How can I verify traffic is reaching and returning from a destination?

[joshualoatman]

I have a cisco 3825 (ver 12.4(8c) that connects to a cisco 7206VXR(ver 12.4(24)T5) through a cloud carrier service.

How can I run a test to verify that packets from the 3825 are reaching the 7206 and that the 7206 is responding back to the 3825?

For example, if I send a ping from the  3825 and I get a time out how can I verify if the 7206 received the packet?

I know with firewalls you can do a tcpdump but can you do something similar on routers?

[Joseph W. Doherty]

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Posting

You might try an ingress and/or egress ACL, and match the ICMP request/reply packets (look for hits on the ACL).

Later IOS versions also include embedded packet capture - your 12.4T version might support.

[Karsten Iwen]

For things like these I typically enable the debug for ICMP on the target device and then I ping it. If I see the echo-request, then at least the first way is ok.

But before starting any debugs it's always a good idea to make sure the box is not under heavy load.

[Mukesh Kumar]

Hello joshualoatman

It will be good to create an ACL, in which you have to match exact source and destination ip address and then debug only the traffic of that ACL by using the following command:

debug ip packet <acl number>

Even you can use traceroute to verify where your data packet is dropping.

Regards,
Mukesh Kumar
Network Engineer
Spooster IT Services

[paul driver · Accepted solution]

Hello

access-list 100 permit Icmp host x.x.x.x host y.y.y.y

access-list 100 permit Icmp host y.y.y.y host x.x.x.x

debug ip packet detail 100

ping y.y.y.y source.x.x.x.x repeat 2

res

paul