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Debugging and monitoring MPLS networks

Unanswered Question
Oct 8th, 2005
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Hi ,

I've had the following problem with a customer of ours and I'd like to know if there's any tools I can use in the future to better diagnose the problem if it may arise again.

The customer is a bank with hundreds of brnach sites. All of them are connected to the corporate via a MPLS network managed by a local TELCO company .


In the last ten days they have experienced long delays during logons of users in the branch sites . This delay has been initially thought due to new operating systems deployed on the clients ( XP ) . In fact there's a rollout of XP computers at all the branch sites .


Trying to troubleshoot the problem we have started looking at all OS related known problems but found nothing important.


Next I tried looking at the network connections with the few tools I have ( basically ping , traceroute and protocol analyzer ) but all seemed ok .


Having no access to the telco routers I monitored the corporate's switch ports to which the two telco router are attched .

Finally I found some packet discarded and could call the telco and having the routers checked.

They found a problem , they didn't told us what it was , and suddendly most of the problems were gone.


This was really tricky because a part from the slow logon we had no other mulfunctions . I found the problem thanks to a Microsoft tool to check group policy problem which point me to possible networks problem.


The question , after this long post , is ; is there any tool, agent , software I can install or use to check MPLS network efficiency having no access to the TELCO routers ?


Thanks in advance


Stefano Colombo

CCNA - CCSP

MCSE NT/2k/2003 Messaging

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romccallum Mon, 10/10/2005 - 04:43
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havent not told us what the actual problem was it is kinda difficult to suggest tools. However IF this was an MTU issue then you should have used ping with the DF bit set to see how big a packet you could get over the mpls network. Let us know what the issue was and hopefully we can be a bit more detailed in our responses.


HTH

scolombo Mon, 10/10/2005 - 05:22
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The problem we have had was a long logon ( 30-40 minutes ) . We noticed no further problem , apparently.


In one case pinging the DC from the branch site with packets > 1500 Bytes resulted in loss of packets . Thus we have called the ISP



romccallum Mon, 10/10/2005 - 05:51
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yes that is normal practice for mpls networks >1500 with DF set will be dropped. I take it the SP didnt actually tell you what they did to solve your issue? Id quite like to know so that if a customer came to me with the same complaint i would know what was wrong :-)

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