It is possible to detect situation when two neigbour routers involved in EIGRP routing are configured by mistake with different AS number ?
I tried this situation practically. Two routers are connected together via Serial link network. One router has AS 1, other AS 10. I try to detect AS mismatch.
First I check what EIGRP packet are comming
debug ip packet detail show source <my neighbour IP address> destination 22.214.171.124 Ip protocol type 88. These packets are EIGRP Hello packet.
I try to go more deeply into details.
debug eigrp packets
I see only ongoing EIGRP Hello packets. But I don't see any incoming packet from my neighbour (which has different AS number). It seems, because of different AS number router silently drop eigrp packet.
Other debug eigrp command also doesn't show any info about AS difference.
Cisco IOS 12.4 (16)