Search engine for forwarding table content addressable memory
US7274693B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 2002 |
| Grant date | Sep 25, 2007 |
| Priority date | — |
| Expiry date | Aug 2, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L49/90
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
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, cha…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.