Fault management refers to the reconfiguration of the Internet Protocol (IP) network in instances of node or link loss, and the reconfiguration of the router when failure of the processor card supporting the control plane occurs (Figure 6.1).
The first part of this chapter presents the protocols known as HSRP (Hot Standby Router Protocol) and VRRP (Virtual Router Redundancy Protocol), implemented at the routers providing the interconnection between the local area (LANs) and wide are networks (WANs). This protocol allows the interconnection routers to be presented to terminal stations as a single virtual router, in order not to modify their configuration (IP address of the gateway router).
The second part presents the OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol) routing protocols, which carry out the reconfiguration of the network when the fault occurs inside the WAN (same autonomous systems (AS)), or between several operators’ WANs (inter-AS). This is obtained by updating the RIB and FIB tables following a modification of the network’s topology.
The third part describes the internal reconfiguration of a router implementing control processor switchover mechanisms. The following arrangements have been defined for the routing protocols:
– the Restart Signaling mechanism for the OSPF protocol;
– the Graceful Restart mechanism for the OSPF and BGP protocols.