiple addresses stored in a single row of the primary address table provide additional benefits to the application of the subject invention. Thus, simultaneously comparing the two or more addresses stored in a single row with the search index reduces the amount of time spent search for the correct computer address. Additionally, the secondary address table, if needed at all, is substantially reduced in size as a result of the associative caching of the primary address table.
  • Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit of the present invention. All such changes, modifications and alterations should therefore be seen as within the scope of the present invention.

Claims (22)

1-17. (canceled)
18. A method of searching for a computer address in an address table, the steps comprising:
partitioning the computer address into an upper set and a lower set;
generating a search index by compressing the computer address, wherein the search index comprises a number of bits equal to the number of bits of the lower set;
accessing a primary address record corresponding to the computer address in a primary address table, the primary address record being accessed by using the search index to locate the primary address record, wherein the primary address record includes the computer address, a port number associated with the computer address, and a link that specifies the location of an initial secondary address record in a secondary address table; and
comparing the search index to the primary address record.
19. The method of claim 18, wherein comparing the search index to the primary address record includes at least the following:
selecting at least one low order bit of the combination of the search index and the lower set, wherein a first value is determined;
decompressing the compressed value of the address contained in the primary address record to obtain a second value; and
comparing the first value to the second value.
20. The method of claim 18, further comprising, if the first value does not equal the second value, accessing the initial secondary address record, wherein the initial secondary address record includes a respective address entry, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
21. The method of claim 18, wherein the primary address table is stored in a memory external to the switch and wherein the secondary address table is stored in content addressable memory.
22. The method of claim 18, wherein the step of generating a search index by compressing the computer address further comprises at least one of the following: compressing the computer address from a width of 48 bits to a width of less than 48 bits and compressing the computer address from a width of 48 bits to a width of 16 bits.
23. The method of claim 18, further comprising the step of comparing the first value to the computer address in a secondary record.
24. The method of claim 23, further comprising, if the subsequent secondary record is empty, populating the initial secondary address record with the location of the subsequent secondary address record.
25. The method of claim 18, wherein the computer address comprises 60 bits, the upper set comprises 48 bits and the lower set comprises 12 bits.
26. A storage and search unit for computer addresses each having a fixed bit size n, the unit comprising:
a primary address table stored within a first memory the primary address table configured to store a plurality of primary address records, each primary address record including a respective address entry a port number associated with the compressed address entry and a first link that links at least one primary address record to a corresponding chain of secondary address records in a secondary address table;
a secondary address table stored within a second memory separate from the first memory, the secondary address table configured to store a plurality of secondary address records, each secondary address record including a respective address entry a port number associated with the computer address, and a link that links at least one secondary address record to a corresponding secondary address record in the secondary address table to thereby form one or more linked chains of secondary address records;
a software search module configured to store and access the primary address records and secondary address records.
27. The storage and search unit of claim 26, wherein the second memory comprises a content addressable memory.
28. The storage and search unit of claim 26, wherein the bus width of the first memory is 16 bits.
29. The storage and search unit of claim 26, wherein the bit size of the compressed address entry is equal to the bus width of the first memory.
30. The storage and search unit of claim 29, wherein the storage and search unit comprises a switch on an Ethernet network.
31. A computer-readable medium that includes computer-readable software, the computer-readable software including a set of instructions for causing the device to perform at least the following:
search for a computer address in an address table;
partition the computer address into an upper set and a lower set;
generate a search index by compressing the upper set to obtain a compressed value of the computer address;
access a primary address record corresponding to the computer address in a primary address table, the primary address record being accessed by using the search index to locate the primary address record; and
compare the search index to the primary address.
32. The computer-readable medium of claim 31, wherein comparing the search index to the primary address includes at least the following:
select the order bits of the combination of the search index and the lower set, wherein a first value is determined,
decompress the compressed value of the address contained in the primary address record to obtain a second value; and
comparing the first value to the second value.
33. The computer-readable medium of claim 31, the set of instructions further configured to cause the device to perform at least the following:
if the first value does not equal the second value, then access the initial secondary address record using the link, wherein the initial secondary address record includes a respective address entry of the first bit size less than the fixed bit size n, a port number associated with the computer address, and a link to a subsequent secondary address record of the same hash family.
34. The computer-readable medium of claim 31, wherein the set of instructions is further configured to perform at least the following: compress the computer address from a width of 48 bits to a width of less than 48 bits.
35. The computer-readable medium of claim 31, wherein the set of instructions is further configured to perform at least the following: compress the computer address from a width of 48 bits to a width of 16 bits.
36. The computer-readable medium of claim 31, wherein the set of instructions is further configured to perform at least the following: compare the first value to the full computer address in the secondary record.
37. The computer-readable medium of claim 36, wherein the set of instructions is further configured to perform at least the following: if the subsequent secondary record is empty to populate the subsequent secondary record with the computer address and with a port associated with the computer address.
38. The computer-readable medium of claim 37 wherein the set of instructions is further configured to perform at least the following: if the subsequent secondary record is empty, populate the initial secondary address record with the location of the subsequent secondary address record.
US12/107,567 2000-08-22 2008-04-22 High-Speed MAC Address Search Engine Abandoned US20090031044A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US12/107,567 US20090031044A1 (en) 2000-08-22 2008-04-22 High-Speed MAC Address Search Engine

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US09/643,567 US6697873B1 (en) 1999-12-20 2000-08-22 High speed MAC address search engine
US10/750,445 US7373425B2 (en) 2000-08-22 2003-12-31 High-speed MAC address search engine
US12/107,567 US20090031044A1 (en) 2000-08-22 2008-04-22 High-Speed MAC Address Search Engine

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US10/750,445 Continuation US7373425B2 (en) 2000-08-22 2003-12-31 High-speed MAC address search engine

Publications (1)

Publication Number Publication Date
US20090031044A1 true US20090031044A1 (en) 2009-01-29

Family

ID=46300630

Family Applications (2)

Application Number Title Priority Date Filing Date
US10/750,445 Expired - Lifetime US7373425B2 (en) 2000-08-22 2003-12-31 High-speed MAC address search engine
US12/107,567 Abandoned US20090031044A1 (en) 2000-08-22 2008-04-22 High-Speed MAC Address Search Engine

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US10/750,445 Expired - Lifetime US7373425B2 (en) 2000-08-22 2003-12-31 High-speed MAC address search engine

Country Status (1)

Country Link
US (2) US7373425B2 (en)

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050021786A1 (en) * 2002-02-28 2005-01-27 Norifumi Kikkawa Device authentication apparatus device authentication method information processing apparatus information processing method and computer program
US20070160046A1 (en) * 2005-10-13 2007-07-12 Matta Sudheer P C System and method for reliable multicast
US20070183375A1 (en) * 2005-10-13 2007-08-09 Manish Tiwari System and method for network integrity
US20070189222A1 (en) * 2004-02-13 2007-08-16 Trapeze Networks, Inc. Station mobility between access points
US20070189278A1 (en) * 2006-01-31 2007-08-16 Ming-Hsu Tu System and method for compressing voice over IP headers
US20070287390A1 (en) * 2006-06-09 2007-12-13 Trapeze Networks, Inc. Untethered access point mesh system and method
US20080069018A1 (en) * 2006-09-15 2008-03-20 Trapeze Networks, Inc. Quality of service provisioning for wireless networks
US20080096575A1 (en) * 2006-10-16 2008-04-24 Trapeze Networks, Inc. Load balancing
US20080114784A1 (en) * 2006-06-09 2008-05-15 James Murphy Sharing data between wireless switches system and method
US20080117822A1 (en) * 2006-06-09 2008-05-22 James Murphy Wireless routing selection system and method
US20080151844A1 (en) * 2006-12-20 2008-06-26 Manish Tiwari Wireless access point authentication system and method
US20080162921A1 (en) * 2006-12-28 2008-07-03 Trapeze Networks, Inc. Application-aware wireless network system and method
US20080226075A1 (en) * 2007-03-14 2008-09-18 Trapeze Networks, Inc. Restricted services for wireless stations
US20090067436A1 (en) * 2007-09-07 2009-03-12 Trapeze Networks, Inc. Network assignment based on priority
US20090131082A1 (en) * 2007-11-21 2009-05-21 Trapeze Networks, Inc. Wireless station location detection
US20090141651A1 (en) * 2007-12-03 2009-06-04 White Russell I Determining an optimal route advertisement in a reactive routing environment
US20090198999A1 (en) * 2005-03-15 2009-08-06 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US20090257437A1 (en) * 2005-10-13 2009-10-15 Trapeze Networks, Inc. Identity-based networking
US20090323531A1 (en) * 2006-06-01 2009-12-31 Trapeze Networks, Inc. Wireless load balancing
US20100067379A1 (en) * 2008-08-29 2010-03-18 Trapeze Networks, Inc. Picking an optimal channel for an access point in a wireless network
US20100180016A1 (en) * 2006-05-19 2010-07-15 Belden Inc. Automated network device configuration and network deployment
US20100208740A1 (en) * 2009-02-18 2010-08-19 Funai Electric Co., Ltd. Communication Apparatus and Communication System
US20110128858A1 (en) * 2005-10-13 2011-06-02 Trapeze Networks, Inc. System and network for wireless network monitoring
US8150357B2 (en) 2008-03-28 2012-04-03 Trapeze Networks, Inc. Smoothing filter for irregular update intervals
US8218449B2 (en) 2005-10-13 2012-07-10 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US20130046922A1 (en) * 2011-03-31 2013-02-21 International Business Machines Corporation Content addressable memory and method of searching data thereof
US20130086073A1 (en) * 2011-09-29 2013-04-04 International Business Machines Corporation Rejecting rows when scanning a collision chain
US8474023B2 (en) 2008-05-30 2013-06-25 Juniper Networks, Inc. Proactive credential caching
US8670383B2 (en) 2006-12-28 2014-03-11 Trapeze Networks, Inc. System and method for aggregation and queuing in a wireless network
US8964747B2 (en) 2006-05-03 2015-02-24 Trapeze Networks, Inc. System and method for restricting network access using forwarding databases
US8978105B2 (en) 2008-07-25 2015-03-10 Trapeze Networks, Inc. Affirming network relationships and resource access via related networks
US9258702B2 (en) 2006-06-09 2016-02-09 Trapeze Networks, Inc. AP-local dynamic switching
US9565035B1 (en) 2010-05-26 2017-02-07 Marvell International Ltd. Enhanced audio video bridging (AVB) methods and apparatus
US10366068B2 (en) 2014-12-18 2019-07-30 International Business Machines Corporation Optimization of metadata via lossy compression
US10649991B2 (en) 2016-04-26 2020-05-12 International Business Machines Corporation Pruning of columns in synopsis tables

Families Citing this family (82)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8369264B2 (en) * 2005-10-28 2013-02-05 Skyhook Wireless, Inc. Method and system for selecting and providing a relevant subset of Wi-Fi location information to a mobile client device so the client device may estimate its position with efficient utilization of resources
ES2391566T3 (en) 2004-10-29 2012-11-27 Skyhook Wireless, Inc. Database and location beacon server, method to build a location beacon database, and location-based service that uses it
JP4704043B2 (en) * 2005-01-07 2011-06-15 富士通株式会社 Movement processing program, information processing apparatus, computer system, and computer-readable recording medium storing movement processing program
US8228932B2 (en) * 2005-02-18 2012-07-24 Broadcom Corporation Layout architecture for expandable network device
US7502620B2 (en) * 2005-03-04 2009-03-10 Shyhook Wireless, Inc. Encoding and compression of a location beacon database
EP1851979B1 (en) 2005-02-22 2018-06-13 Skyhook Wireless, Inc. Method of continuous data optimization in a positioning system
US7571332B2 (en) * 2005-06-13 2009-08-04 Lenovo (Singapore) Pte. Ltd. Reducing power consumed by a computer system during a hibernation or an off state by remotely waking up the computer system
US7606232B1 (en) 2005-11-09 2009-10-20 Juniper Networks, Inc. Dynamic virtual local area network (VLAN) interface configuration
US7808994B1 (en) * 2006-02-22 2010-10-05 Juniper Networks, Inc. Forwarding traffic to VLAN interfaces built based on subscriber information strings
US7492766B2 (en) * 2006-02-22 2009-02-17 Juniper Networks, Inc. Dynamic building of VLAN interfaces based on subscriber information strings
US7471954B2 (en) * 2006-02-24 2008-12-30 Skyhook Wireless, Inc. Methods and systems for estimating a user position in a WLAN positioning system based on user assigned access point locations
US8014788B2 (en) * 2006-05-08 2011-09-06 Skyhook Wireless, Inc. Estimation of speed of travel using the dynamic signal strength variation of multiple WLAN access points
US7551579B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Calculation of quality of wlan access point characterization for use in a wlan positioning system
US7835754B2 (en) * 2006-05-08 2010-11-16 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system
US7551929B2 (en) * 2006-05-08 2009-06-23 Skyhook Wireless, Inc. Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations
JP2009543074A (en) 2006-07-07 2009-12-03 スカイフック ワイヤレス,インク. System and method for collecting information from a WLAN-enabled access point to estimate the location of a WLAN positioning device
CN101523862A (en) * 2006-08-04 2009-09-02 探空气球无线公司 Systems and methods of automated retrieval of location information from a user device for use with server systems
US7856234B2 (en) * 2006-11-07 2010-12-21 Skyhook Wireless, Inc. System and method for estimating positioning error within a WLAN-based positioning system
US20080248808A1 (en) * 2007-04-05 2008-10-09 Farshid Alizadeh-Shabdiz Estimation of position, speed and bearing using time difference of arrival and received signal strength in a wlan positioning system
JP4946803B2 (en) * 2007-11-01 2012-06-06 富士通株式会社 Packet relay method and apparatus
EP2283641B1 (en) 2008-06-06 2020-08-12 Skyhook Wireless, Inc. Method and system for determining location using a hybrid satellite and wlan positioning system by selecting the best wlan-ps solution
US8155666B2 (en) 2008-06-16 2012-04-10 Skyhook Wireless, Inc. Methods and systems for determining location using a cellular and WLAN positioning system by selecting the best cellular positioning system solution
CN101478608A (en) * 2009-01-09 2009-07-08 南京联创科技股份有限公司 Fast operating method for mass data based on two-dimensional hash
US8406785B2 (en) 2009-08-18 2013-03-26 Skyhook Wireless, Inc. Method and system for estimating range of mobile device to wireless installation
US8638256B2 (en) 2009-09-29 2014-01-28 Skyhook Wireless, Inc. Accuracy and performance of a hybrid positioning system
US8619643B2 (en) 2010-03-24 2013-12-31 Skyhook Wireless, Inc. System and method for estimating the probability of movement of access points in a WLAN-based positioning system
US9716672B2 (en) 2010-05-28 2017-07-25 Brocade Communications Systems, Inc. Distributed configuration management for virtual cluster switching
US9270486B2 (en) 2010-06-07 2016-02-23 Brocade Communications Systems, Inc. Name services for virtual cluster switching
US9769016B2 (en) 2010-06-07 2017-09-19 Brocade Communications Systems, Inc. Advanced link tracking for virtual cluster switching
US8867552B2 (en) 2010-05-03 2014-10-21 Brocade Communications Systems, Inc. Virtual cluster switching
US9628293B2 (en) 2010-06-08 2017-04-18 Brocade Communications Systems, Inc. Network layer multicasting in trill networks
US9806906B2 (en) 2010-06-08 2017-10-31 Brocade Communications Systems, Inc. Flooding packets on a per-virtual-network basis
US9608833B2 (en) 2010-06-08 2017-03-28 Brocade Communications Systems, Inc. Supporting multiple multicast trees in trill networks
US8700053B2 (en) 2010-06-11 2014-04-15 Skyhook Wireless, Inc. Systems for and methods of determining likelihood of relocation of reference points in a positioning system
US9807031B2 (en) 2010-07-16 2017-10-31 Brocade Communications Systems, Inc. System and method for network configuration
US8606294B2 (en) 2010-10-05 2013-12-10 Skyhook Wireless, Inc. Method of and system for estimating temporal demographics of mobile users
KR101972606B1 (en) 2010-11-03 2019-04-25 스카이후크 와이어리스, 인크. Method of system for increasing the reliability and accuracy of location estimation in a hybrid positioning system
US20120331561A1 (en) 2011-06-22 2012-12-27 Broadstone Andrew J Method of and Systems for Privacy Preserving Mobile Demographic Measurement of Individuals, Groups and Locations Over Time and Space
US9736085B2 (en) 2011-08-29 2017-08-15 Brocade Communications Systems, Inc. End-to end lossless Ethernet in Ethernet fabric
US8719450B2 (en) * 2011-10-31 2014-05-06 Cable Television Laboratories, Inc. Internet protocol (IP) address translation
US9699117B2 (en) 2011-11-08 2017-07-04 Brocade Communications Systems, Inc. Integrated fibre channel support in an ethernet fabric switch
US9450870B2 (en) 2011-11-10 2016-09-20 Brocade Communications Systems, Inc. System and method for flow management in software-defined networks
US8995272B2 (en) 2012-01-26 2015-03-31 Brocade Communication Systems, Inc. Link aggregation in software-defined networks
US9742693B2 (en) 2012-02-27 2017-08-22 Brocade Communications Systems, Inc. Dynamic service insertion in a fabric switch
US9154416B2 (en) 2012-03-22 2015-10-06 Brocade Communications Systems, Inc. Overlay tunnel in a fabric switch
US9374301B2 (en) 2012-05-18 2016-06-21 Brocade Communications Systems, Inc. Network feedback in software-defined networks
US10277464B2 (en) 2012-05-22 2019-04-30 Arris Enterprises Llc Client auto-configuration in a multi-switch link aggregation
US10454760B2 (en) 2012-05-23 2019-10-22 Avago Technologies International Sales Pte. Limited Layer-3 overlay gateways
US9602430B2 (en) 2012-08-21 2017-03-21 Brocade Communications Systems, Inc. Global VLANs for fabric switches
US9401872B2 (en) 2012-11-16 2016-07-26 Brocade Communications Systems, Inc. Virtual link aggregations across multiple fabric switches
US9350680B2 (en) 2013-01-11 2016-05-24 Brocade Communications Systems, Inc. Protection switching over a virtual link aggregation
US9548926B2 (en) 2013-01-11 2017-01-17 Brocade Communications Systems, Inc. Multicast traffic load balancing over virtual link aggregation
US9413691B2 (en) 2013-01-11 2016-08-09 Brocade Communications Systems, Inc. MAC address synchronization in a fabric switch
US9565113B2 (en) 2013-01-15 2017-02-07 Brocade Communications Systems, Inc. Adaptive link aggregation and virtual link aggregation
US9565099B2 (en) 2013-03-01 2017-02-07 Brocade Communications Systems, Inc. Spanning tree in fabric switches
US9401818B2 (en) 2013-03-15 2016-07-26 Brocade Communications Systems, Inc. Scalable gateways for a fabric switch
US9699001B2 (en) 2013-06-10 2017-07-04 Brocade Communications Systems, Inc. Scalable and segregated network virtualization
US9565028B2 (en) 2013-06-10 2017-02-07 Brocade Communications Systems, Inc. Ingress switch multicast distribution in a fabric switch
US9912612B2 (en) 2013-10-28 2018-03-06 Brocade Communications Systems LLC Extended ethernet fabric switches
US9548873B2 (en) 2014-02-10 2017-01-17 Brocade Communications Systems, Inc. Virtual extensible LAN tunnel keepalives
US10581758B2 (en) 2014-03-19 2020-03-03 Avago Technologies International Sales Pte. Limited Distributed hot standby links for vLAG
US10476698B2 (en) 2014-03-20 2019-11-12 Avago Technologies International Sales Pte. Limited Redundent virtual link aggregation group
US10063473B2 (en) 2014-04-30 2018-08-28 Brocade Communications Systems LLC Method and system for facilitating switch virtualization in a network of interconnected switches
US9800471B2 (en) 2014-05-13 2017-10-24 Brocade Communications Systems, Inc. Network extension groups of global VLANs in a fabric switch
US10616108B2 (en) 2014-07-29 2020-04-07 Avago Technologies International Sales Pte. Limited Scalable MAC address virtualization
US9544219B2 (en) 2014-07-31 2017-01-10 Brocade Communications Systems, Inc. Global VLAN services
US9807007B2 (en) 2014-08-11 2017-10-31 Brocade Communications Systems, Inc. Progressive MAC address learning
US9524173B2 (en) 2014-10-09 2016-12-20 Brocade Communications Systems, Inc. Fast reboot for a switch
US9699029B2 (en) 2014-10-10 2017-07-04 Brocade Communications Systems, Inc. Distributed configuration management in a switch group
US10798000B2 (en) * 2014-12-22 2020-10-06 Arista Networks, Inc. Method and apparatus of compressing network forwarding entry information
US9626255B2 (en) 2014-12-31 2017-04-18 Brocade Communications Systems, Inc. Online restoration of a switch snapshot
US9628407B2 (en) 2014-12-31 2017-04-18 Brocade Communications Systems, Inc. Multiple software versions in a switch group
US9942097B2 (en) 2015-01-05 2018-04-10 Brocade Communications Systems LLC Power management in a network of interconnected switches
US10003552B2 (en) 2015-01-05 2018-06-19 Brocade Communications Systems, Llc. Distributed bidirectional forwarding detection protocol (D-BFD) for cluster of interconnected switches
US9680749B2 (en) 2015-02-27 2017-06-13 Arista Networks, Inc. System and method of using an exact match table and longest prefix match table as a combined longest prefix match
US9807005B2 (en) 2015-03-17 2017-10-31 Brocade Communications Systems, Inc. Multi-fabric manager
US10038592B2 (en) 2015-03-17 2018-07-31 Brocade Communications Systems LLC Identifier assignment to a new switch in a switch group
US10579406B2 (en) 2015-04-08 2020-03-03 Avago Technologies International Sales Pte. Limited Dynamic orchestration of overlay tunnels
US10439929B2 (en) 2015-07-31 2019-10-08 Avago Technologies International Sales Pte. Limited Graceful recovery of a multicast-enabled switch
US10171303B2 (en) 2015-09-16 2019-01-01 Avago Technologies International Sales Pte. Limited IP-based interconnection of switches with a logical chassis
US9912614B2 (en) 2015-12-07 2018-03-06 Brocade Communications Systems LLC Interconnection of switches based on hierarchical overlay tunneling
US10237090B2 (en) 2016-10-28 2019-03-19 Avago Technologies International Sales Pte. Limited Rule-based network identifier mapping

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5740171A (en) * 1996-03-28 1998-04-14 Cisco Systems, Inc. Address translation mechanism for a high-performance network switch
US5917821A (en) * 1993-12-24 1999-06-29 Newbridge Networks Corporation Look-up engine for packet-based network
US6009423A (en) * 1996-10-30 1999-12-28 3Com Technologies Search apparatus
US6192051B1 (en) * 1999-02-26 2001-02-20 Redstone Communications, Inc. Network router search engine using compressed tree forwarding table
US6266705B1 (en) * 1998-09-29 2001-07-24 Cisco Systems, Inc. Look up mechanism and associated hash table for a network switch
US6295299B1 (en) * 1997-08-29 2001-09-25 Extreme Networks, Inc. Data path architecture for a LAN switch
US6424650B1 (en) * 1999-02-09 2002-07-23 3Com Corporation Network address filter device

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5917821A (en) * 1993-12-24 1999-06-29 Newbridge Networks Corporation Look-up engine for packet-based network
US5740171A (en) * 1996-03-28 1998-04-14 Cisco Systems, Inc. Address translation mechanism for a high-performance network switch
US6009423A (en) * 1996-10-30 1999-12-28 3Com Technologies Search apparatus
US6295299B1 (en) * 1997-08-29 2001-09-25 Extreme Networks, Inc. Data path architecture for a LAN switch
US6266705B1 (en) * 1998-09-29 2001-07-24 Cisco Systems, Inc. Look up mechanism and associated hash table for a network switch
US6424650B1 (en) * 1999-02-09 2002-07-23 3Com Corporation Network address filter device
US6192051B1 (en) * 1999-02-26 2001-02-20 Redstone Communications, Inc. Network router search engine using compressed tree forwarding table

Cited By (78)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050021786A1 (en) * 2002-02-28 2005-01-27 Norifumi Kikkawa Device authentication apparatus device authentication method information processing apparatus information processing method and computer program
US7752289B2 (en) * 2002-09-02 2010-07-06 Sony Corporation Device authentication apparatus device authentication method information processing apparatus information processing method and computer program
US20070189222A1 (en) * 2004-02-13 2007-08-16 Trapeze Networks, Inc. Station mobility between access points
US8635444B2 (en) 2005-03-15 2014-01-21 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US8161278B2 (en) 2005-03-15 2012-04-17 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US20090198999A1 (en) * 2005-03-15 2009-08-06 Trapeze Networks, Inc. System and method for distributing keys in a wireless network
US8514827B2 (en) 2005-10-13 2013-08-20 Trapeze Networks, Inc. System and network for wireless network monitoring
US20090257437A1 (en) * 2005-10-13 2009-10-15 Trapeze Networks, Inc. Identity-based networking
US8638762B2 (en) * 2005-10-13 2014-01-28 Trapeze Networks, Inc. System and method for network integrity
US20070160046A1 (en) * 2005-10-13 2007-07-12 Matta Sudheer P C System and method for reliable multicast
US20070183375A1 (en) * 2005-10-13 2007-08-09 Manish Tiwari System and method for network integrity
US8457031B2 (en) 2005-10-13 2013-06-04 Trapeze Networks, Inc. System and method for reliable multicast
US20110128858A1 (en) * 2005-10-13 2011-06-02 Trapeze Networks, Inc. System and network for wireless network monitoring
US8116275B2 (en) 2005-10-13 2012-02-14 Trapeze Networks, Inc. System and network for wireless network monitoring
US8270408B2 (en) 2005-10-13 2012-09-18 Trapeze Networks, Inc. Identity-based networking
US8218449B2 (en) 2005-10-13 2012-07-10 Trapeze Networks, Inc. System and method for remote monitoring in a wireless network
US20070189278A1 (en) * 2006-01-31 2007-08-16 Ming-Hsu Tu System and method for compressing voice over IP headers
US8284759B2 (en) * 2006-01-31 2012-10-09 Alcatel Lucent System and method for compressing voice over IP headers
US8964747B2 (en) 2006-05-03 2015-02-24 Trapeze Networks, Inc. System and method for restricting network access using forwarding databases
US20100180016A1 (en) * 2006-05-19 2010-07-15 Belden Inc. Automated network device configuration and network deployment
US8966018B2 (en) 2006-05-19 2015-02-24 Trapeze Networks, Inc. Automated network device configuration and network deployment
US8320949B2 (en) 2006-06-01 2012-11-27 Juniper Networks, Inc. Wireless load balancing across bands
US20090323531A1 (en) * 2006-06-01 2009-12-31 Trapeze Networks, Inc. Wireless load balancing
US8064939B2 (en) 2006-06-01 2011-11-22 Juniper Networks, Inc. Wireless load balancing
US9258702B2 (en) 2006-06-09 2016-02-09 Trapeze Networks, Inc. AP-local dynamic switching
US20070287390A1 (en) * 2006-06-09 2007-12-13 Trapeze Networks, Inc. Untethered access point mesh system and method
US8818322B2 (en) 2006-06-09 2014-08-26 Trapeze Networks, Inc. Untethered access point mesh system and method
US10798650B2 (en) 2006-06-09 2020-10-06 Trapeze Networks, Inc. AP-local dynamic switching
US11758398B2 (en) 2006-06-09 2023-09-12 Juniper Networks, Inc. Untethered access point mesh system and method
US10327202B2 (en) 2006-06-09 2019-06-18 Trapeze Networks, Inc. AP-local dynamic switching
US10638304B2 (en) 2006-06-09 2020-04-28 Trapeze Networks, Inc. Sharing data between wireless switches system and method
US11627461B2 (en) 2006-06-09 2023-04-11 Juniper Networks, Inc. AP-local dynamic switching
US9191799B2 (en) 2006-06-09 2015-11-17 Juniper Networks, Inc. Sharing data between wireless switches system and method
US20080114784A1 (en) * 2006-06-09 2008-05-15 James Murphy Sharing data between wireless switches system and method
US9838942B2 (en) 2006-06-09 2017-12-05 Trapeze Networks, Inc. AP-local dynamic switching
US20080117822A1 (en) * 2006-06-09 2008-05-22 James Murphy Wireless routing selection system and method
US11432147B2 (en) 2006-06-09 2022-08-30 Trapeze Networks, Inc. Untethered access point mesh system and method
US10834585B2 (en) 2006-06-09 2020-11-10 Trapeze Networks, Inc. Untethered access point mesh system and method
US7912982B2 (en) 2006-06-09 2011-03-22 Trapeze Networks, Inc. Wireless routing selection system and method
US8340110B2 (en) 2006-09-15 2012-12-25 Trapeze Networks, Inc. Quality of service provisioning for wireless networks
US20080069018A1 (en) * 2006-09-15 2008-03-20 Trapeze Networks, Inc. Quality of service provisioning for wireless networks
US8446890B2 (en) 2006-10-16 2013-05-21 Juniper Networks, Inc. Load balancing
US20080096575A1 (en) * 2006-10-16 2008-04-24 Trapeze Networks, Inc. Load balancing
US8072952B2 (en) 2006-10-16 2011-12-06 Juniper Networks, Inc. Load balancing
US20080151844A1 (en) * 2006-12-20 2008-06-26 Manish Tiwari Wireless access point authentication system and method
US20080162921A1 (en) * 2006-12-28 2008-07-03 Trapeze Networks, Inc. Application-aware wireless network system and method
US8670383B2 (en) 2006-12-28 2014-03-11 Trapeze Networks, Inc. System and method for aggregation and queuing in a wireless network
US7865713B2 (en) 2006-12-28 2011-01-04 Trapeze Networks, Inc. Application-aware wireless network system and method
US20080226075A1 (en) * 2007-03-14 2008-09-18 Trapeze Networks, Inc. Restricted services for wireless stations
US20090067436A1 (en) * 2007-09-07 2009-03-12 Trapeze Networks, Inc. Network assignment based on priority
US8902904B2 (en) 2007-09-07 2014-12-02 Trapeze Networks, Inc. Network assignment based on priority
US20090131082A1 (en) * 2007-11-21 2009-05-21 Trapeze Networks, Inc. Wireless station location detection
US8238942B2 (en) 2007-11-21 2012-08-07 Trapeze Networks, Inc. Wireless station location detection
US8705539B2 (en) 2007-12-03 2014-04-22 Cisco Technology, Inc. Determining a route advertisement in a reactive routing environment
US9191227B2 (en) 2007-12-03 2015-11-17 Cisco Technology, Inc. Determining a route advertisement in a reactive routing environment
US20090141651A1 (en) * 2007-12-03 2009-06-04 White Russell I Determining an optimal route advertisement in a reactive routing environment
US8150357B2 (en) 2008-03-28 2012-04-03 Trapeze Networks, Inc. Smoothing filter for irregular update intervals
US8474023B2 (en) 2008-05-30 2013-06-25 Juniper Networks, Inc. Proactive credential caching
US8978105B2 (en) 2008-07-25 2015-03-10 Trapeze Networks, Inc. Affirming network relationships and resource access via related networks
US8238298B2 (en) 2008-08-29 2012-08-07 Trapeze Networks, Inc. Picking an optimal channel for an access point in a wireless network
US20100067379A1 (en) * 2008-08-29 2010-03-18 Trapeze Networks, Inc. Picking an optimal channel for an access point in a wireless network
US8345572B2 (en) * 2009-02-18 2013-01-01 Funai Electric Co., Ltd. Communication apparatus and communication system
US20100208740A1 (en) * 2009-02-18 2010-08-19 Funai Electric Co., Ltd. Communication Apparatus and Communication System
US9584342B1 (en) 2010-05-26 2017-02-28 Marvell International Ltd. Enhanced audio video bridging (AVB) methods and apparatus
US9887938B1 (en) 2010-05-26 2018-02-06 Marvell International Ltd. Enhanced audio video bridging (AVB) methods and apparatus
US9565035B1 (en) 2010-05-26 2017-02-07 Marvell International Ltd. Enhanced audio video bridging (AVB) methods and apparatus
US10432556B1 (en) 2010-05-26 2019-10-01 Marvell International Ltd. Enhanced audio video bridging (AVB) methods and apparatus
US9590910B1 (en) * 2010-05-26 2017-03-07 Marvell International Ltd. Methods and apparatus for handling multicast packets in an audio video bridging (AVB) network
US20130046922A1 (en) * 2011-03-31 2013-02-21 International Business Machines Corporation Content addressable memory and method of searching data thereof
US8914574B2 (en) * 2011-03-31 2014-12-16 International Business Machines Corporation Content addressable memory and method of searching data thereof
US8903831B2 (en) * 2011-09-29 2014-12-02 International Business Machines Corporation Rejecting rows when scanning a collision chain
US9361307B2 (en) 2011-09-29 2016-06-07 International Business Machines Corporation Rejecting rows when scanning a collision chain that is associated with a page filter
US20130086073A1 (en) * 2011-09-29 2013-04-04 International Business Machines Corporation Rejecting rows when scanning a collision chain
US11216436B2 (en) 2014-12-18 2022-01-04 International Business Machines Corporation Optimization of metadata via lossy compression
US10372698B2 (en) 2014-12-18 2019-08-06 International Business Machines Corporation Optimization of metadata via lossy compression
US10366068B2 (en) 2014-12-18 2019-07-30 International Business Machines Corporation Optimization of metadata via lossy compression
US10691687B2 (en) 2016-04-26 2020-06-23 International Business Machines Corporation Pruning of columns in synopsis tables
US10649991B2 (en) 2016-04-26 2020-05-12 International Business Machines Corporation Pruning of columns in synopsis tables

Also Published As

Publication number Publication date
US20040205234A1 (en) 2004-10-14
US7373425B2 (en) 2008-05-13

Similar Documents

Publication Publication Date Title
US7373425B2 (en) High-speed MAC address search engine
US6697873B1 (en) High speed MAC address search engine
US20050171937A1 (en) Memory efficient hashing algorithm
US7885268B2 (en) Method and system for hash table based routing via table and prefix aggregation
JP4057067B2 (en) Mechanism for replacing packet fields in multi-layer switching network elements
JP3735471B2 (en) Packet relay device and LSI
US7782874B2 (en) Apparatus and method for route summarization and distribution in a massively parallel router
US7260096B2 (en) Method and router for forwarding internet data packets
EP1168723B1 (en) Method and apparatus for longest matching prefix determination in a communication network
US6172980B1 (en) Multiple protocol support
JP3640299B2 (en) A proposal and response architecture for route lookup and packet classification requests
EP0836780B1 (en) Network addressing arrangement for backward compatible routing of an expanded address space
US20030026246A1 (en) Cached IP routing tree for longest prefix search
US20060083247A1 (en) Prefix lookup using address-directed hash tables
US7346059B1 (en) Header range check hash circuit
US20020046291A1 (en) Network unit with address cache for frequently occurring network conversations
US6922410B1 (en) Organization of databases in network switches for packet-based data communications networks
US7313138B2 (en) Router device and routing method
US20020161918A1 (en) Packet transmission system in which packet is transferred without replacing address in the packet
JPH05219064A (en) Method of transferring frame and bridge device
EP3777055B1 (en) Longest prefix matching
WO2002052442A1 (en) Apparatus and method for performing high-speed ip route lookup and managing routing/forwarding tables
US7486672B2 (en) Apparatus and method for searching trie trees using masks with non-symbol boundaries and flooding default routes in a massively parallel router
EP1526699B1 (en) Method and system for accelerated packet processing
US6819671B1 (en) Relay control circuit using hashing function algorithm

Legal Events

Date Code Title Description
AS Assignment

Owner name: ZARLINK SEMICONDUCTOR INC., CANADA

Free format text: CONFIRMATORY ASSIGNMENT;ASSIGNOR:ZARLINK SEMICONDUCTOR V.N. INC.;REEL/FRAME:020917/0880

Effective date: 20040601

Owner name: ZARLINK SEMICONDUCTOR V.N. INC., CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BARRACK, CRAIG;YIK, JAMES CHING-SHAU;CHANG, RONG-FENG;AND OTHERS;REEL/FRAME:020917/0190;SIGNING DATES FROM 20010121 TO 20040121

Owner name: BANK OF NEW YORK TRUST COMPANY, N.A., ILLINOIS

Free format text: SECURITY AGREEMENT;ASSIGNOR:CONEXANT SYSTEMS, INC.;REEL/FRAME:020918/0249

Effective date: 20061113

Owner name: CONEXANT SYSTEMS, INC., NEW JERSEY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ZARLINK SEMICONDUCTOR V.N. INC.;ZARLINK SEMICONDUCTOR, INC.;REEL/FRAME:020918/0204

Effective date: 20061025

AS Assignment

Owner name: CONEXANT SYSTEMS, INC., CALIFORNIA

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.;REEL/FRAME:023134/0249

Effective date: 20090821

Owner name: CONEXANT SYSTEMS, INC.,CALIFORNIA

Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.;REEL/FRAME:023134/0249

Effective date: 20090821

AS Assignment

Owner name: IKANOS COMMUNICATIONS, INC., CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CONEXANT SYSTEMS, INC.;CONEXANT, INC.;BROOKTREE BROADBAND HOLDING INC.;REEL/FRAME:023163/0723

Effective date: 20090824

Owner name: IKANOS COMMUNICATIONS, INC.,CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CONEXANT SYSTEMS, INC.;CONEXANT, INC.;BROOKTREE BROADBAND HOLDING INC.;REEL/FRAME:023163/0723

Effective date: 20090824

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION