3Com 4007R Implementation Guide - Page 473

OSPF Interfaces 473 Statistics You can display interface statistics for diagnostic and network debugging purposes. Viewing the statistics for a particular interface can provide valuable information, such as whether the router is overburdened, and the number of Hello interval, dead interval, area ID, and password mismatches that the interface has seen on the network. For a complete listing of OSPF interface statistics, see the ip ospf interface statistics command in the Command Reference Guide. Important Considerations Designated routers Area ID Consider the following guidelines when you configure router interfaces: s To set the OSPF interface mode to active, enable IP routing. s Because designated routers and backup designated routers have the most OSPF work to do within an area, select routers that are not already loaded with CPU-intensive activities to be the designated router and backup designated router. s Because router priority is assigned on a per-interface basis, a single router with interfaces within several different areas can serve as designated router for those areas. But because a designated router has several CPU-intensive responsibilities, it is not a good idea to select the same router as designated router for many areas simultaneously. s Routers that have an interface priority of 0 cannot serve as a designated router or backup designated router. s On a broadcast network, if there is no designated router or backup designated router (such as when all routers have a priority of 0), routers do not form neighbor adjacencies, and routing information is not exchanged. s Set the area ID to the same value for all routers on the network segment. All routers in the same area must have the same area ID. s The backbone area 0.0.0.0 is configured by default. The system associates all newly defined OSPF interfaces with the backbone area. You can change this association by changing the area ID for the selected interface.