QoS Design with DSL Networks

[jmujica]

Hi.

I have a design question. I'm in the process to provide QoS in a service provider network in south america for new services that they are going to provide to DSL subscriber like voice and video. They are using ATM as the transport using a pvc for each subscriber. We are evaluating if keeping the pvc at the atm network and doing just IP QoS on that PVC or add two more PVC for a total of 3 to provide some QoS at the ATM level and also doing IP QoS in top of that. The ATM cloud is providing more services not just DSL.

I would like to know which approach are you guys using/recommend?

Thanks in advanced,

-JJ

[lgijssel]

Differentiating on the ATM level is the only viable approach. When you have cell loss on ATM, your IP QoS will not be worth anything.

Regards,

Leo

[Georg Pauwen]

Hello JJ,

I am not really clear on what you are asking: what do you mean by adding two more PVCs to provide some QoS at the ATM level ? Are you talking about adding PVCs just to increase the bandwidth ?

You can always define e.g. service policies under the VC, with one or more PVCs...

If you can, please provide some more detail on what you have in mind...

Regards,

GP

[jmujica]

Hello GP,

I'm looking at how people aproach the end-to-end QoS in DSL networks. About the 3 VCs .... I think that the only way to handle QoS on the ATM is to have 1 VC for each kind of traffic (i.e. voice, data, video) in order for the ATM network to provide Qos at L2. I think that is the best approach.. Right now DSL clients are using just 1 VC and I don't know if adding more VCs will change a lot the configuration (i.e. ip address scheme, etc).

I hope it is more clear now.

-JJ

[Georg Pauwen]

Hello JJ,

ok, understood. I have worked a lot with CBWFQ configurations on ATM PVCs, which lets you define various parameters. In these configurations, all traffic (voice, video, data) was going over one single PVC, and by prioritizing traffic, or by guranteeing a certain amount of bandwidth to e.g. voice traffic, the desired QoS could be achieved.

Have a look at the CCO Technology Page linked below, it contains a couple of sample configs:

IP to ATM Class of Service

Configuration Examples and TechNotes

http://www.cisco.com/en/US/tech/tk39/tk824/tech_configuration_examples_list.html

HTH,

GP

[jmujica]

But with the approach of using just one PVC and doing the IP QoS, if the ATM transport gets congested it will drop any cell including my critical voice traffic. That is what we are debating here.. in doing multiple vc per subscriber (that's it is a lot of work and management on the ATM network) or keep the 1 pvc and provide shaping at L3. IP DSLAM are the way to go but the client has a huge ADSL infrastructure over an ATM network.

Thanks in advanced,

-JJ