Chapter 8: Troubleshooting EIGRP Routing Environments

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In This Chapter

• Features of EIGRP

• Problem Isolation in EIGRP

• Misconfiguration in EIGRP

• EIGRP Neighbor Formation Problem

• EIGRP Route Problem

• EIGRP Metric Problem

• Stuck in Active State

• Redistribution Problem

Enhanced Interior Routing Gateway Protocol (EIGRP) is a Cisco-proprietary Interior Gateway Protocol (IGP). It is a highly advanced distance vector routing protocol that scales well to larger internetworks. EIGRP uses the Diffused Update Algorithm (DUAL) to calculate the best path to a destination network, thereby reducing overheads associated with other IGPs. The network resource utilization is reduced as well, because only Hello packets are exchanged between neighbors. In case of a change in the routing table, only the change is propagated instead of the whole routing table, ensuring minimum bandwidth utilization. The EIGRP algorithm also ensures fast convergence in case of any changes in network topology.

EIGRP is widely deployed around the world in large Cisco-only networks. This chapter discusses the various problems, their effective isolation, and the different methods to resolve problems.