Netgear XCM8810 Chassis Hardware Installation Guide - Page 1036

24. OSPFv3 Commands 24 This chapter describes commands used for the IPv6 interior gateway protocol OSPFv3. Open Shortest Path First (OSPFv3) is a link-state protocol that distributes routing information between routers belonging to a single IP domain, also known as an autonomous system (AS). In a link-state routing protocol, each router maintains a database describing the topology of the autonomous system. Each participating router in an area has an identical database maintained from the perspective of that router. OSPFv3 supports IPv6, and uses commands only slightly modified from that used to support IPv4. OSPFv3 has retained the use of the four-byte, dotted decimal numbers for router IDs, LSA IDs, and area IDs. From the link-state database (LSDB), each router constructs a tree of shortest paths, using itself as the root. The shortest path tree provides the route to each destination in the autonomous system. When several equal-cost routes to a destination exist, traffic can distributed among them. The cost of a route is described by a single metric. OSPFv3 allows parts of a networks to be grouped together into areas. The topology within an area is hidden from the rest of the autonomous system. Hiding this information enables a significant reduction in link-state advertisement (LSA) traffic, and reduces the computations needed to maintain the LSDB. Routing within the area is determined only by the topology of the area. The three types of routers defined by OSPFv3 are as follows: • Internal Router (IR)-An internal router has all of its interfaces within the same area. • Area Border Router (ABR)-An ABR has interfaces belonging to two or more areas. It is responsible for exchanging summary advertisements with other OSPFv3 routers. • Autonomous System Border Router (ASBR)-An ASBR acts as a gateway between OSPFv3 and other routing protocols, or other autonomous systems. Each switch that is configured to run OSPFv3 must have a unique router ID. It is recommended that you manually set the router ID of the switches participating in OSPFv3, instead of having the switch automatically choose its router ID based on the highest interface IPv4 address, since your router may not have an IPv4 address. Not performing this configuration in larger, dynamic environments could result in an older LSDB remaining in use. Chapter 24. OSPFv3 Commands | 1036