[cisco-bba] Problems with CBWFQ, 12.3T and adsl 800 routers

[Félix Izquierdo]

Hi,

I've found a serious problem using a simple CBWFQ policy on atm 
subinterfaces/pvc for 826/827/836/837 ADSL routers running various 
releases of 12.3T ( the same problem was found in 12.3(4)T7, 12.3(7)T2 
and all the rebuilds of 12.3(8)T ).

This is the config used to get WFQ on adsl interfaces:

policy-map adsl-wfq
  class class-default
   fair-queue

interface ATM0
  no ip address
  no atm auto-configuration
  no atm ilmi-keepalive
  no atm address-registration
  no atm ilmi-enable
  bundle-enable
  dsl operating-mode auto
!
interface ATM0.1 point-to-point
  ip unnumbered Loopback0
  pvc 1/32
   tx-ring-limit 3
   oam-pvc manage
   encapsulation aal5mux ip
   service-policy output adsl-wfq
  !
!

The problem is that many times interface atm0.1 stops to output IP 
packets ( but not OAM cells ) and all the packets are droped and/or 
queued forever in the CBWFQ queues. Only "clear inter atm 0" recovers 
the router. The same problem if the encapsulation is PPPoA, but then the 
router stops to send not ip, but the PPP frames encapsulated in aal5.

Any similar experiences?

Thanks.

Félix