H3C s5120-si series Configuration Manual

Also see for S5120-SI Series: Quick start guide Installation manual Operation manual Command reference Configuration guide

Contents

H3C s5120-si series Configuration Manual Manual pdf 8 page image

1IP routing basicsNOTE:The termrouter in this document refers to a routing-capable device.IP routing overviewRoutingRouting in the Internet is achieved through routers. Upon receiving a packet, a router determines theoptimal path based on the destination address and forwards the packet to the next router in the path.When the packet reaches the last router, it then forwards the packet to the intended destination host.Routing provides the path information that guides the forwarding of packets.Routing table and FIB tableThe routing table plays a key role in route selection and the forwarding information base (FIB) table playsa key role in packet forwarding. Each router maintains a routing table and a FIB table.Routes in a routing table can be divided into the following categories by origin:• Direct routes—Routes discovered by data link protocols, also known as "interface routes"• Static routes—Routes that are manually configured• Dynamic routes—Routes that are discovered dynamically by routing protocolsEach entry in the FIB table specifies a physical interface that packets destined for a certain addressshould go out to reach the next hop—the next router—or the directly connected destination.Introduction to routing tableEach router maintains a local routing table, and each routing protocol maintains a protocol routing table.• Routing table of a protocolA protocol routing table stores routes discovered by the routing protocol.• Local routing tableA local routing table stores the routes found by all protocols and delivers the optimal routes to the FIBtable to guide packet forwarding. The optimal route selection is based on the routing protocolpreferences and route metrics.