Traceroute / ICMP Question

[Alexander Deems]

I am trying to get a better understanding of how to read this traceroute because there is nothing blocking icmp on the test network I have setup. I am also not sure why there are multiple entries for hop 4. Shouldn't there only be a single hop?

R1#traceroute 6.6.6.6

Type escape sequence to abort.

Tracing the route to 6.6.6.6

  1  *  *  *

  2  *  *  *

  3  *  *  *

  4 10.5.6.6 240 msec

    10.6.7.6  232 msec

    10.5.6.6  212 msec

Thank you,

Alex

[cadet alain · Accepted solution]

Hi,

Cisco IOS uses UDP for traceroute not ICMP and it sends 3 probes with same TTL to different udp destination ports so that's why you see the 2 different IP adresses because you have 2 paths to destination.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_tech_note09186a00800a6057.shtml#traceroute

Regards

Alain

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