 its version of the route will be inserted into the RIB. The administrative distances of the various routing protocols are shown in Table 10-1. Administrative Distance RIP cost: 3 (hops) 1.5 Mbps Gig fiber 1,000 Mbps OSPF cost: 1 + 1 +1 + 1 = 4 Figure 10-7. Competing routing protocols Table 10-1. Administrative distances of routing protocols Route type Administrative distance Connected interface Static route EIGRP summary route External BGP Internal EIGRP IS-IS External EIGRP Internal BGP Unknown A static route to a connected interface has an administrative distance of 0, and is the only route that will override a normal static route. A route sourced with an adminis- trative distance of 255 is not trusted, and will not be inserted into the routing table. Chapter 10: Routing Protocols Looking at Table 10-1, you can see that RIP has an administrative distance of 120, while OSPF has an administrative distance of 110. This means that even though the RIP route has a better metric in Figure 10-7, the route inserted into the routing table will be the one provided by OSPF. Specific Routing Protocols Entire books have been written on each of the routing protocols discussed in this chap- ter. My goal is not to teach you everything you need to know about the protocols, but rather to introduce them and show you what you need to know to get them operational. I'll also include some of the commands commonly used to troubleshoot these protocols. Routing protocols are divided into types based on their purpose and how they operate. The major division between routing protocols is that of internal gateway protocols versus external gateway protocols. An internal gateway protocol, or IGP, is designed to maintain routes within an auton- omous system. An autonomous system is any group of devices controlled by a single entity. An example might be a company or a school, but the organization does not need to be that broad-an autonomous system could be a floor in a building or a department in a company. Examples of IGPs include RIP, EIGRP, 