Method of three-layer conversion information down transmitting hardware LPM table

Abstract

This invention discloses a method for delivering a three-layer forward information to hardware LPM list, among which, the top layer FIB is delivered to said hardware LPM list and tuple S and F of IP prefix value are designed for storing FIB successful or failed delivery. When FIB is delivered, tuple F is searched first to see if there is item matched to said IP prefix, if so, the route item list is inserted into tuple F, otherwise, the IP prefix value is inserted into LPM list. If the insertion is done, it is stored in tuple S, if its failed, it's inserted into tuple F and all short prefix lists of the IP prefix values in LPM are cancelled. After that, other prefix values in F are tried to insert into LPM, if it's done, all short prefixes related to IP are inserted into LPM and S.

Description

Technical field:

[0001] The invention relates to a method for issuing a hardware LPM table with three-layer forwarding information. Background technique:

[0002] Generally, the LPM (Longest-Prefix-Match, longest prefix match) table space in the forwarding chip on the interface board of the three-layer switch is very limited. When the upper layer FIB (Forwarding Information Base, routing and forwarding table) is sent to this hardware table, it often happens that the table is full and the insertion fails. In addition, the current routing and forwarding matching algorithm is the longest match. If a long mask prefix is ​​not inserted successfully, all corresponding short mask prefixes must be deleted from the hardware table. Although the deletion of these short masks frees up space, the The insertion of this long mask does not bring any benefit. At this time, we can only try to insert other network prefixes. In this way, the hardware table must be frequently accessed, thereby...

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