[j-nsp] Use cases for IntServ in MPLS backbones

[Mark Tinka]

On 2/Oct/18 10:21, James Bensley wrote:

> Yeah so not already using RSVP means that we're not going to deploy it
> just to deploy an IntServ QoS model. We also use DSCP and scrub it off
> of dirty Internet packets.
>
> Like with many things, it depends on your requirements. Having worked
> for managed WAN providers where you have a infrastructure shared
> amongst multiple customers / stakeholders and provide WAN connectivity
> with over the top services like Internet and VoIP, QoS is a product
> most customers expect. In this scenario you typically have a set of
> queues and customer can access either all of them or a sub-set for a
> cost. In a former life we had up-to 8 classes for customers which you
> can simplify in your core using pipe mode or short pipe QoS models. We
> could offer multiple QoS levels to customers, but simplify the classes
> down to like 3-4 in the core, and without any need for RSVP. I feel
> this is a good balance between complexity/simplicity and scalability.
> If you don't have multiple stakeholders then IntServ becomes more
> appealing due to the granularity on offer, but in the shared
> infrastructure scenario my experience is that mapping multiple
> customer queues down to a fewer core queues helps to protect the
> control plane and LLQ traffic in a simply way that covered all stake
> holders, and no need for the additional signalling complexity that
> RSVP brings.

I've never quite understood it when customers ask for 8 or even 16
classes. When it comes down to it, I've not been able to distill the
queues to more than 3. Simply put, High, Medium and Low. The 4th queue
is for the network itself.

As you said, you can give a customer 100 classes, but in the backbone,
they'll likely fall into just these 3 queues.

We run 3 queues, and also tell customers that we can only offer 3 classes.

All Internet traffic is in the "Low" queue. Depending on the type of
on-net VPN service you're buying from us, you'll either end up in the
"Medium" or "High" queue. This is enforced across all devices, right
from the access, edge, core and the same on the other side.

Mark.