Operation Manual – IP Routing-GR OverviewH3C S5500-EI Series Ethernet Switches Chapter 1 IP Routing Overview1-6II. Route backupRoute backup can help improve network reliability. With route backup, you canconfigure multiple routes to the same destination, expecting the one with the highestpriority to be the main route and all the rest backup routes.Under normal circumstances, packets are forwarded through the main route. When themain route goes down, the route with the highest priority among the backup routes isselected to forward packets. When the main route recovers, the route selection processis performed again and the main route is selected again to forward packets.1.2.5 Route RecursionThe nexthops of some BGP routes (except EBGP routes) and static routes configuredwith nexthops may not be directly connected. To forward the packets, the outgoinginterface to reach the nexthop must be available. Route recursion is used to find theoutgoing interface based on the nexthop information of the route. Link-state routingprotocols, such as OSPF and IS-IS, do not need route recursion because they obtainnexthop information through route calculation.1.2.6 Sharing of Routing InformationAs different routing protocols use different routing algorithms to calculate routes, theymay find different routes. In a large network with multiple routing protocols, it is requiredfor routing protocols to share their routing information. Each routing protocol has itsown route redistribution mechanism. For detailed information, refer to the descriptionabout route redistribution in each routing protocol.1.3 Displaying and Maintaining a Routing TableTo do… Use the command… RemarksDisplay brief informationabout the active routes inthe routing tabledisplay ip routing-table[ verbose | | { begin | exclude |include } regular-expression ]Display information aboutroutes to the specifieddestinationdisplay ip routing-tableip-address [ mask-length |mask ] [ longer-match ][ verbose ]Display information aboutroutes with destinationaddresses in the specifiedrangedisplay ip routing-tableip-address1 { mask-length |mask } ip-address2{ mask-length | mask }[ verbose ]Display information aboutroutes permitted by anIPv4 basic ACLdisplay ip routing-table aclacl-number [ verbose ]Available in anyview
