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How to troubleshooting route loop?

Latest reply: Jul 28, 2018 06:56:19 1750 2 0 0 0


I'd like to share a case about route loop in this post.


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.


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Created Jul 24, 2018 03:42:18


What is the device .116.102 and what is the device .116.97. Could you explaine a simple connection scheme?
Share here on the .116.97 a result of command:

display ip routing-table xxx.39.119.192
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Created Jul 28, 2018 06:56:19

hi bro, can all devices use this way check route loop? any limitations?
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  • x
  • convention:


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