DELL N3000 User Manual

Configuring OSPF and OSPFv3

This section provides details on the following OSPF features:

• Max  Metric
• Static Area Range Cost
• LSA  Pacing
• LSA  Pacing

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