[nsp] ATM questions

Aaron Howell aaronh at amerion.net
Wed Aug 20 11:06:41 EDT 2003

We've recently moved to ATM circuits in a few locations where we
previously had serial DS3 or T1 connections, and we're seeing some
problems.  Basically after about 12 hours or so the latency on the
circuit goes insane, from 400 to 1000 ms.  The router doesn't show any
increase in CPU usage, or memory, it doesn't crash if you leave it go,
it just continues to ping high.  The telco is saying everything is clean
on their end, and there's absolutely no problem, they also say my config
looks good.  We're having this problem in two geographically separate
locations, (SD and AZ), on two different platforms, (3640 and 7513),
with two different IOS versions, but the EXACT same symptoms.  I'm not
ruling out my config being wrong, as I'm new to the ATM game.  It seems
to me that when the latency goes nuts the output drops have increased
dramatically, and the weird thing about that is that it's generally at
low traffic times, late in the evening, or early in the morning.  Config
from the 7513 is included below, if anybody has any ideas I would
appreciate some feedback.

interface ATM5/0/0
 description Qwest DS3
 no ip address
 no ip mroute-cache
 atm scrambling cell-payload
 atm framing cbitplcp
 no atm ilmi-keepalive
interface ATM5/0/0.1 point-to-point
 description Qwest DIA  VPI:2 VCI:34  9MB
 ip address xx.xxx.xxx.xx
 ip access-group atm5/0/0.1in in
 ip access-group atm5/0/0.1out out
 pvc 2/34
  abr 9000 1500
  encapsulation aal5snap
  transmit-priority 1

Aaron Howell
Network/System Administrator
Amerion, LLC

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