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New Member

CBWFQ & FRTS problem


Version is :- c2600-is-mz.123-5f.bin

I have a central site with a 2Mb CIR and 21 remote sites. I am trying to implement some FR QoS for voice. I can apply the QoS to my branches but as soon as I apply it to my central site (ie I apply frame-relay traffic-shaping to S0/0) my core app stops responding (this is a simple telnet app).

When I remove the frame-relay traffic-shaping command everything works again.

Any help appreciated & thanks in advance.



Re: CBWFQ & FRTS problem

Hi Paul

You mentioned that had 21 remotes but your config has only got one sub-interface - have you posted the full config of the router ?


New Member

Re: CBWFQ & FRTS problem

Hi Paresh,

This is the full config - it works for all the remote sites (and has done for 2 years!) - the QoS is the problem.



Re: CBWFQ & FRTS problem


there are two points, which are somewhat odd:

First, you use priority queueing for VoIP signaling. This is not recommended, because there is a policer "attached" to the priority command. This means you would drop signaling traffic above 24k, when there is congestion. The recommendation is "bandwidth 24" instead of "priority 24".

This does however not explain your telnet symptoms.

Second, you do not need fragmentation on a 2 Mbit interface. Additionally FR fragmentation has to be turned on on both sides of a PVC. What are the access-link bandwidths of the remote sites?

How do you connect to 21 remote sites? What provider equipment is inbetween your routers? It could be an incompatibility there, especially with FR LMI and fragmentation ...

Regards, Martin

New Member

Re: CBWFQ & FRTS problem

Thanks Martin.

The access rates are 256k from the remote sites - hence the fragmentation.

Also, these are MPLS circuits with FR access to the cloud (BT's IP Clear).

We only have 80k class 1 traffic and the provider only guarantees service for EF traffic - hence marking the signalling to EF. It's 500k class 1 traffic from the hub site.

I was aware of the priority policer but don't see there ever being any more than 24k signalling so was not concerned with prioritising it - I will replace with bandwidth however.

Best wishes,