CCNP Routing and Switching ROUTE 300-101 Official Cert Guide

EIGRP Authentication

EIGRP authentication causes routers to authenticate every EIGRP message. To do so, the routers should use the same preshared key (PSK) and generate an MD5 digest for each EIGRP message based on that PSK. If a router configured for EIGRP authentication receives an EIGRP message, and the message’s MD5 digest does not pass the authentication checking based on the local copy of the key, the router silently discards the message. As a result, when authentication fails, two routers cannot become EIGRP neighbors, because they ignore each other’s EIGRP Hello messages.

From a design perspective, EIGRP authentication helps prevent denial of service (DoS) attacks, but it does not provide any privacy. The device that physically receives ...