Drops of ATM cells on the ATM ISP side, even if we “shaping”.

[psinisalo]

We have one 7200 with c7200-is-mz.120-20.bin and ATM WAN OC3 (SMI) port adapter, 1 port.

The problems is that even if I can see that our “shaping” drops packets OutPktDrops: 197.

Our ISP tells us we are sending traffic above PCR and therefore drops ATM cells.

They are using Nortell passport equipment and they have told me is a known IOS “bug”.

I only found older “bug” for IOS 11.0.

Have you any proposal ?

/regards Per Sinisalo

interface ATM2/0

mtu 1500

no ip address

no ip directed-broadcast

logging event subif-link-status

atm sonet stm-1

no atm ilmi-keepalive

!

interface ATM2/0.1 multipoint

bandwidth 2752

ip address 172.28.250.5 255.255.255.0

no ip directed-broadcast

ip split-horizon

pvc r-6102 0/249

class-vc CIR128

!

vc-class atm CIR128

inarp 1

broadcast

vbr-nrt 280 280 1

oam-pvc manage

oam retry 3 5 1

encapsulation aal5snap

[cventicinque]

Sounds like a possible CDVT issue? Also, make sure you are talking the same numbers with your ATM provider (ie what is 1K? 1000 or 1024?)

[psinisalo]

If it is this kind of problem, is there something I can chance in my configuration to solve it ?

[zsiddiqu]

First find out what is the exact PCR and SCR from your telco in kbps (not cells/sec). Currently you have configured both the PCR and SCR to 280kbps. If you are exceeding the telco restricted bandwith then change your vbr-nrt statement in the configuration to reflect the true numbers for PCR and SCR.