Method and device for matching longest prefix based on tree form data structure

Abstract

The invention discloses a method and a device for matching a longest prefix. The method comprises the following steps: A, reading a search node; B, determining whether the offset domain of the read search node indicates that an upper node has the matched prefix or not, adding the offset domain of the search node to a pointer pointing to a leaf node array in the upper node if the upper node has the matched prefix, updating the current best matching pointer and executing the step C, and executing the step C if the upper node has no matched prefix; C, determining whether the search node has the leaf node or not while determining corresponding bit matching of branch indication domain and search key words of the search node; D, reading the internal bitmap of the search node while determining that the search node does not have the leaf node, computing the longest matching prefix existing in the search node according to the internal bitmap and the pointer pointing to the leaf node array in the search node, updating the current best matching pointer, and computing the address of the leaf node corresponding to the current best matching pointer. The method can improve the search speed.

Description

technical field [0001] The invention relates to the technical fields of communication and computer, in particular to a longest prefix matching method and device based on a tree data structure. Background technique [0002] When a router forwards an IP (Internet Protocol, Internet Protocol) message, it needs to query a routing table according to the destination address of the IP message. The routing table contains multiple routing prefixes, and each routing prefix is ​​usually represented by a string consisting of 0 / 1, for example: 01 * , the symbol at the end of the string " * " indicates that the following bits can take any value. Each routing prefix in the routing table corresponds to a next-hop information. The method adopts the longest prefix matching method. After finding the longest matching prefix, forward the IP message according to the next hop information corresponding to the prefix. The so-called longest prefix matching, for example: if there are two routes in t...

AI Technical Summary

Problems solved by technology

Trie is a tree structure used to save a large number of strings. It can use the common prefix of the string to save storage space. It has a fast update speed. The query performance is only related to the length of the address and not related to the number of prefixes. characteristics, so using Trie to achieve the longest prefix matching is a relatively common practice. For example, in the prior art, a method of searching and compressing multi-bit Tries is used to find the longest matching prefix. However, in the existing In the process of technical research and practice, the inventor found that if the matching method of compressing multi-bit Trie is used, if the step size is r, only r bits can be read at a time, and its query speed cannot meet the continuously increasing line rate requirements

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