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Flow stream searching method and device

A flow table and lookup table technology, applied in the field of data communication, can solve problems such as low search speed, affecting message forwarding performance, and insufficient access speed

Active Publication Date: 2009-09-23
NEW H3C TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the flow table is set in the external cache of the communication device processing chip, the access speed is not fast enough. Therefore, although the Hash conflict problem can be solved to a certain extent when the Hash bucket is deep, the packet forwarding will be seriously affected due to the low search speed. performance
[0007] Moreover, since the depth of each Hash bucket is the same, but the number of keywords corresponding to the same Index is different, some Hash buckets have a high utilization rate, for example figure 2 The Hash bucket at the address of Index1, and the utilization rate of some Hash buckets is very low, for example figure 2 Hash bucket at the address of Index3 in

Method used

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Experimental program
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Embodiment 2

[0067] Using the solution in Embodiment 1 may generate Hash conflicts. Suppose there is Hash(key3)=Index1, and the Hash bucket corresponding to Index1 is full and cannot accommodate the flow table entry of key3, then key3 is a conflicting key. One solution is to adjust the height of the hash bucket to accommodate more entries. However, when adjusting the height of the bucket, all hash buckets need to be adjusted in the same way, which will reduce the utilization of the hash bucket.

[0068] For this reason, Embodiment 2 of the present invention proposes a multi-level Hash flow table search method, which not only solves the above-mentioned possible Hash conflicts, but also effectively utilizes the remaining space of the Hash bucket. In this embodiment, for using the same Hash function to map more keywords to the same Index value, and the number of more keywords is greater than the depth of the Hash bucket, the more keywords are divided into at least two parts, different parts ...

Embodiment 3

[0095] Considering that there will still be a small probability of conflict events after the multi-level Hash in the above-mentioned embodiment two, such as Hash0(key8)=Index2, and Hash1(key8)=Index1, because the Hash buckets corresponding to Index1 and Index2 are full, thus A conflict arises. Although when the Hash depth is set to 8-16, the probability of conflicts is very small, but in order to further prevent conflicts, in the third embodiment of the present invention, a small standby Hash table is further set in the internal cache of the chip to solve this problem. conflict.

[0096] Figure 8 It is a schematic diagram of the standby Hash table in the third embodiment. For the key values ​​that still conflict after multi-level Hash, use the alternate Hash function (denoted as Hash'(x)) different from Hash0(x) and Hash1(x) to perform Hash operation on these key values, and the obtained Hash index is recorded as Index h’ ; Use the standby Hash table to record the Index o...

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Abstract

The invention discloses a flow stream searching method and a device. The method comprises the following steps of: setting a pre-searching table in internal cache of a chip, adopting the pre-searching table to record key words and corresponding relation of Index thereof, and calling part of fields which only record the key words as Flow value when recording. The recording position of the Flow value of the key words corresponds to the recording position of flow table entry corresponding to the key words in a Hash barrel. When searching the needed flow table entry for message, the invention can determine the recording position of the needed flow table entry in the external cache according to the position of Index obtained by carrying out Hash operation on the key words of the message and the Flow value matched with the key words of the message in the pre-search table entry, and obtain the needed flow table entry only by needing to access the external cache for once, thus achieving the purpose of fast search.

Description

technical field [0001] The invention relates to data communication technology, in particular to a method and device for improving the search performance of a flow table. Background technique [0002] In the field of data communication, it will involve the control of some second and third layer data forwarding. The data forwarding is to obtain the outgoing interface or some other attribute values ​​of the data by looking up the flow table. The lookup efficiency of the flow table affects the efficient transmission of data on the network. How to quickly achieve efficient lookup is a research focus for high-speed packet forwarding. [0003] figure 1 It is a flow chart of the flow table lookup and matching process in the prior art. Such as figure 1 As shown, when the message arrives, the keyword (key) used for the hash (Hash) operation is extracted from the message. The key is the message feature information, which can be determined in advance according to the actual network,...

Claims

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Application Information

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IPC IPC(8): H04L12/56G06F17/30H04L12/743
Inventor 王彬
Owner NEW H3C TECH CO LTD
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