D-Link DXS-5000-54S Emulator - Page 771

5000 Series Layer 2/3 Managed Data Center Switch CLI Reference Guide 7-180 nsf helper strict-Isa-checking The restarting router is unable to react to topology changes. In particular, the restarting router will not immediately update its forwarding table; therefore, a topology change may introduce forwarding loops or black holes that persist until the graceful restart completes. By exiting the graceful restart on a topology change, a router tries to eliminate the loops or black holes as quickly as possible by routing around the restarting router. A helpful neighbor considers a link down with the restarting router to be a topology change, regardless of the strict LSA checking configuration. Use this command to require that an OSPF helpful neighbor exit helper mode whenever a topology change occurs. Use the no command to allow OSPF to continue as a helpful neighbor in spite of topology changes. nsf [ietf] helper strict-lsa-checking no nsf [ietf] helper strict-lsa-checking Parameters ietf Default The default is Enabled. Command Mode OSPF Router Config (Optional) This keyword is accepted but not required. OSPFv2 Stub Router Commands 7-181 max-metric router-Isa To configure OSPF to enter stub router mode, use this command in Router OSPF Global Configuration mode. When OSPF is in stub router mode, as defined by RFC 3137, OSPF sets the metric in the nonstub links in its router LSA to Lslnfinity. Other routers therefore compute very long paths through the stub router, and prefer any alternate path. Doing so eliminates all transit traffic through the stub router, when alternate routes are available. Stub router mode is useful when adding or removing a router from a network or to avoid transient routes when a router reloads. You can administratively force OSPF into stub router mode, where it will remain until you take it out of stub router mode. Alternatively, you can configure OSPF to start in stub router mode for a configurable period of time after the router boots up. If you set the summary LSA metric to 16,777,215, other routers will skip the summary LSA when they compute routes. if you have configured the router to enter stub router mode on startup (max-metric router-Isa on-startup), and then enter max-metric router Isa, there is no change. If OSPF is administratively in stub router mode (the max-metric router-Isa command has been given), and you configure OSPF to enter stub router mode on startup (max-metric router-Isa on-startup), OSPF exits stub router mode (assuming the startup period has expired) and the configuration is updated. 765