IGRP

Interior Gateway Routing Protocol. A popular classful Cisco-propriatory routing protocol. A good alternative to RIP.

router igrp 100 (example of the command used at a Cisco IOS prompt)

igrp

Interior Gateway Routing Protocol (IGRP) is a distance vector interior gateway protocol (IGP) developed by Cisco. It is used by routers to exchange routing data within an autonomous system.

Joshua likes IGRP because it is considered a classful routing protocol.