Traceroute completed after 3 replies from host

[muca]

Hi, does anyone know any reason for tracert to be completed only after 3 response times from the host?

1 <1 ms <1 ms <1 ms 172.18.0.1

2 <1 ms <1 ms <1 ms 172.30.255.14

3 <1 ms <1 ms <1 ms 172.30.255.1

4 <1 ms<1 ms <1 ms 172.30.0.13

5 <1 ms<1 ms 2 ms 202.x.x.x

6 * * * Request timed out.

7 1 ms 1 ms 1 ms 172.29.51.141

8 1 ms 1 ms 1 ms 172.29.51.141

9 1 ms 2 ms 1 ms 172.29.51.141

Trace complete

[royalblues]

Whenever you do a trace you send 3 probes and hence you see 3 responses

HTH

Narayan

[muca]

What I mean is:

7 1 ms 1 ms 1 ms 172.29.51.141

8 1 ms 1 ms 1 ms 172.29.51.141

9 1 ms 2 ms 1 ms 172.29.51.141

[bvsnarayana03]

What Narayan said is true. But your question is also valid. I've seen it many a times with destination repeating itself. What i found is there might be multiple paths to reach the destination. In your case 3 paths.

hope that clarifies.

pls rate all helpful posts.

[smothuku]

Hi ,

The router will send 3 traceroute packets with TTL of 1 and will know the next hop because the next hop returns the TTL exceeded message. It will then send 3 traceroute packets with TTL of 2, and so on sending 3 packets each time that it increases the TTL until it reaches the destination.

Because of 3 trace packets you are seeing same ip repeating thrice..

Thanks,

satish

[mohammedmahmoud]

Hi,

I think Narayan and Satish have covered you question, just as a reference, please check the following document:

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

HTH,

Mohammed Mahmoud.

[anthonykahwati]

I know this post is from 2007, but I never knew this and have been in networking a long time.... nice to learn something new about networking 101!

[mheusing]

Hi,

The interesting entry is: 6 * * *

This usually is because of a firewall or other secured device. A definite answer could only be given by the administrator of the firewall.

The most likely explanation for me is, that this firewall or secured router performs NAT/PAT, i.e. translates internal addresses into 172.29.51.141 where "internal" is from the viewpoint of the firewall.

Thus you might have two routers (7 + 8) and the internal host (9) with different internal addresses all being translated to the same IP by the firewall/secured router.

Hope this helps! Please rate all posts.

Regards, Martin

[mohammedmahmoud]

Hi Martin,

Perfect explanation.

Murilo, can you please confirm.

BR,

Mohammed Mahmoud.

[muca]

Two pix. However the firewall administrator of the 1st pix is not performing any NAT/PAT but definitely on the other end we have NAT.