[c-nsp] strange behavior over MPLS network - remote desktop won't work

Chris Phillips cphillips at wbsconnect.com
Sun May 31 16:20:31 EDT 2009

A shot in the dark here, but what's the MTU along the path?

I know things like Outlook Web Access won't work unless there's a 
minimum 1500 MTU.

I highly recommend grabbing MTUroute.exe and testing this.


Chris Hale wrote:
> All -
> We have a simple three node MPLS network that we've deployed for a customer
> across our backbone.  Two sites connect to POP "N" and one site connects to
> POP "H".  We have CE (Juniper J2320's) that provide OSPF updates to the PE
> for customer routes, and Internet is also provided via a second circuit to
> the site off POP "H".
> Site W and Site S are off POP N.
> Site B is off POP H.
> POP N and POP H are connected directly to each other via GigE over wireless
> backhaul.  Sites W, S, and B are connected to POPs via wireless bridges and
> use 802.1q trunks to aggregate traffic to the core routers.
> Here is a simple ASCII text:
> Site W
>    |
> cisco 7206 (POP-N) ->---wireless backhaul gige ---->-cisco-7206
> (POP-H)--->fastE--->cisco7206(POP-H)--->---Site B ----> Cisco ASA --->
> Internet
>    |
> Site S
> All CE routers pick up the routes from the other CE routers, and ICMP works
> fine throughout network. Users in Sites W & S can access Internet.
> Users between Site W and Site S can use remote desktop/VNC to access other
> desktops/servers within these sites (i.e. between Site S and Site W, remote
> desktop is fine).
> The issue is when users in Site B try to remote desktop into Site W or Site
> S, or either Site W or S go to Site B.  Again, site S<-->W is fine.
> I have packet captures with and without the CE routers, and I see traffic
> going back and forth between W and B for a test on TCP 3389.  Again, pings
> and other traffic work fine between these sites, it just seems to be remote
> desktop or VNC.  The customer can get the login window to pop up but then it
> seems to hang after a few seconds.
> They are migrating off a p2p T1 connect between W<---->B<---->S, and they
> used plain 1600 series routers.  Remote desktop/VNC worked fine before
> migrating to our MPLS connections.
> Thanks,
> Chris
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Chris Phillips

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