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Old 03-31-2015, 02:27 PM   #1
glennmay
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Registered: Mar 2015
Posts: 2

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Tracepath questions


Hey all,

This is my first post here, so my apologies if I dont happen to give the information someone wants. I'll do my best..

-----

I am working with a network which has some random slowness that we are trying to figure out. Everything on the surface of course appears to be somewhat OK.

One of the commands I am using to track through the network looking for any anomalies is tracepath. So I performed the command on the two hosts in question.

Machine A is the primary, Machine B is the DR.

Machine A to Machine B indicates the following:
[root@MachineA shares]# tracepath 10.13.82.3
1: MachineA.grad-local.domain.com (10.13.81.3) 0.056ms pmtu 1500
1: 10.13.81.1 (10.13.81.1) 2.706ms
1: 10.13.81.1 (10.13.81.1) 2.313ms
2: MachineB.grad-local.domain.com (10.13.82.3) 0.282ms reached
Resume: pmtu 1500 hops 2 back 63


Machine B to Machine A indicates the following:
[root@MachineB shares]# tracepath 10.13.81.3
1: MachineB.grad-local.domain.com (10.13.82.3) 0.074ms pmtu 1500
1: 10.13.82.1 (10.13.82.1) 2.320ms
1: 10.13.82.1 (10.13.82.1) 2.304ms
2: MachineA.grad-local.domain.com (10.13.81.3) 0.374ms reached
Resume: pmtu 1500 hops 2 back 63


So my question is this. It is showing 2 hops (The 82.1 and 81.1 router are the same machine which is a Procurve) But the back hops are showing as 63..

Not sure what that indicates, or means. But it seems very far out of scope given the network configuration.


I admit this is not my network and I am working on this for someone else. So the possibility that I am not 100 privvy to the network infrastructure is realistic. But is there a way I can get a look into where those packets are traveling back from to see whats what?

Thanks in advance.


Glenn

** Naturally the names and identities of all have been changed **
 
Old 03-31-2015, 04:18 PM   #2
zurron
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Registered: Feb 2003
Location: Pereira
Distribution: slackware
Posts: 23

Rep: Reputation: 15
Hi

if you are trying to find the reason for a slow network try first to mesuare the response of the switches and router interfaces, try to SNMP to monitor bandwith and process load, it is also use tools as iperf, nethogs and finally I prefer traceroute instead of tracepath
 
Old 04-01-2015, 09:42 AM   #3
glennmay
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Registered: Mar 2015
Posts: 2

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I have somewhat limited ability to run tools on this network. It is not mine to do as I wish and there are security concerns with running anything that walks the network.


If anyone has any ideas for a good way to figure out why I am seeing such a variant in the return path as I am the forward, that is where I am concerned right now.


Thanks
Glenn
 
Old 04-01-2015, 05:17 PM   #4
MikeDeltaBrown
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Registered: Apr 2013
Location: Arlington, WA
Distribution: Slackware
Posts: 96

Rep: Reputation: 10
I would check for dropped packets with `ping`. It looks like the return path has problems. Could be something as simple as a bad cable. If one wire on the transmit pair (100Base-T) is open you could see something like this.
 
  


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