sh ip route 16.11.4.71

Routing entry for 16.11.4.0/24

Known via "eigrp 4", distance 90, metric 76800, type internal

Redistributing via eigrp 4

Last update from 16.12.1.251 on Vlan1, 03:18:33 ago

Routing Descriptor Blocks:

16.12.1.252, from 16.12.1.252, 03:18:33 ago, via Vlan1

Route metric is 76800, traffic share count is 1

Total delay is 500 microseconds, minimum bandwidth is 40000 Kbit

Reliability 255/255, minimum MTU 1500 bytes

Loading 4/255, Hops 4

* 16.12.1.251, from 16.12.1.251, 03:18:33 ago, via Vlan1

Route metric is 76800, traffic share count is 1

Total delay is 500 microseconds, minimum bandwidth is 40000 Kbit

Reliability 255/255, minimum MTU 1500 bytes

Loading 94/255, Hops 4

Sorry..left out another question of yours..yup, i am using EIGRP only..for routing..

Cindy

The results that you see reflect the fact that the router has 2 paths in the routing table toward that destination and is load sharing its packets over both connections.

It may help to review some basics of traceroute as implemented by Cisco. 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.

So in looking at your output each line represents one of those traceroute packets.

this is the 1 of 3 with TTL of 1

1 16.12.1.251 0 msec

and this is 2 of 3 with TTL of 1

16.12.1.252 0 msec

and this is 3 of 3 with TTL of 1

16.12.1.251 0 msec

and this is 1 of 3 with TTL of 2

2 16.12.254.254 9 msec

and this is 2 of 3 with TTL of 2

16.12.254.250 0 msec

and this is 3 of 3 with TTL of 2

16.12.254.254 0 msec

and this is 1 of 3 with TTL of 3

3 16.11.254.25 9 msec

and this is 2 of 3 with TTL of 3

16.11.254.45 0 msec

and this is 3 of 3 with TTL of 3

16.11.254.25 8 msec

and this is 1 of 3 with TTL of 4

4 16.11.19.1 9 msec

and this is 2 of 3 with TTL of 4

16.11.19.2 16 msec

and this is 3 of 3 with TTL of 4

16.11.19.1 9 msec

and at TTL of 5 all packets get to the destination.

5 16.11.4.71 8 msec 9 msec 8 msec

HTH

Rick

Rick,

What I dont get it is are they really routing to that router or this is just purely informative ?

eg:

this is the 1 of 3 with TTL of 1

1 16.12.1.251 0 msec

and this is 2 of 3 with TTL of 1

16.12.1.252 0 msec

and this is 3 of 3 with TTL of 1

16.12.1.251 0 msec

So, is this means that TTL of 1, the routing travel to 16.12.1.251 -> 16.12.1.252 -> then back to -> 16.12.1.251 , or it goes straight to 16.12.1.251, and the info above is purely information?

Thanks.

Cindy

I am not sure that I completely understand your question. Let me explain what I think it is about and if I do not get it quite right then maybe you can clarify for me.

At each TTL the router sends 3 packets. So:

this is the 1 of 3 with TTL of 1

1 16.12.1.251 0 msec

was the first packet. It was sent to 16.12.1.251 and that router reduced TTL which expires the packet and sent a response to your router. And then your router generated the next packet:

and this is 2 of 3 with TTL of 1

16.12.1.252 0 msec

and it was sent from your router (also with TTL of 1) and went to 16.12.1.252 and that router reduced TTL which expires the packet and sent your router a response. And then your router generated the next packet:

and this is 3 of 3 with TTL of 1

16.12.1.251 0 msec

is the third (and last) with TTL of 1. It was sent to 16.12.1.251 and that router reduced TTL which expires the packet and sent a response to your router.

And then the same things happened with TTL of 2. Your router sent each of the 3 packets with TTL of 2. Each packet got to the second hop router and timed out and sent a response to your router.

It might help your understanding if you do show ip route for the destination that you are doing the traceroute to. I am sure that your routing table has 2 entries and the first entry has next hop of 16.12.1.251 and the second entry has next hop of 16.2.1.252.

If that does not get the point of your question then please try again.

HTH

Rick

Rick,Thanks. About that.. but

Actually I am trying to understand why there are 3 packets instead of 2 packets as there are 2 entries that this route can go..

Yup, you are right.I have checked sh ip route and there are 2 entries that this route can go to.

Cindy

Your question suggests that you assume that there would be 1 packet per path. While that might be a logical thing to do, that is not the way that Cisco (and others) implement traceroute. In the Cisco implementation of traceroute there are 3 packets generated at each TTL no matter how many paths.

HTH

Rick