A method for quickly carrying out equivalence partition in packet classification

Abstract

The disclosed fast equipotent division method in ACL comprises: initiating all structures in matching range as a set with only one line segment, and setting the equivalent ID value of the line segment as the initial value; when adding rule, from the initial line segment of every set, comparing in turn the cover range and line range, and recording or re-allocating equivalent ID value according to comparison result; then, re-allocating the initial values or equivalent ID value with line segment not complete recorded, storing ID values covered by rule, and setting into one on relative position of equivalent bit image. This invention can increase in-effect speed for rule.

Description

technical field The invention relates to a method for classifying packets by a router, in particular to a method for quickly dividing equivalence classes in flow classification. Background technique In common routers, traffic classification is an important basic function. The setting of traffic classification can be done through ACL (Access Control List). ACL provides a newer and more flexible management method for network administrators. ACL is widely used in packet filtering, NAT (Network Address Translation), Qos (Quality of Service), policy routing, uRPF (Unicast Reverse Path Forwarding) and other applications. Among the ACL matching algorithms implemented by software, the RFC (Recursive Flow Classification) algorithm is widely used and has better performance. As shown in Figure 1, the RFC algorithm constructs multiple equivalent Class and multi-level index table, the packet matches the index table step by step, and obtains the classID (equivalence class number) to w...

AI Technical Summary

Problems solved by technology

Using this method is more efficient for the process of searching and positioning, but when dividing equivalence classes, there is a problem of low efficiency. All rules must be collected together, and CLASS BITMAP (CBM) (equivalence class bit Figure) to divide the equivalence classes

If the number of rules is huge, the number of BITMAP (bitmap) digits required will also increase accordingly, and a large number of logical "and" and "comparison" work will be required, and the memory will be read and written multiple times, and each time an ACL rule is added / deleted, Both need to be recalculated, which is not suitable for practical applications, which require the rapid generation of equivalence classes to make the rules take effect quickly

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