Problems with AT&T

Wed Mar 19 20:39:10 UTC 2003

If someone can identify what you are actually seeing, I'll check into
it.
If you are experiencing drops or slow traces, only through the core,
there is an issue with excessive de-prioritization of ICMP control
message with a particular router type (vendcor) in the core. End to end
data flow has not seemed to be affected but trace and ping core
latencies are looking very wierd. I've been asking customers to use
trace only for path detail and to use end to end ping for any
performance data. 

Yes, the core is MPLS enabled. Diffserv acted on only at the edges
though. 

Michelle

Michelle Truman   CCIE # 8098
Principal Technical Consultant
AT&T Solutions Center
mailto:mtruman at att.com
VO: 651-998-0949 
w 612-376-5137 

-----Original Message-----
From: brett watson [mailto:brett at the-watsons.org]
Sent: Wednesday, March 19, 2003 1:48 PM
To: nanog at merit.edu
Subject: Re: Problems with AT&T 

On Wednesday, Mar 19, 2003, at 12:28 America/Phoenix, Sean Donelan 
wrote:

>
> On Wed, 19 Mar 2003, German Martinez wrote:
>> Anybody here seeing problems with AS7018 ?
>
> ...
...
>  If you report it to AT&T, they seem to get it fixed; but then
> the problems re-appear a few days later.  I'm guessing that packet
size
> is relevant, but I haven't spent much time trying to troubleshoot it.

isn't at&t heavily MPLSed?  maybe something to do with mpls tunnels, or 
diff-serv marking?