Network switch with hash table look up
US6457058B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 2001 |
| Grant date | Sep 24, 2002 |
| Priority date | — |
| Expiry date | Jul 12, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/4675
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An improved look up mechanism for accessing a RAM to obtain forwarding information for data frames being transported among ports of a high-performance switch is provided. The look up mechanism includes a multi-page look up table and associated hashing technique. A media access control (MAC) address and a virtual local area network (VLAN) identifier are transformed with a hash function to obtain a hash key. The hash key is an address pointing to a particular entry in the look up table. A virtual first page is also derived from the hash key, which selects a particular physical page of the look up table to be initially accessed each time that MAC address/VLAN pair is used. The look up mechanism may also be used to access a short cut table containing Layer 3 short cut information. In either case, ultimately, the likelihood is increased that a match will be found on the first RAM access, thus maintaining high-speed switch performance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.