Router#debug ip igrp events
Shows all IGRP events in real time
Router#debug ip igrp transactions
Shows IGRP updates between routers
IGRP as a routing protocol is no longer supported by Cisco as of Cisco IOS Software Release 12.3. If you are using Cisco IOS 12.3 or newer code, you must use either Enhanced IGRP (EIGRP) or one of the other standardsRIP-1, RIP-2, or OSPF.