发明授权
- 专利标题: Search engine for forwarding table content addressable memory
- 专利标题(中): 搜索引擎转发表内容可寻址内存
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申请号: US10329249申请日: 2002-12-23
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公开(公告)号: US07274693B1公开(公告)日: 2007-09-25
- 发明人: Raymond J. Kloth , Kevin D. Morishige , Venkateshwar Rao Pullela
- 申请人: Raymond J. Kloth , Kevin D. Morishige , Venkateshwar Rao Pullela
- 申请人地址: US CA San Jose
- 专利权人: Cisco Technology, Inc.
- 当前专利权人: Cisco Technology, Inc.
- 当前专利权人地址: US CA San Jose
- 代理机构: Thelen Reid Brown Raysman & Steiner LLP
- 主分类号: H04L12/56
- IPC分类号: H04L12/56
摘要:
A hardware search engine facility is provided to allow CPU search and update of a Forwarding Table CAM under the control of software running on the CPU. The hardware search engine provides one or more comparand-mask pairs which allow for a match, exclusion or magnitude comparison on specific entry values and/or the option to ignore or “don't care” certain bits of the entry. Control registers may be set in software to specify a start address and stop address in the CAM for the search. An indication of valid or invalid entries may be provided as well. Once the search is initiated by software, the search engine will read the entries sequentially starting from the programmed start address. It will perform a compare using the comparand-mask pair and attempt to identify a match. The locations in the CAM which match the search criteria may be put into a CPU-accessible memory. If the memory fills up before it can be read by the software, the search may be halted until the memory is emptied. A programmable action may instead, or in addition, be set to take place in the event of a match. Such programmable actions may include, but are not limited to, marking the entry, deleting the entry, change status bits corresponding to the entry, rewriting some of the entry, and the like.
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