CN101267331A - A search method and device for multicast forward table - Google Patents
A search method and device for multicast forward table Download PDFInfo
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- CN101267331A CN101267331A CNA2008100950244A CN200810095024A CN101267331A CN 101267331 A CN101267331 A CN 101267331A CN A2008100950244 A CNA2008100950244 A CN A2008100950244A CN 200810095024 A CN200810095024 A CN 200810095024A CN 101267331 A CN101267331 A CN 101267331A
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Abstract
The embodiment of the invention discloses a method and a device for searching for a multicast forwarding table, at least two keywords are mainly obtained from the received data message frame head; the keywords at least comprise a first level keyword and a second level keyword; according to the first level keyword, an address index of the second level multicast forwarding table corresponding to the first level keyword is obtained by searching in the first level multicast forwarding table; in terms of the address index of the second level multicast forwarding table and the second level keyword, the list item contents corresponding to the address index of the second level multicast forwarding table and the second level keyword are obtained by searching in the second level multicast forwarding table. It can save the storage space, reduce the search time and include better universality and expandability by using the technical proposal above.
Description
Technical field
The present invention relates to communication technical field, relate in particular to a kind of multicast forward table lookup method and device.
Background technology
Along with Internet protocol (IP, International Protocol) networks development, network application is also more and more abundanter.Class new applications such as video conferencing, electronic whiteboard occurred, these are used to use with Traditional IP and compare, and data volume is bigger, and each sends point and have a plurality of acceptance points, but not every network node.Under such demand background, produced the ip multicast technology, ip multicast, be also referred to as multi-address broadcast or multicast, be that a kind of one or more main frame of permission is as multicast source, send once, transmission control protocol (TCP, Transfer Control the Protocol)/IP network technology of single packet simultaneously to multiple host.The function that multicast need be finished is to allow transmitting terminal send data to a group.Compare with broadcast mode with repetition point-to-point communication mode, in multicast application, use single data flow to substitute a plurality of data flow, can realize a little avoiding unnecessary bandwidth and processing time waste simultaneously, thereby on limited Internet resources, satisfy the multicast application demand to the communication of multiple spot.
Below, the concrete processing procedure of multicast in switching equipment is described by the application in Ethernet:
In ethernet switching device, generally comprise a plurality of quick retransmission units (EFU, ExpressForwarding Unit) and traffic management device (TM, Traffic Manager), EFU is made up of EFU upstream cell and EFU downstream units.EFU and device port are mutual, are responsible for forwarding behavior and carry out; TM is cut apart the up-downgoing data of forwarding, receives flow from EFU, and the scheduling of responsible flow is duplicated and flow is sent it back EFU.For for simplicity, comprise 1 EFU and 1 flow processing procedure that TM comes the brief description network switching equipment with the network switching equipment, with reference to Fig. 1, be network switching equipment structural representation in the prior art, P1, P2, P3 are the equipment end slogan:
Below in conjunction with Fig. 1, divide the concise and to the point multicast processing procedure of setting forth in the switching equipment of three steps:
The first step, retransmission unit (EFU, Express Forwarding Unit) upstream cell is handled fast: EFU and device port are mutual, the flow of coming on the receiving lines.Suppose that at first P2, P3 port side user have added some multicast group G.After multicast message enters from the P1 port, can remove to search multicast media interviews control (MAC, Media Access Control) table, according to the purpose mac address search of data message behind multicast MAC table, return a multicast sign (MID, Multicast Identification), this MID is encapsulated in frame head and sends to TM;
In second step, TM handles: TM preserves the outbound port number of a MID and the chained list of number of copies in advance, manages the list item of TM chip, and it has the function that message is duplicated.After EFU will encapsulate message behind the MID and send to TM, TM can obtain the number of copies of corresponding output port number and this port according to this MID, duplicate many parts of messages to this port then and send to the descending of EFU successively, the corresponding number of copies sequence number of the data message after each part duplicates;
In the 3rd step, the EFU downstream units is handled: TM is according to MID corresponding port number and number of copies, is sent back to EFU again after message is duplicated; Guild is according to MID under the EFU, the corresponding end slogan and duplicate after the number of copies sequence number of each data message correspondence remove to search downlink table (ELB, EgressLink Block), thereby obtain this message forwarding information.
Usually, suppose that switching equipment can support 8K MID, 64 ports, the corresponding port numbers of each port, the maximum replication capacity of each port is 128 parts, then descending at EFU, remove to search the ELB table according to MID, port numbers and number of copies sequence number, then the specification of this ELB is exactly: 8K*64*128=64M bar list item.
Because ELB is relatively large, reach 10,000,000 grades capacity, place it in ternary memory (TCAM, Ternary Content Addressable Memory) can't meet the demands in, can only be placed on static random access memory (SRAM than large storage capacity, Synchronous Random Access Memory) and in the dynamic random access memory (DRAM, Dynamic Content Addressable Memory).Taking cost into account, generally this table is placed among the less expensive DRAM.With reference to Fig. 2, be ELB schematic diagram in the prior art, the keyword of searching this ELB is made of MID, port numbers, number of copies sequence number.
In research and practice process to prior art, the inventor finds in the prior art, and ELB is left among the DRAM as linear list, needs very big memory space, and cost is higher; Simultaneously,, adopt above-mentioned linear search technique consuming time bigger, and be difficult to safeguard carrying out the big specification list item of multicast when searching.And even MID or PORT have an increase, the space of ELB then can be 128 multiple growth, therefore, but versatility and poor expandability.And if with ELB as non-linear table, by hash algorithm and adopt the method for binary tree to search, then can increase the microcode operation complexity greatly, especially for instruction space network processing unit (NP at full stretch, Network Processor), be difficult to realize.
Summary of the invention
The embodiment of the invention provides a kind of multicast forward table lookup method and device, can conserve storage, and reduce and search the time, but improve extensibility and versatility.
For solving the problems of the technologies described above, multicast forward table lookup method provided by the present invention and device embodiment are achieved through the following technical solutions:
The embodiment of the invention provides a kind of multicast forward table lookup method, and this method comprises:
Obtain both keyword at least from the data message frame head that is received, described keyword comprises first order keyword and second level keyword at least;
According to described first order keyword, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index and the corresponding contents in table of described second level keyword that obtain with described second level multicast forward table.
The embodiment of the invention provides a kind of multicast forward table to search device, and this device comprises:
The keyword acquiring unit is used for obtaining both keyword at least from the data message frame head that is received, and described keyword comprises first order keyword and second level keyword at least;
First searches the unit, is used for searching first order multicast forward table according to described first order keyword, searches the allocation index that obtains with the corresponding second level of described first order keyword multicast forward table from described first order multicast forward table;
Second searches the unit, be used for allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index of the described second level of acquisition multicast forward table and the contents in table of second level keyword correspondence.
The embodiment of the invention also provides a kind of switching equipment, and this switching equipment comprises: TM unit and EFU downstream units, and described EFU downstream units and TM unit carry out data interaction, and described EFU downstream units comprises:
The keyword acquiring unit is used for obtaining both keyword at least from the data message frame head that is received, and described keyword comprises first order keyword and second level keyword at least;
First searches the unit, is used for according to described first order keyword search first order multicast forward table, searches the allocation index that obtains the second level multicast forward table corresponding with described first order keyword from described first order multicast forward table;
Second searches the unit, be used for allocation index and the keyword search second level, described second level multicast forward table, from the multicast forward table of the described second level, search the allocation index and the pairing contents in table of second level keyword that obtain described second level multicast forward table according to described second level multicast forward table.
The technical scheme of the embodiment of the invention is by obtaining both keyword at least, and described keyword comprises first order keyword and second level keyword at least, according to described first order keyword search first order multicast forward table, obtain the allocation index of second level multicast forward table, allocation index and described second level keyword according to the second level multicast forward table that obtains, search second level multicast forward table, obtain the allocation index of described second level multicast forward table and the contents in table of second level keyword correspondence; Because the multicast forward table in the technique scheme is searched by the multicast forward table classification is realized, the keyword branch searched is represented wherein mapping relations at least two multicast forward tables and by allocation index, multicast forward table for big specification, after representing by hierarchical table, can remove the number of the keyword in the multicast forward tables at different levels of first order multicast forwarding off-balancesheet according to the service needed flexible allocation, the number that does not need all keywords is all according to the maximum specification setting, therefore can conserve storage, reduce cost; Simultaneously, because the number of keyword correspondence in can the flexible configuration multicast forward table, the specification of multicast forward table reduces greatly, therefore can greatly save the time of searching, and do not need very big microcode complicated operation degree, can save the instruction space, be suitable for the nervous network processing unit of the instruction space; And,, therefore be easy to safeguard, and the number of distributing the keyword of being supported in the multicast forward tables at different levels according to actual needs has better generality and extensibility because each multicast forward table is all less.
Description of drawings
Fig. 1 is a network switching equipment structural representation in the prior art;
Fig. 2 is an ELB schematic diagram in the prior art;
Fig. 3 is a multicast forward table lookup method flow chart in the embodiment of the invention;
Fig. 4 a is that first order multicast forward table is searched schematic diagram in the embodiment of the invention;
Fig. 4 b is that second level multicast forward table is searched schematic diagram in the embodiment of the invention;
Fig. 5 searches device embodiment one structural representation for multicast forward table in the embodiment of the invention;
Fig. 6 searches device embodiment two structural representations for multicast forward table in the embodiment of the invention;
Fig. 7 is switching equipment embodiment one structural representation in the embodiment of the invention;
Fig. 8 is switching equipment embodiment two structural representations in the embodiment of the invention.
Embodiment
The embodiment of the invention provides a kind of multicast forward table lookup method and device, and in this multicast forward table lookup method, by obtaining both keyword at least, described keyword comprises first order keyword and second level keyword at least; According to the first order keyword that obtains, search first order multicast forward table, from first order multicast forward table, search acquisition and first order keyword corresponding address index; According to allocation index that is obtained and the second level keyword that obtained, search second level multicast forward table then, from the multicast forward table of the second level, search and obtain and described allocation index and the corresponding contents in table of second level keyword; When described contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.This multicast forward table lookup method can conserve storage, reduces and searches the time, but improve extensibility and versatility.
For the purpose, technical scheme and the advantage that make the embodiment of the invention more cheer and bright, below with reference to accompanying drawing, be applied in multicast forward table in the switching network equipment search and forwarding is that example is elaborated:
With reference to Fig. 3, be multicast forward table lookup method embodiment flow chart in the embodiment of the invention, below be elaborated by concrete steps:
When being applied in switching network equipment, after multicast data message enters the EFU upstream cell, can show to obtain the MID corresponding by searching multicast MAC with the target MAC (Media Access Control) address of described multicast data message, then this MID is encapsulated in and sends to TM in the frame head, TM gets access to be encapsulated in after corresponding port number and the number of copies sequence number according to this MID and sends to the EFU downstream units in the frame head.The EFU downstream units is resolved this frame head and is obtained MID, port numbers and number of copies sequence number.
The information of certain byte that frame head normally adds in the front of data message after data message enters switching equipment, the information of being added is the privately owned information of switching equipment, in order to sign message some information when handling, as the outbound port of this message number, message is that clean culture still is privately owned signs such as multicast, and is only effectively inner at switching equipment.When switching equipment sent, this information was deleted in the processed back that finishes of message.
MID and port numbers that step 32, basis are obtained are searched first order multicast forward table, obtain described MID and port numbers corresponding address index;
With the MID that obtains and port numbers as first order keyword, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains this MID and the pairing second level of port numbers multicast forward table, with reference to Fig. 4 a, for first order multicast forward table in the embodiment of the invention is searched schematic diagram, according to MID and port numbers PORT, find corresponding down link table offset address ELB OffsetAddress;
Allocation index that step 33, basis are obtained and the number of copies sequence number of having obtained are searched second level multicast forward table, search from the multicast forward table of the second level and obtain this allocation index and the pairing contents in table of number of copies sequence number.
Allocation index that utilization is obtained from first order multicast forward table and the number of copies sequence number of obtaining are before searched second level multicast forward table, with reference to Fig. 4 b, for second level multicast forward table in the embodiment of the invention is searched schematic diagram, the number of copies sequence number is as second level keyword, according to ELB Offset Address and number of copies sequence number, can find corresponding ELB data, get access to the contents processing of message.
This list item comprises this message some forwarding informations when this switching equipment sends, be common two layers of forwarding or go into virtual private networks service (VPLS as this message, Virtual Private LAN Service) and from this equipment is gone out time encapsulation is virtual network sign vlanID or link translation-protocol (LSP, Link Switching Protocol) sign etc.
Suppose that the MID number has 8K, still support 64 ports, the specification of first order multicast forward table is so: 8K*64=512K, and for second level multicast forward table, the specification of ELB table can be set according to the equipment actual demand, for example in actual environment, do not need all ports all to duplicate 128 parts, then can dispose second level multicast forward table, realize the dynamic assignment of second level multicast forward table by the mapping relations and the number of copies sequence number of list item in ELB Offset Address value in the first order multicast forward table and the second level multicast forward table.For example, equipment is supported 8K MID, 64 ports, so the specification of first order multicast forward table is exactly a 8K*64=512K bar list item, be that multicast sign and port numbers corresponding relation have the 512K kind, and the 72K that hypothesis needs only among the support 512K in the actual scene is just enough, suppose in scene, only to have the requirement of part port to duplicate 128 parts, the maximum support of other ports duplicated 8 parts, the greatest requirements of wherein duplicating 128 parts is 8K, and the greatest requirements of duplicating 8 parts is 64K, and the specification of ELB table is so: 8K*128+64*8=1536K bar list item, compare with the 64M of single linear ELB table, reduced nearly 40 times memory space from capacity.As seen, for a switching equipment, in actual applications, though it supports 8K multicast sign, but may and not require that all corresponding 64 ports of each multicast sign and each port all duplicate 128 parts, therefore, adopt the classification multicast forward table to search, can conserve storage, reduce and search time loss.
As seen, by MID and the port numbers of obtaining, search first order multicast forward table, obtain this MID and port numbers corresponding address index, and according to allocation index that obtains and the number of copies sequence number obtained, search second level multicast forward table, obtain this multicast sign, port numbers and the pairing contents in table of number of copies sequence number, and can handle the data message according to contents in table.This multicast forward table lookup method is realized by the two-stage table, because keyword branch that will be searched is represented wherein mapping relations in two tables and by allocation index, multicast forward table for big specification, after representing by the two-stage table, the number of can flexible allocation removing corresponding keyword in the multicast forward tables at different levels of first order multicast forwarding off-balancesheet, therefore, the multicast forward tables at different levels that remove first order multicast forwarding off-balancesheet do not need to represent with maximum specification, make the multicast forward table overall specifications reduce greatly, therefore can conserve storage, reduce cost; Simultaneously,, therefore can greatly save the time of searching, and not need very big microcode complicated operation degree, can save the instruction space, be suitable for instruction space network processing unit more in short supply because the specification of multicast forward table reduces greatly; And the number of copies supported of port number of being supported in the flexible allocation first order multicast forward table and second level multicast forward table has better generality and extensibility according to actual needs.
Be understandable that, situation for both keyword, this both keyword will be divided into two-stage, respectively as first order keyword and second level keyword, supposing that this both keyword is A, B, then A can be defined as first order keyword, is second level keyword and B decides doctrine, also B can be defined as first order keyword, and A is defined as second level keyword.According to described first order keyword, search first order multicast forward table, obtain the allocation index of second level multicast forward table; Then according to the allocation index and the second level keyword that from first order multicast forward table, obtain, search second level multicast forward table, from the multicast forward table of the second level, search the allocation index that obtains described second level multicast forward table and the contents in table of second level keyword correspondence.The number of the second level keyword of each allocation index correspondence in the multicast forward table of the second level can be set as required, therefore can reduce the specification of multicast forward table, conserve storage and searching the time, and improve the versatility and the extensibility of described multicast forward table.
Equally, situation for three above keywords, also described keyword can be divided into two-stage, suppose that described keyword comprises A1, B1, C1, D1, then can according to actual needs these four keywords be divided into two-stage, for example can be with any or two among A1 or A1 and B1, C1, the D1 as first order keyword, remaining keyword is then as second level keyword; Certainly, also can select any or two among A1 or A1 and B1, C1, the D1 as second level keyword, remaining keyword is then as first order keyword.According to described first order keyword, search first order multicast forward table, obtain the allocation index of second level multicast forward table; Then according to the allocation index and the second level keyword of the described second level multicast forward table that from first order multicast forward table, obtains, search second level multicast forward table, from the multicast forward table of the second level, search the allocation index that obtains described second level multicast forward table and the contents in table of second level keyword correspondence, the number of the second level keyword of each allocation index correspondence in the multicast forward table of the second level can be set as required, therefore can reduce the specification of multicast forward table, conserve storage and searching the time, and improve the versatility and the extensibility of described multicast forward table.
Be understandable that, when the keyword number is more, also can search according to above-mentioned multicast forward table lookup method, at first obtain keyword, these keywords are divided at least three grades, for example, when three grades of multicast forward tables, the keyword of every grade of multicast forward table correspondence can be used first order keyword successively, second level keyword, third level keyword is represented, when the level Four multicast forward table, the keyword of every grade of multicast forward table correspondence can be used first order keyword successively, second level keyword, third level keyword, fourth stage keyword, corresponding, multicast forward table can be described as first order multicast forward table, second level multicast forward table, third level multicast forward table, fourth stage multicast forward table, the rest may be inferred.
For example,, can search first order multicast forward table, from first order multicast forward table, search the allocation index that obtains second level multicast forward table according to the first order keyword that obtains for the situation of three grades of multicast forward tables; According to the allocation index and the second level keyword of described second level multicast forward table, search second level multicast forward table then, from the multicast forward table of the described second level, search the allocation index that obtains third level multicast forward table; According to the allocation index and the third level keyword of described third level multicast forward table, search third level multicast forward table, from described third level multicast forward table, to search and obtain corresponding contents in table, described contents in table is a multicast forwarding information.Situation for the level Four multicast forward table, then searching what obtain from above-mentioned third level multicast forward table is not multicast forwarding information, but the allocation index of fourth stage multicast forward table, allocation index and fourth stage keyword according to described fourth stage multicast forward table, continue to search fourth stage multicast forward table, from described fourth stage multicast forward table, search corresponding contents in table, i.e. the multicast forwarding information obtained at last.
Therefore, multicast forward table for big specifications such as ELB, can be divided into the above multicast forward table of two-stage or two-stage represents, first order multicast forward table is deposited the allocation index of second level multicast forward table, and the like, by searching the allocation index that the upper level multicast forward table obtains multicast forward table at the corresponding levels, according to allocation index that obtains from the upper level multicast forward table and keyword at the corresponding levels, search multicast forward table at the corresponding levels, thereby obtain at the corresponding levels concrete contents in table, when the contents in table of searching acquisition from multicast forward table at the corresponding levels is the allocation index of the next stage multicast forward table of multicast forward table at the corresponding levels, rather than during multicast forwarding information, then can be according to the above-mentioned next stage multicast forward table of searching the mode of multicast forward table at the corresponding levels from multicast forward table at the corresponding levels, search the multicast forward tables at different levels behind the multicast forward table at the corresponding levels step by step downwards, until searching the multicast forwarding information that obtains.Owing to can flexible allocation remove the number of corresponding stage keyword in the multicast forward tables at different levels of first order multicast forwarding off-balancesheet, determine the specification of multicast forward tables at different levels, make the total specification of multicast forward table reduce greatly, and then can conserve storage and search the time, and improve the versatility and the extensibility of described multicast forward table.
More than the multicast forward table lookup method that the embodiment of the invention adopted is described in detail, for those skilled in the art being understood better and realize the embodiment of the invention, below the device that is adopted in the said method carried out correspondence describe.
With reference to Fig. 5, search device embodiment one structural representation for multicast forward table in the embodiment of the invention, this device comprises:
Keyword acquiring unit 51 is used for obtaining both keyword at least from the data message frame head that is received, and described keyword comprises first order keyword and second level keyword at least;
First searches unit 52, be used for the first order keyword that obtains according to keyword acquiring unit 51, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Second searches unit 53, be used for searching allocation index and the second level keyword that unit 52 obtains according to first, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index that obtains described second level multicast forward table and the contents in table of second level keyword correspondence.
In addition, the multicast forward table of the embodiment of the invention is searched device, can also comprise that the 3rd searches the unit, be used for when above-mentioned contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
The first order keyword that described keyword acquiring unit 51 is obtained can be MID, port numbers, and second level keyword can be the number of copies sequence number.
This multicast forward table is searched device because can be according to the first order keyword search first order multicast forward table that obtains, obtain the allocation index of second level multicast forward table, and according to the allocation index of the second level multicast forward table that obtains and the second level keyword that has obtained, search second level multicast forward table, obtain the allocation index of described second level multicast forward table and the contents in table of second level keyword correspondence.Owing to search by classification, can be according to the number of corresponding keyword in the multicast forward table of the service needed flexible allocation second level, as long as satisfy service needed, the number that does not need each keyword is all according to the maximum specification setting, therefore can conserve storage, reduce cost; Simultaneously,, can greatly save the time of searching, and not need very big microcode complicated operation degree, can save the instruction space, be suitable for the nervous network processing unit of the instruction space because the specification of multicast forward table reduces greatly; And,, therefore be easy to safeguard, and the number of distributing applied keyword in the multicast forward tables at different levels according to actual needs has better generality and extensibility because each multicast forward table is all less.
With reference to Fig. 6, search device embodiment two structural representations for multicast forward table in the embodiment of the invention, this device comprises:
The 3rd searches unit 64, be used for searching the allocation index of the third level multicast forward table that unit 63 obtains and the third level keyword that keyword acquiring unit 61 obtains according to second, search third level multicast forward table, search the allocation index and the corresponding contents in table of third level keyword that obtain with described third level multicast forward table from described third level multicast forward table, described contents in table is a multicast forwarding information.
As can be seen, search in the device at this multicast forward table, according to different keywords the multicast forward table classification is represented, for the multicast forward tables at different levels except that first order multicast forward table, the number of keywords at different levels can be set as required, do not need all keywords all according to the maximum number setting, therefore, can reduce the specification of multicast forward table greatly, and then can conserve storage, reduce cost; Simultaneously,, can greatly save the time of searching, and not need very big microcode complicated operation degree, can save the instruction space, be suitable for the nervous network processing unit of the instruction space because the specification of multicast forward table reduces greatly; And,, therefore be easy to safeguard, and the number of distributing the keyword of being supported in the multicast forward tables at different levels according to actual needs has better generality and extensibility because each multicast forward table is all less.
With reference to Fig. 7, be switching equipment embodiment one structural representation in the embodiment of the invention, this switching equipment comprises: TM unit 71 and EFU downstream units 72, EFU downstream units 72 and TM unit 71 carry out data interaction, and wherein, EFU downstream units 72 comprises:
Generally, by header parsing can obtain three keywords such as MID, port numbers and number of copies sequence number to the data message frame.In embodiments of the present invention, described MID and port numbers are first order keyword, and described number of copies sequence number is a second level keyword.
As seen, the first order keyword of this switching equipment by obtaining, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains second level multicast forward table, and according to allocation index that obtains and second level keyword, search second level multicast forward table, from the multicast forward table of the described second level, search and obtain corresponding contents in table, be used for the deal with data message forwarding.Hence one can see that, the method that the switching equipment of the embodiment of the invention is searched multicast forwarding information realizes by the classification multicast forward table, because keyword branch that will be searched is represented wherein mapping relations in the two-stage multicast forward table and by allocation index, multicast forward table for big specification, after representing by hierarchical table, because the number of corresponding keyword in can flexible allocation second level multicast forward table, make the multicast forwarding table size reduce greatly, therefore can conserve storage, reduce cost; Simultaneously,, therefore can greatly save the time of searching, and not need very big microcode complicated operation degree, can save the instruction space, be suitable for instruction space network processing unit more in short supply because the specification of multicast forward table reduces greatly; And, because each multicast forward table is all less, be easy to therefore safeguard that multicast sign number and the port number that can also expand in the multicast forward table according to actual needs to be supported have better generality and extensibility.
Below a kind of switching equipment of supporting the multicast forward table more than three grades and three grades to search is described in detail by specific embodiment:
With reference to Fig. 8, be switching equipment embodiment two structural representations in the embodiment of the invention, this switching equipment comprises TM unit 81 and EFU downstream units 82, and described EFU downstream units 82 is carried out data interaction with TM unit 81, it is characterized in that described EFU downstream units 82 comprises:
The 3rd searches unit 824, be used for searching the allocation index of the third level multicast forward table that unit 823 obtains and the third level keyword that keyword acquiring unit 821 obtains according to second, search third level multicast forward table, search the allocation index and the corresponding contents in table of third level keyword that obtain with described third level multicast forward table from described third level multicast forward table, described contents in table is a multicast forwarding information.
As from the foregoing, search situation for the multicast forward table more than three grades, the 3rd of embodiment of the invention switching equipment is searched the unit, be used for when second searches the unit and search the contents in table of acquisition and be the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
One of ordinary skill in the art will appreciate that all or part of step that realizes in the foregoing description method is to instruct relevant hardware to finish by program, described program can be stored in a kind of computer-readable recording medium, this program comprises the steps: when carrying out
Obtain both keyword at least from the data message frame head from TM, described keyword comprises first order keyword and second level keyword at least;
According to described first order keyword, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Allocation index and described second level keyword according to institute's second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index that obtains described second level multicast forward table and the contents in table of described second level keyword correspondence;
When described contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
The above-mentioned storage medium of mentioning can be a read-only memory, disk or CD etc.
One of ordinary skill in the art will appreciate that all or part of step that realizes in the foregoing description method is to instruct relevant hardware to finish by program, described program can be stored in a kind of computer-readable recording medium, this program comprises the steps: when carrying out
Obtain at least three keywords from the data message frame head from TM, described keyword comprises first order keyword, second level keyword and third level keyword at least;
According to the first order keyword that obtains, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Allocation index and second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index that obtains the third level multicast forward table corresponding with the allocation index of described second level multicast forward table and second level keyword;
Allocation index and third level keyword according to the third level multicast forward table that is obtained, search third level multicast forward table, search the allocation index and the corresponding contents in table of third level keyword that obtain with described third level multicast forward table from described third level multicast forward table, described contents in table is a multicast forwarding information.
The above-mentioned storage medium of mentioning can be a read-only memory, disk or CD etc.
More than a kind of multicast forward table lookup method provided by the present invention and device are described in detail, for one of ordinary skill in the art, thought according to the embodiment of the invention, part in specific embodiments and applications all can change, in sum, this description should not be construed as limitation of the present invention.
Claims (10)
1, a kind of multicast forward table lookup method is characterized in that, comprising:
Obtain both keyword at least from the data message frame head that is received, described keyword comprises first order keyword and second level keyword at least;
According to described first order keyword, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index and the corresponding contents in table of described second level keyword that obtain with described second level multicast forward table.
2, multicast forward table lookup method as claimed in claim 1, it is characterized in that, described method also comprises: when described contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
3, multicast forward table lookup method as claimed in claim 2 is characterized in that, when described keyword comprised first order keyword, second level keyword and third level keyword at least, described multicast forward table lookup method was specially:
Always in the data message frame head of flowtube reason device TM, obtain described first order keyword, second level keyword and third level keyword;
According to described first order keyword, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described first order keyword;
Allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index that obtains the third level multicast forward table corresponding with the allocation index of described second level multicast forward table and described second level keyword;
Allocation index and described third level keyword according to described third level multicast forward table, search third level multicast forward table, from described third level multicast forward table, search the allocation index and the corresponding described multicast forwarding information of described third level keyword that obtain with described third level multicast forward table.
4, multicast forward table lookup method as claimed in claim 1 or 2 is characterized in that, when described keyword comprised multicast sign, port numbers and number of copies sequence number, described multicast forward table lookup method was specially:
Obtain described multicast sign, described port numbers and described number of copies sequence number from the data message frame head from TM, described multicast sign and port numbers are described first order keyword, and described number of copies sequence number is a described second level keyword;
According to described multicast sign and port numbers, search first order multicast forward table, from described first order multicast forward table, search the allocation index that obtains the second level multicast forward table corresponding with described multicast sign and port numbers;
According to the allocation index and the described number of copies sequence number of described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the multicast forwarding information corresponding that obtains with described number of copies sequence number.
5, a kind of multicast forward table is searched device, it is characterized in that, comprising:
The keyword acquiring unit is used for obtaining both keyword at least from the data message frame head that is received, and described keyword comprises first order keyword and second level keyword at least;
First searches the unit, is used for searching first order multicast forward table according to described first order keyword, searches the allocation index that obtains the second level multicast forward table corresponding with described first order keyword from described first order multicast forward table;
Second searches the unit, be used for allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index of the described second level of acquisition multicast forward table and the contents in table of second level keyword correspondence.
6, multicast forward table as claimed in claim 5 is searched device, it is characterized in that, described device comprises that also the 3rd searches the unit, be used for when described contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
7, search device as claim 5 or 6 described multicast forward tables, it is characterized in that, described keyword acquiring unit is used for obtaining three described keywords from the data message frame head that is received, described three keywords are respectively multicast sign, port numbers and number of copies sequence number, wherein said multicast sign and port numbers are described first order keyword, and described number of copies sequence number is a described second level keyword; Described second searches the unit, be used for allocation index and described second level keyword, from the multicast forward table of the described second level, search the allocation index of the described second level of acquisition multicast forward table and the multicast forwarding information of second level keyword correspondence according to described second level multicast forward table.
8, a kind of switching equipment comprises traffic management device TM unit, it is characterized in that, also comprises the quick retransmission unit EFU downstream units of carrying out data interaction with described TM unit, and described EFU downstream units comprises:
The keyword acquiring unit is used for obtaining both keyword at least from the data message frame head that is received, and described keyword comprises first order keyword and second level keyword at least;
First searches the unit, is used for searching first order multicast forward table according to described first order keyword, searches the allocation index that obtains the second level multicast forward table corresponding with described first order keyword from described first order multicast forward table;
Second searches the unit, be used for allocation index and described second level keyword according to described second level multicast forward table, search second level multicast forward table, from the multicast forward table of the described second level, search the allocation index of the described second level of acquisition multicast forward table and the contents in table of second level keyword correspondence.
9, switching equipment as claimed in claim 8, it is characterized in that, described EFU downstream units comprises that also the 3rd searches the unit, be used for when described contents in table is the allocation index of next stage multicast forward table of described second level multicast forward table, according to the above-mentioned next stage multicast forward table of searching the mode of described second level multicast forward table from described second level multicast forward table, search the multicast forward tables at different levels behind the multicast forward table of the described second level step by step downwards, until searching the multicast forwarding information that obtains.
10, switching equipment as claimed in claim 8 or 9, it is characterized in that, described keyword acquiring unit is used for obtaining three described keywords from the data message frame head that is received, described three keywords are respectively multicast sign, port numbers and number of copies sequence number, wherein said multicast sign and port numbers are described first order keyword, and described number of copies sequence number is a described second level keyword; Described second searches the unit, be used for allocation index and described second level keyword, from the multicast forward table of the described second level, search the allocation index of the described second level of acquisition multicast forward table and the multicast forwarding information of second level keyword correspondence according to described second level multicast forward table.
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