| US 7,362,700 B2 | ||
| Methods and systems for hitless restart of layer 3 packet forwarding | ||
| John Kevin Frick, Raleigh, N.C. (US); Donald B. Grosser, Apex, N.C. (US); and Michael D. Mroz, Fuquay-Varina, N.C. (US) | ||
| Assigned to Extreme Networks, Inc., Santa Clara, Calif. (US) | ||
| Filed on Jun. 27, 2002, as Appl. No. 10/184,483. | ||
| Prior Publication US 2004/0001485 A1, Jan. 01, 2004 | ||
| Int. Cl. G06F 11/00 (2006.01) | ||
| U.S. Cl. 370—219 [370/352; 370/401] | 37 Claims |
| 1. A method for hitless restart of layer 3 packet forwarding in response to failure of a management service module, the method comprising:
(a) at a master management service module:
(i) building a first routing table by participating in layer 3 routing protocols and storing the first routing table in memory,
(ii) building a first layer 3 forwarding table by receiving packets, performing lookups in the first routing table, and storing results from the lookups
in hardware, and
(iii) replicating the first layer 3 forwarding table to a slave management service module, and
(iv) forwarding packets using the first routing and forwarding tables; and
(b) at the slave management service module:
(i) maintaining the replicated first layer 3 forwarding table received from the master management service module, and
(ii) detecting failure of the master management service module and, in response, continuing forwarding of packets using the
hardware copy of the first layer 3 forwarding table, initiating construction of a second routing table by beginning to participate in layer 3 routing protocols, and linking entries in the second routing table with the replicated first layer 3 forwarding table.
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