282 CHAPTER 28: IP ROUTING P ROTOCOL OVERVIEWaddition, the running switch will automatically obtain some direct routesaccording to the port state and user configuration.Routing ManagementPolicyFor Switch 8800 Family series, you can configure manually the static route to aspecific destination, and configure dynamic routing protocol to interact with otherrouters on the network. The routing algorithm can also be used to discover routes.For the configured static routes and dynamic routes discovered by the routingprotocol, the Switch 8800 Family series implement unified management. That is,the static routes configured by the user are managed together with the dynamicroutes discovered by the routing protocol. The static routes and the routes learnedor configured by different routing protocols can also be shared with each other.Routing Protocols andthe Preferences of theCorresponding RoutesDifferent routing protocols (as well as the static configuration) may generatedifferent routes to the same destination, but not all these routes are optimal. Infact, at a certain moment, only one routing protocol can determine a current routeto a specific destination. Thus, each of these routing protocols (including the staticconfiguration) is set with a preference, and when there are multiple routinginformation sources, the route discovered by the routing protocol with the highestpreference will become the current route. Routing protocols and the defaultpreferences (the smaller the value is, the higher the preference is) of the routeslearned by them are shown in Table 248.In the table, 0 indicates a direct route. 255 indicates any route from unreliablesources.Apart from direct routing, IBGP and EBGP, the preferences of various dynamicrouting protocols can be manually configured to meet the user requirements. Inaddition, the preferences for individual static routes can be different.Supporting LoadSharing and RouteBackupLoad sharingThe Switch 8800 Family series support static equivalent route, permitting toconfigure multiple routes that reach the same destination and use the sameprecedence. After you configured static equivalent routes, a packet can reach thesame destination through multiple different paths, whose precedence levels areequal. When there is no route that can reach the same destination with a higherTable 248 Routing protocols and the default preferences for the routes learned by themRouting protocol or route type The preference of the corresponding routeDIRECT 0OSPF 10IS-IS 15STATIC 60RIP 100OSPF ASE 150OSPF NSSA 150IBGP 256EBGP 256UNKNOWN 255
