Method and device for managing list item of content addressable memory CAM

A technology for addressing memory and entry management, which is applied in the computer field and can solve problems such as complex software implementation, low efficiency, and complex implementation of CAM entry management schemes, and achieve the effects of improving efficiency and reducing CPU occupation time

Inactive Publication Date: 2010-01-06
NEW H3C TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0034] 1. The software implementation is complex, and the maintenance and update of CAM entries need to implement functions such as search, move, and defragmentation similar to memory management
[0035] 2. The up

Method used

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  • Method and device for managing list item of content addressable memory CAM
  • Method and device for managing list item of content addressable memory CAM
  • Method and device for managing list item of content addressable memory CAM

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Embodiment 1

[0077]In the prior art, when CAM is in Binary Encoded output mode or Single-match Un-encoded output mode, when there are multiple matches, CAM needs to select from these matching entries One as the last lookup result. In order to meet the needs of practical applications, such as the longest prefix match of routing and the first hit match of ACL, CAM stipulates that the highest or lowest matching address should be returned when there are multiple matches, and it is generally stipulated that the table with the lowest address should be selected from all matching entries in CAM item as the final result. Therefore, when storing entry contents in the CAM, they need to be stored in a certain order, which brings about complex management of CAM entries.

[0078] Figure 5 is a schematic diagram of an existing CAM system. like Figure 5 As shown, when CAM matching is performed according to the search data, two table entries of stored data 2 and stored data w-2 are hit, wherein the m...

Embodiment 2

[0084] In this embodiment 2, for the CAM of the multi-match unencoded (Multi-Match Un-encoded) output mode, its output data width is equal to the TCAM depth, and each entry corresponds to a CAM output bit, then in this embodiment is A corresponding field is added to each CAM output bit, and the corresponding field stores priority information of an entry corresponding to the corresponding CAM output bit. When a single matching result needs to be output, the priority information of the matching entry is compared according to the CAM output data, or the priority information of the matching entry and the matching address information are compared, and finally an output result is selected.

[0085] Figure 8 It is a schematic diagram of the CAM entry management method in Embodiment 2 of the present invention. like Figure 8 As shown, in the CAM system of the Multi-Match Un-encoded output mode, the depth of the TCAM entry is 32, and the width of the CAM output data is also 32 bits,...

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Abstract

The invention discloses a method and a device for managing list items of a content addressable memory CAM. The method comprises the following steps: storing a priority level message which corresponds to each list item of the content addressable memory CAM; and when a plurality of matched list items are obtained by searching data to match the list items of the content addressable memory CAM, selecting one matched list item according to the priority level message which corresponds to each matched list item or the priority level message or a matched address message which corresponds to each matched list item. The invention is easy to realize and has high efficiency.

Description

technical field [0001] The invention relates to the field of computer technology, in particular to a method and device for managing CAM entries of a content addressable memory. Background technique [0002] Content addressable memory (CAM, Content Addressable memory) is a special computer memory for high-speed search. It is a hardware search engine provided for searching time-sensitive applications. It has a faster search speed than the search method using algorithms. . [0003] There are two basic forms of CAM: dual content addressable memory (BCAM, Binary CAM) and triple content addressable memory (TCAM, Ternary CAM). BCAM is a simple CAM that supports storage and search of two forbidden bits (0 or 1). TCAM supports the third matching state "don't care", represented by "X", which is used to provide flexible search. For example, TCAM stores an entry as "10XX0", and this entry will match any one of the four search words "10000", "10010", "10100", and "10110". Compared wi...

Claims

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Application Information

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IPC IPC(8): G06F17/30H04L12/56
Inventor 赵里遥祁正林
Owner NEW H3C TECH CO LTD
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