Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

  • Congratulations Mike Lewis on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!

IP packet loss on ATM OC3

Status
Not open for further replies.

JimboNJ

ISP
Sep 5, 2008
3
0
0
US
Hey all,

Got a problem I can't figure out. We've got an ATM OC3 connection into the local ILEC's cloud with a bunch of PVCs built to customers. Just about every single customer on this OC3 is having bandwidth problems and problems with packet loss.

If we do a ping via IP across the PVC with any packets larger than 500 bytes, we see anywhere between 3% and 10% packet loss. This does not happen with our ATM DS3s in the same router. There aren't any interface errors accumulating, and the ILEC has tested the circuit clean to a loop in our router. If we do end-to-end OAM echos on each PVC everything turns up fine with no cell loss. I'm really at a loss as to what the problem could be, but basically the ILEC is telling us we must have a problem with our Cisco config.

Non-working ATM OC3 sample config:
interface ATM1/1/0
bandwidth 155000
no ip address
load-interval 30
atm ilmi-keepalive

Sample of PVC config from non working OC3:
interface ATM1/1/0.4 point-to-point
bandwidth 20000
ip address x.x.x.x 255.255.255.252
pvc 1/103
ubr 20000
encapsulation aal5snap
!

Ping results from the router:
Sending 50, 1000-byte ICMP Echos to x.x.x.x, timeout is 2 seconds:
!!!!!!!!!!.!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 96 percent (48/50), round-trip min/avg/max = 1/2/4 ms

Sample config of working ATM DS3 in same chassis:
interface ATM4/1/0
bandwidth 45000
no ip address
load-interval 30
atm scrambling cell-payload
no atm ilmi-keepalive

Sample of PVC from working DS3:
interface ATM4/1/0.12 point-to-point
ip address x.x.x.x 255.255.255.252
pvc 1/53
ubr 44000
encapsulation aal5snap
!

Ping results:
Sending 50, 1000-byte ICMP Echos to x.x.x.x, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (50/50), round-trip min/avg/max = 4/4/8 ms


I'd be very appreciative of any troubleshooting suggestions anyone may have.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top