e routes. The rout- ing table will be a mess and the routers may be converging constantly, but the pack- ets will flow. Eventually, however, the default settings may fail to work properly because the default configurations are not designed to scale in massive networks. When EIGRP is configured properly on a network with a well-designed IP address scheme, it can be an excellent protocol for even a large network. When configured with multiple processes, it can scale very well. EIGRP is a hybrid routing protocol that combines features from distance-vector pro- tocols with features usually seen in link-state protocols. EIGRP uses triggered updates, SO updates are sent only when changes occur. Bandwidth and delay are used as the default metrics, and although you can add other attributes to the equa- tion, it is rarely a good idea to do SO. EIGRP converges very quickly even in large net- works. A network that might take minutes to converge with RIP will converge in seconds with EIGRP. To configure EIGRP, enter into router configuration mode with the router eigrp autonomous-system-number command. The autonomous system number is a number that identifies the instance of EIGRP. A router can have multiple instances of EIGRP Specific Routing Protocols running on it, each with its own database containing routes. The router will choose the best route based on criteria such as metrics, administrative distance, and SO on. This behavior is different from RIP's, in that RIP runs globally on the router. Figure 10-11 shows a router with two instances of EIGRP active. Each instance referenced by an ASN. Routes learned in one process are not shared with the other process by default. Each process is essentially its own routing protocol. In order for a route learned in one process to be known to the other, the router must be config- ured for redistribution. EIGRP will redistribute IGRP routes automatically within the same ASN. (Redistribution is covered in detail in Chapter 11.) 10.10.10.0/24 EIGRP 100 192.168.1.0/24 192.168.2.0/24 Rout