Configuring Routing 551– Timed Out—The previous graceful restart timed out.– Topology Changed— The previous graceful restart terminated prematurely because of a topologychange.If you change the Support Mode, click Submit to save your change.Click Refresh to redisplay the page with the latest values from the switch.Enabling the NSF OSPF Graceful Restart Using CLI CommandsFor information about the CLI command that performs this function, see the following chapter in theCLI Reference Guide:• OSPF CommandsThe following table summarizes the equivalent CLI commands for this feature.BOOTP/DHCP Relay AgentBootP/DHCP Relay Agent enables BootP/DHCP clients and servers to exchange BootP/DHCP messagesacross different subnets. The relay agent receives the requests from the clients, and checks the valid hopsand giaddr fields. If the number of hops is greater than the configured, the agent assumes the packet islooped through the agents and discards the packet. If giaddr field is zero the agent must fill in this fieldwith the IP address of the interface on which the request was received. The agent unicasts the validpackets to the next configured destination. The server responds with a unicast BOOTREPLY addressedto the relay agent closest to the client as indicated by giaddr field. Upon reception of the BOOTREPLYfrom the server, the agent forwards this reply as broadcast or unicast on the interface form where theBOOTREQUEST was arrived. This interface can be identified by giaddr field.T he PowerConnect 6200 Series DHCP component also supports DHCP relay agent options to identifythe source circuit when customers are connected to the Internet with high-speed modem. The relayagent inserts these options when forwarding the request to the server and removes them when sendingthe reply to the clients.If an interface has more than one IP address, the relay agent should use the primary IP addressconfigured as its relay agent IP address.Table 9-19. NSF OSPF Graceful Restart CommandCLI Command Descriptionnsf Enables non-stop forwarding.nsf helper Enables helpful neighbor functionality for the OSPF protocol.nsf helper strict-lsa-checking Requires that an OSPF helpful neighbor exit helper mode whenever atopology change occurs.show ip ospf Displays information relevant to the OSPF router.show ip ospf neighbor This command displays information about OSPF neighbors.
