Chapter content summary: EIGRP is a classless routing protocol that supports VLSM; path selection is based upon several factors; EIGRP keeps a next-best alternative path, called a feasible successor, for fast convergence; EIGRP supports unequal-cost load balancing; EIGRP uses MD5 authentication for router authenticity; troubleshooting EIGRP requires resolving link, neighbor, redistribution, and routing issues. | EIGRP Implementation Implementing EIGRP EIGRP Features Flexible network design Multicast and unicast instead of broadcast address Support for VLSM and discontiguous subnets Manual summarization at any point in the internetwork Support for multiple network layer protocols Advanced distance vector Rapid convergence 100% loop-free classless routing Easy configuration Incremental updates Load balancing across equal- and unequal-cost pathways EIGRP Tables EIGRP Path Calculation (Router C) EIGRP Configuration RouterX(config)# router eigrp autonomous-system RouterX(config-router)# network network-number Purpose: The figure shows how the IGRP commands operate on the example network. Emphasize: An administrator only specifies directly connected networks that should be published to other routers. Without the network command, nothing is advertised. With a network command, the router will advertise every subnet within the Class A, B, or C network specified in the configuration. EIGRP and . | EIGRP Implementation Implementing EIGRP EIGRP Features Flexible network design Multicast and unicast instead of broadcast address Support for VLSM and discontiguous subnets Manual summarization at any point in the internetwork Support for multiple network layer protocols Advanced distance vector Rapid convergence 100% loop-free classless routing Easy configuration Incremental updates Load balancing across equal- and unequal-cost pathways EIGRP Tables EIGRP Path Calculation (Router C) EIGRP Configuration RouterX(config)# router eigrp autonomous-system RouterX(config-router)# network network-number Purpose: The figure shows how the IGRP commands operate on the example network. Emphasize: An administrator only specifies directly connected networks that should be published to other routers. Without the network command, nothing is advertised. With a network command, the router will advertise every subnet within the Class A, B, or C network specified in the configuration. EIGRP and Discontiguous Networks Default Scenario Configuration EIGRP, by default, does not advertise subnets and, therefore, cannot support discontiguous subnets. EIGRP and Discontiguous Networks with no auto-summary EIGRP with the no auto-summary parameter can advertise subnets and, therefore, can support discontiguous subnets. RouterX# show ip eigrp interfaces IP EIGRP interfaces for process 109 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Di0 0 0/0 0 11/434 0 0 Et0 1 0/0 337 0/10 0 0 SE0: 1 0/0 10 1/63 103 0 Tu0 1 0/0 330 0/16 0 0 Verifying the EIGRP Configuration RouterX# show ip eigrp interfaces Displays information about interfaces configured for EIGRP RouterX# show ip protocols RouterX# show ip
