Method and apparatus for performing a graceful restart in a NSF-capable router without enhancing link state routing protocols
AssigneeGeneral Instrument Corporation
InventorBilly Ng
Life of this patent
Estimating the term…
Abstract
A graceful restart is provided in a NSF capable router. When a switchover to a standby controller is required, the standby controller receives replicated link state message headers from an active controller. The standby controller generates a link state request (LSR) message from the link state message headers and transmits the LSRs to neighboring routers. The standby controller receives a link state update that includes the link state messages. By using the LSRs, the standby controller can be quickly synchronized with its neighbors well within the grace period, thereby maintaining adjacency.
Claims20
A method of migrating link state routing processes from an active controller to a standby controller in a Non-Stop Forwarding (NFS)-capable router, comprising:
- establishing an adjacency relationship between the router and at least one neighboring router;
- replicating, in the standby controller, link state message headers acquired by the active controller when establishing the adjacency relationship;
- identifying from the link state message headers in the standby controller any missing link state messages that are needed to maintain the adjacency relationship;
- generating a Link State Request (LSR) requesting the missing link state messages;
- transmitting the LSR to the at least one neighboring router;
- and
- in response to the transmitted LSR, receiving a Link State Update (LSU) that includes the missing link state messages.
A router, comprising:
- a forwarding engine for forwarding packets to neighboring routers in a network;
- a first routing controller processor operatively coupled to the forwarding engine for running routing protocol processes;
- a standby routing controller operatively coupled to the first routing controller and the forwarding engine for running routing protocol processes;
- and
- wherein the standby routing controller is configured to perform a graceful restart by transmitting to neighboring routers a Link State Request (LSR) requesting missing link state messages identified from previously received link state message headers.
Dependencies are inferred from the claim text.