Debugging router neighbors can get tricky, especially when debugging on a headend router that has a log of neighbors. However, you can debug traffic coming from just one neighbor.
First, enable debugging on all eigrp packets with this cmd:
debug eigrp packets
Second, narrow down your debug to just one neighbor:
debug ip eigrp neighbor a.b.c.d
The trick here is to combine the “debug eigrp” wth “debug ip eigrp”. And IOS will let you know if you do it wrong too. In 12.4, If you put the second cmd in first, it’ll throw this back at you:
First enable IP-EIGRP Route Events or EIGRP packet debug
However, in 15.0, you’ll get no such complaints. Either way, once you’re done with this, just “term mon” and you’re done!