Chapter 2. EIGRP Theory and Operation
Enhanced Interior Gateway Protocol (EIGRP) is a widely used advanced distance vector routing protocol. This chapter provides a high-level overview of the theory and operation of EIGRP.
EIGRP forms neighbor relationships for two primary reasons:
• To maintain state about reachable destinations and paths without periodically retransmitting this information
• To provide a reliable mechanism to process the loss of reachability information
EIGRP uses a three-way handshake process to build a neighbor adjacency, as shown in Figure 2-1.
Once EIGRP neighbors ...