EIGRP is a very popular routing protocol because it's easy to configure and manage. With minimal configuration and design, you can get an EIGRP network up and running that will serve your company for years to come. The ease of configuring EIGRP is also the main reason I see SO many misbehaving EIGRP networks in the field. A network engineer builds a small network for his company. As time goes on, the network gets larger and larger, and the routing environment gets more and more complicated. EIGRP manages the routing on the network quite nicely, until one day things start to go wrong. The engineer who built the network can't figure out what's wrong, and consultants are called in who completely redesign the network. This is not to say that EIGRP is not a good routing protocol; I believe it is a very strong protocol. My point is that it's almost too easy to configure. You can throw two EIGRP routers on an Ethernet LAN with minimal configuration, and they will communicate Specific Routing Protocols and share routes. You can do the same with 10 or 20 or 100 routers, and they will all communicate and share routes. You can add 100 serial links with remote sites using EIGRP, and they will all communicate and share routes. The routing table will be a mess and the routers may be converging constantly, but the packets will flow. Even- tually, however, the default settings may fail to work properly because the default con- figurations 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 equation, it is rarely a