Traceroute ....

Answered Question
Nov 18th, 2008
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Hi,

I have a question with regards to traceroute ... When I do a traceroute, at times I see something lke this ...


1 10.10.10.10 4 msec 0 msec 4 msec

10.10.10.11 4 msec 0 msec 4 msec

10.10.10.10 4 msec 0 msec 4 msec

2 10.10.11.1 0 msec 0 msec 0 msec

10.10.11.2

10.10.11.1

3 172.31.2.4 16 msec 4 msec 8 msec


My questions is why are we seeing 3 IPs like in the 1st hop ? What does it mean ?


Thank you,


Cheers,

- InternetB -

Correct Answer by Jon Marshall about 8 years 6 months ago

You will see this when the router has multiple paths to the same destination.


So if you log onto the first hop router and and do a "sh ip route" you should see 2 next-hops for the destination IP address you are tracerouting to.


Jon

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Correct Answer
Jon Marshall Tue, 11/18/2008 - 19:51
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You will see this when the router has multiple paths to the same destination.


So if you log onto the first hop router and and do a "sh ip route" you should see 2 next-hops for the destination IP address you are tracerouting to.


Jon

royalblues Tue, 11/18/2008 - 23:08
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Just to add to Jon's post that this will be the case only when you try to trace from a cisco device and not from a desktop.


This is because the packets originated from the cisco device are process switched and hence the 3 trace probes are sent in a loadbalanced fashion.


Trace packets from a desktop would be CEF switched to a flow path already established and will not exhibit this behavior


Narayan

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