0,000,000 by the bandwidth of the link in bits per second (bps). The costs of some common links are therefore: 100 Mbps (100,000,000 / 100,000,000 bps) = 10 Mbps (100,000,000 / 10,000,000 bps) = 10 1.5 Mbps (100,000,000 / 1,540,000 bps) = 64 (results are rounded) Figure 10-6 shows the same network used in the RIP example. This time, OSPF is determining the best path to the destination network using bandwidth-based metrics. The metric for the T1 link is 64, and the metric for the gigabit link path is 4. Because Chapter 10: Routing Protocols Cost: 1 + 64 + 1 = 66 1.5 Mbps Gig fiber 1,000 Mbps OSPF prefers this path Cost: 1 + 1 +1 + 1 = 4 Figure 10-6. OSPF uses bandwidth to determine the best routes the metric for the link through Routers E, F, and G is lower than that for the link through Routers B and C, this path is inserted into the routing table. EIGRP uses a more complicated formula for determining costs. It can include band- width, delay, reliability, effective bandwidth, and maximum transmission unit (MTU) in its calculation of a metric. EIGRP is considered to be a hybrid protocol. Administrative Distance Networks often have more than one routing protocol active. In such situations, there is a high probability that the same networks will be advertised by multiple routing protocols. Figure 10-7 shows a network in which two routing protocols are running: the top half of the network is running RIP, and the bottom half is running OSPF. Router A will receive routes for the network 20.0.0.0 from RIP and OSPF. RIP's route has a better metric, but, as we've seen, OSPF has a better means of determining the proper path. So, how is the best route determined? Routers choose routes based on a predetermined set of rules. One of the factors in deciding which route to place in the routing table is administrative distance. Adminis- trative distance is a value assigned to every routing protocol. In the event of two pro- tocols reporting the same route, the routing protocol with the lowest administrative distance will win, and