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New Member

Traceroute versus Extended Traceroute

Heloo

I was wondering why a regular traceroute to Google dns (8.8.8.8) fails to go past first hop, but an extended traceroute to google dns (8.8.8.8)

gets all the way to hop (1) before dropping?

sMc
2 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Silver

Traceroute versus Extended Traceroute

It would help if you would tell us what options you chose in extended traceroute. If the behavior was different then something changed. Perhaps it was an option that you chose in extended traceroute. Or perhaps it was something that changed in the network. Did you try both a couple of times to verify that the issue is repeatable and therefore something about extended traceroute rather than some external thing?

HTH

Rick

Hall of Fame Super Silver

Traceroute versus Extended Traceroute

Thanks for the additional information. I believe that it does show us why the behavior was different. By default the Cisco device will use the IP address of the outgoing interface as the source address for the traceroute. In the extended traceroute you specified an IP address for the source address (and I am assuming that it was not the address of the outgoing interface). When the source address was the outgoing interface the traceroute did not work and when the source address was 10.42.21.101 then it did work.

We can not say at this point what causes the regular traceroute to fail, but it could easily be that the specified address is being translated and the outgoing interface address is not. Or it might be a security policy that is denying the address of the outgoing interface.  Or it might be something else.

HTH

Rick

4 REPLIES
Hall of Fame Super Silver

Traceroute versus Extended Traceroute

It would help if you would tell us what options you chose in extended traceroute. If the behavior was different then something changed. Perhaps it was an option that you chose in extended traceroute. Or perhaps it was something that changed in the network. Did you try both a couple of times to verify that the issue is repeatable and therefore something about extended traceroute rather than some external thing?

HTH

Rick

New Member

Traceroute versus Extended Traceroute

Rick

Thank you for the reply

Here is the process I used. I have repeated this with same result.

Site_1#traceroute 8.8.8.8

Type escape sequence to abort.

Tracing the route to 8.8.8.8

VRF info: (vrf in name/id, vrf out name/id)

  1 10.254.0.9 [AS 64531] 60 msec 60 msec 60 msec

  2  *  *  *

  3  *  *

Site_1#traceroute

Protocol [ip]:

Target IP address: 8.8.8.8

Source address: 10.42.21.101 - LAN interface ip address on WAN router

Numeric display [n]:

Timeout in seconds [3]:

Probe count [3]:

Minimum Time to Live [1]:

Maximum Time to Live [30]:

Port Number [33434]:

Loose, Strict, Record, Timestamp, Verbose[none]:

Type escape sequence to abort.

Tracing the route to 8.8.8.8

VRF info: (vrf in name/id, vrf out name/id)

  1 10.254.0.9 [AS 64531] 60 msec 60 msec 64 msec

  2 10.44.41.1 [AS 64554] 64 msec 60 msec 60 msec

  3 66.195.148.1 [AS 64531] 60 msec 60 msec 60 msec

  4 207.250.147.249 [AS 64531] 64 msec 64 msec 64 msec

  5 66.192.243.142 [AS 64531] 72 msec 72 msec 72 msec

  6 72.14.212.199 [AS 64531] 72 msec 72 msec 72 msec

  7 209.85.254.130 [AS 64531] 72 msec

    209.85.254.122 [AS 64531] 72 msec

    209.85.254.130 [AS 64531] 96 msec

  8 209.85.254.238 [AS 64531] 72 msec

    72.14.237.130 [AS 64531] 100 msec 72 msec

  9 72.14.238.106 [AS 64531] 100 msec 100 msec

    72.14.232.141 [AS 64531] 116 msec

10 216.239.43.217 [AS 64531] 96 msec

    216.239.46.191 [AS 64531] 96 msec

    216.239.43.217 [AS 64531] 96 msec

11  *  *  *

12  *  *  *

13  *  *  *

14  *  *  *

15  *  *  *

16  *  *  *

17  *  *  *

18  *  *  *

sMc
Hall of Fame Super Silver

Traceroute versus Extended Traceroute

Thanks for the additional information. I believe that it does show us why the behavior was different. By default the Cisco device will use the IP address of the outgoing interface as the source address for the traceroute. In the extended traceroute you specified an IP address for the source address (and I am assuming that it was not the address of the outgoing interface). When the source address was the outgoing interface the traceroute did not work and when the source address was 10.42.21.101 then it did work.

We can not say at this point what causes the regular traceroute to fail, but it could easily be that the specified address is being translated and the outgoing interface address is not. Or it might be a security policy that is denying the address of the outgoing interface.  Or it might be something else.

HTH

Rick

New Member

Traceroute versus Extended Traceroute

Richard

Thank you for the response.

sMc
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