Loss of IP connectivity due to Qos on ATM PVC

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Mar 30th, 2010
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Hi all,

I have a 2921 series router w 15.1M series IOS. The platform has HWIC-2SHDSL module installed, which is used for point-to-point G.SHDSL connectivity. When I apply a service-policy on atm pvc, after 10 to 20 minutes I lose IP connectivity on ATM interface and tunnel interface also goes to down state. If I remove the service policy on ATM PVC IP connectivty returns back.

Interestingly I use exactly the same config on 2821 platform (w. WIC-1SHDSL installed) and I do not live such an issue on that platform.

I tried to carry the Qos config on to Tunnel interface with shaping enabled and "no qos-preclassify" command issued, but the result is the same.

What may be the cause of that issue?

policy-map MetroDSL-llq

class sna-dsl

    bandwidth percent 10

class netbios-dsl

    bandwidth percent 10

class class-default



interface ATM0/0/0.1 point-to-point

ip address x.x.x.x

no snmp trap link-status

atm route-bridged ip

pvc 0/35

  vbr-nrt 1024 1024

  encapsulation aal5snap

  service-policy output MetroDSL-llq

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Giuseppe Larosa Sat, 04/03/2010 - 01:42
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Hello Selman,

I would suggest to open a Service Request for this issue with TAC.

From the information you have provided you have probably hit a SW defect on the newer router

Hope to help


samuelabad Thu, 07/28/2011 - 13:22
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I have the same issue. I want to know if you solved this problem. I have a case in the TAC, but I have not had the solution.

serhat.selman Thu, 08/25/2011 - 01:34
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Hi Samuel,

Yes we solved it

In our case, there was a compatibility issue with HWIC series G.SHDSL cards and ATM DLSAMs in which our ISP uses.

We solved our issue by carrying the the DSLAM ports to another vendors devices, and also to IP DSLAMs.

Hope it helps.


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