MPLS QoS from a customer point of view

[atef yamin]

Hi all,

We are about to implement MPLS between our sites and one of the topics under discussion is QoS. Are there any MPLS-Specific configurations on the customer side ? Would a simple DSCP marking work? based on my understanding so far the EXP bits are read from the DSCP bits. so is setting the DSCP bits enough on a customer side?

Regards

[Giuseppe Larosa]

Hello Atef,

>> so is setting the DSCP bits enough on a customer side?

your understanding is correct, whatever marking is used is MPLS SP network the customer is required to mark its own IP traffic with DSCP settings using values  per agreed SLA.

You should also shape your traffic to be within the rates.

Hope to help

Giuseppe

[milan.kulik]

Hi Giuseppe,

I had an interesting discussion with an MPLS provider  recenlty regarding the QoS settings on CE and PE sides.

My understanding is there should be exactly the same bandwidth assigned to particular QoS Classes on both sides.

But the provider seems not to configure the PE routers this way.

What's your opinion?

Thanks,

Milan

[Giuseppe Larosa]

Hello Milan,

from the MPLS SP point of view it is a question of what QoS model they want to apply.

The simplest model is to define the SLA per VRF site / access link and in this case I would expect symmetric definitions of bandwidth for all the QoS classes. (point to point model)

However, other QoS models are possible, because the MPLS L3 VPN is point to multipoint in nature, the MPLS SP may want to differentiate what is received from the VRF site from what is sent to the VRF site, that can potentially be originated at multiple remote VRF sites.

If this is the case the bandwidth settings for the QoS classes might be different in the two directions from VRF site to backbone and from backbone to VRF site. (point to cloud ak.a. hose model)

see

http://www.cisco.com/en/US/tech/tk436/tk428/technologies_white_paper09186a00800a4455.shtml#wp26748

Hope to help

Giuseppe