 based. In a Cisco router, the routing table is called the route information base (RIB). When you execute the command show ip route, the output you receive is a formatted view of the information in the RIB. Each routing protocol has its own table of information. For example, EIGRP has the topology table, and OSPF has the OSPF database. Each protocol makes decisions on what routes will be held in its database. Routing protocols use their own metrics to determine which route is the best route, and the metrics vary widely. The metric Chapter 9: Routing and Routers value is determined by the routing protocol from which the route was learned. Thus, the same link may have very different metrics depending on the protocol used. For example, the same path may be described with a metric of 2 in RIP, 200 in OSPF, and 156160 in EIGRP. Routing protocols and metrics are covered in more detail in Chapter 10. If the same route is learned from two sources within a single routing protocol, the one with the best metric will win. Should the same route be learned from two routing protocols within a single router, the protocol with the lowest administrative distance will win. The administrative distance is the value assigned to each routing protocol to allow the router to prioritize routes learned from multiple sources. The administra- tive distances for the various routing protocols are shown in in Table 9-1. Table 9-1. Routing protocols and their administrative distances Route type Administrative distance Connected interface Static route Enhanced Interior Gateway Routing Protocol (EIGRP) summary route External Border Gateway Protocol (BGP) Internal EIGRP Interior Gateway Routing Protocol (IGRP) Open Shortest Path First (OSPF) Intermediate System-Intermediate System (IS-IS) Routing Information Protocol (RIP) Exterior Gateway Protocol (EGP) On Demand Routing (ODR) External EIGRP Internal BGP Unknown Spanning tree, discussed in Chapter 8, isn't really a routing protocol because the protocol doesn't care about the data being passed; spa