Nokia Network Voyager for IPSO 4.0 Reference Guide 401NoteIf the backbone is running OSPF as well, you can enable aggregation only by configuringthe 192.168.24.0 network in a different OSPF Area.Route RankThe route rank is the value that the routing subsystem uses to order routes from differentprotocols to the same destination.You cannot use rank to control the selection of routes within a dynamic interior gateway protocol(IGP); this is accomplished automatically by the protocol and is based on the protocol metric.You can use rank to select routes from the same external gateway protocol (EGP) learned fromdifferent peers or autonomous systems.The rank value is an arbitrarily assigned value used to determine the order of routes to the samedestination in a single routing database. Each route has only one rank associated with it, eventhough rank can be set at many places in the configuration. The route derives its rank from themost specific route match among all configurations.The active route is the route installed into the kernel forwarding table by the routing subsystem.In the case where the same route is contributed by more than one protocol, the one with thelowest rank becomes the active route.Some protocols—BGP and aggregates—allow for routes with the same rank. To choose theactive route in these cases, a separate tie breaker is used. This tie breaker is called LocalPref forBGP and weight for aggregates.Rank AssignmentsA default rank is assigned to each protocol. Rank values range from 0 to 255, with the lowestnumber indicating the most preferred route.The table below summarizes the default rank values.Preference of DefaultInterface routes 0OSPF routes 10Static routes 60IGRP routes 80RIP routes 100Aggregate routes 130
