Hi,
I'd like to share a case about route loop in this post.
Alarm
Customer Network device generated one alarm.
Jul 10 2018 11:55:19+05:30 Huawei Core Router PIPV4/4/CPCAR_TTL1_DROP(l)[23]:The number of packets sent to the CPU exceed the threshold 20000.(SLOT=0, CPCAR TYPE=CPCAR_TTL1, DiscardPacketCount=20072, Reason="A routing loop may occur")
Troubleshooting :
we can capture acl matched the ttl-expired packet and tracert the IP to find the loop.
acl number 3456
rule 5 permit ip ttl-expired
capture-packet acl 3456 destination terminal packet-num 200 packet-len 64
Warning: Mirrored packets will be shown on terminal.
Please help to make tracert on device .
<Huawei Core Router>Tracert xxx.x.119.192
traceroute to xxx.39.119.192(xxx.x.119.192), max hops: 30 ,packet length: 40,press CTRL_C to break
1 xxx.x.116.102 4 ms 3 ms 1 ms
2 xxx.x.116.97 1 ms 1 ms 2 ms
3 xxx.x.116.102 1 ms 1 ms 1 ms
4 xxx.x.116.97 3 ms 1 ms 2 ms
5 * * *
6 xxx.39.116.97 3 ms 1 ms 1 ms
Customer network existed route loop between xxx.x.116.102 and xxx.x.116.97.
Hope this could help you a lot.
Thanks!
