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Community Member

traceroute concern

when i do a traceroute to an ip on a different subnet on my LAN from a switch it displays a bunch of question marks. i can reach the ip if i ping it.

6 REPLIES

Re: traceroute concern

Can you please post here what you see?

Thanks,

Mohamad

Hall of Fame Super Gold

Re: traceroute concern

Eric

I agree that it would help if you post the output showing what you are doing and what the results are.

One thing that might produce the results that you describe is if devices in the path from your switch to the destination are configured with no ip unreachable. Remember that the way that traceroute works is that it sends probe packets controlling the Time To Live. It depends on the devices along the path to reduce the TTL and send error messages when TTL goes to zero. This is how we learn the steps along the path. But if the device is configured with no ip unreachable then when TTL goes to zero it discards the packet but does not send the error message. The question marks show steps in the path from which it did not receive responses. So in this case ping will work because you can get to the destination, but traceroute will not show the steps along the way.

HTH

Rick

Community Member

Re: traceroute concern

traceroute xx.xxx.xxx.40

Type escape sequence to abort.

Tracing the route to (xx.xxx.xxx.40)

1 ? ? ?

2 ? ? ?

3 * ? ?

4 ? * ?

5 ? ? *

6 ? ? ?

7 * ? ?

8 ? * ?

9 ? ? *

10 ? ? ?

11 * ? ?

12 ? * ?

13 ? ? *

14 ? ? ?

Community Member

Re: traceroute concern

the other thing is from the same remote switch i can successfully do a traceroute to another server on the same VM.

Re: traceroute concern

What's the model of the switch?

Thanks,

Mohamad

Community Member

Re: traceroute concern

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