IP Routing Protocol Overview 105In a complicated Internet configuration, as shown in Figure 31, the number ineach network is the network address. The router R8 is connected to threenetworks, so it has three IP addresses and three physical ports. Its routing table isshown in Figure 2.Figure 31 The routing tableThe Switch 4500 can automatically obtain some direct routes according to theinterface state and user configuration.Routing ManagementPolicyYou can manually configure a static route to a certain destination or configure theinteraction between dynamic routing protocol and other routers in your networkand find a route via routing algorithm. The static routes configured by the user aremanaged together with the dynamic routes discovered by the routing protocol inthe router. The static routes and the routes learned or configured by differentrouting protocols can also be shared among routing protocols.Routing Protocols and Route PreferencesRouting protocols (including static routes) can generate different routes to thesame destination, but not all these routes are optimal. In fact, at a certainmoment, only one routing protocol can determine a current route to a singledestination. Thus, each routing protocol (including static routes) has a setpreference, and when there are multiple routing information sources, the routewith the highest preference becomes the current route. Routing protocols and thedefault preferences of the routes that they learn are shown in Table 99. Thesmaller the value, the higher the preference).Except for direct routing, the preferences of various dynamic routing protocols canbe manually configured to meet the user requirements. The preferences forindividual static routes can be different.Forwarding Portrouter passed10.0.0.0 Directly11.0.0.012.0.0.0 11.0.0.213.0.0.0 314.0.0.0 13.0.0.2 315.0.0.0 10.0.0.2 216.0.0.0 10.0.0.2 215.0.0.016.0.0.010.0.0.013.0.0.012.0.0.014.0.0.011.0.0.0R4R1R3R2R6R5R7R8111.0.0.2212.0.0.112.0.0.212.0.0.314.0.0.114.0.0.213.0.0.113.0.0.4 11.0.0.1310.0.0.110.0.0.216.0.0.316.0.0.215.0.0.215.0.0.1 13.0.0.216.0.0.213.0.0.3The routing table of router R8DestinationhostlocationDirectlyDirectly211Forwarding Portrouter passed10.0.0.0 Directly11.0.0.012.0.0.0 11.0.0.213.0.0.0 314.0.0.0 13.0.0.2 315.0.0.0 10.0.0.2 216.0.0.0 10.0.0.2 215.0.0.016.0.0.010.0.0.013.0.0.012.0.0.014.0.0.011.0.0.0R4R1R3R2R6R5R7R8111.0.0.2212.0.0.112.0.0.212.0.0.314.0.0.114.0.0.213.0.0.113.0.0.4 11.0.0.1310.0.0.110.0.0.216.0.0.316.0.0.215.0.0.215.0.0.1 13.0.0.216.0.0.213.0.0.3The routing table of router R8DestinationhostlocationDirectlyDirectly211Table 99 Routing Protocols and the Default Preferences for RoutesRouting protocol or route type The preference of the corresponding routeDIRECT 0STATIC 60UNKNOWN 255
