Troubleshooting IGRP Issues

Router#debug ip igrp events	Shows all IGRP events in real time
Router#debug ip igrp transactions	Shows IGRP updates between routers

Caution:

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.