H3C S5120-EI Series Configuration Manual

Also see for S5120-EI Series: Installation manual Configuration guide Configuration guide Operation manual Configuration guide

Contents

H3C S5120-EI Series Configuration Manual Manual pdf 14 page image

14Static routing configurationIntroductionStatic routeA static route is manually configured, but if a network’s topology is simple, you only need to configurestatic routes for the network to function. The proper configuration and usage of static routes can improvenetwork performance and ensure bandwidth for important network applications.The disadvantage of using static routes is that they cannot adapt to network topology changes. If a faultor a topological change occurs in the network, the routes will be unreachable and the network breaks. Inthe event of a fault or topological change, the network administrator has to modify the static routesmanually.The term router in this document refers to a router in a generic sense or a Layer 3 switch.Default routeIf the packet’s destination address fails to match any entry in the routing table, the packet is discarded.After a default route is configured on a router, any packet whose destination IP address matches no entryin the routing table can be forwarded to a designated upstream router.A router selects the default route only when it cannot find any matching entry in the routing table.• If the destination address of a packet fails to match any entry in the routing table, the router selectsthe default route to forward the packet.• If there is no default route and the destination address of the packet fails to match any entry in therouting table, the packet will be discarded and an ICMP packet will be sent to the source to reportthat the destination or the network is unreachable.You can configure a default route with both the destination and mask being 0.0.0.0. The router forwardsany packet whose destination address fails to match any entry in the routing table to the next hop of thedefault static route.Application environment of static routingBefore configuring a static route, you need to know the following concepts:• Destination address and mask:In the ip route-static command, an IPv4 address is in dotted decimal format and a mask can beeither in dotted decimal format or in the form of mask length (the number of consecutive 1s in themask).• Output interface and next hop address: