 good idea to do SO. EIGRP converges very quickly, even in large networks. 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 identifies the instance of EIGRP. A router can have multiple instances of EIGRP 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 that of RIP in that RIP runs globally on the router. Figure 10-11 shows a router with two instances of EIGRP active. Each instance is ref- erenced 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. For a route learned in one process to be known to the other, the router must be configured 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 Router A EIGRP: 200 10.20.20.0/24 Figure 10-11. Multiple EIGRP instances Chapter 10: Routing Protocols As with all IGPs, you list the interfaces you wish to include using the network command. EIGRP, like RIP, will automatically convert a classless network into the classful equivalent. The difference is that with EIGRP, you can add an inverse subnet mask to make the entry more specific. The following commands add all interfaces with ad- dresses in the 10.0.0.0 network to the EIGRP 100 process: Router-A(config)#router eigrp 100 Router-A(config-router)# network 10.0.0.0 But in the example in Figure 10-11, we'd like to add only the interface with the network 10.10.10.0/24. The subnet mask for a /24 network is 255.255.255.0, and the inverse subnet mask is 0.0.0.255 (inverse subnet masks are also called wildcard masks, and are discussed in Chapter 23). So, to add only t