Dell PowerConnect 8100 User's Configuration Guide - Page 946

OSPF Feature Details This section provides details on the following OSPF features: • Max Metric • Static Area Range Cost • LSA Pacing • LSA Pacing Max Metric RFC 3137 introduced stub router behavior to OSPFv2. As a stub, a router can inform other routers that it is not available to forward data packets. This can be useful if OSPF has run out of resources (for example, memory) to compute a complete routing table, or to avoid routing transients as OSPF learns its neighbors and a complete set of routes at startup. Thus, OSPF can enter stub router mode either automatically (as a result of a resource condition) or by configuration. When OSPF enters stub router mode, it re-originates its router LSAs and sets the metric on each of its non-stub links to the maximum value, 0xFFFF. Whenever OSPF originates a router LSA while in stub router mode, it sets the metrics in this way. Stub router mode is global and applies to router LSAs for all areas. Other routers prefer alternate paths that avoid the stub router; however, if no alternate path is available, another router may compute a transit route through a stub router. Because the stub router does not adjust the metric for stub links in its router LSA, routes to destinations on these networks are unaffected. Thus, stub router mode does not affect management connections to the router, even if the router and management station depend on OSPF routes to communicate with each other. The feature supports two modes of operation. The network administrator can put OSPF in stub router mode. OSPF remains in stub router mode until the network administrator takes OSPF out of stub router mode. Alternatively, the network administrator can configure OSPF to start in stub router mode for a configurable period of time after the router boots up. On a stack, the startup period also applies when a unit takes over as the management unit. The clear configuration command also restarts OSPF in stub router 946 Configuring OSPF and OSPFv3