Advanced Infrastructure Penetration Testing

Enhanced Interior Gateway Routing Protocol

The Enhanced Interior Gateway Routing Protocol (EIGRP) is an enhanced version of IGRP. It uses the dual algorithm. Routers use neighbors using Hello requests, while there are five message types (hello, update, ack, query, and reply). The following diagram shows how EIGRP works:

EIGRP maintains the following three tables:

• Neighbor table
• Topology table
• Routing table

EIGRP calculates the cost to choose the routes using the following formula:

metric = bandwidth + delay

Although IGRP does not support authentication, EIGRP has added two major security features—plaintext and MD5 authentication forms. ...