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

[Saku Ytti]

On Tue, 2 Oct 2018 at 13:23, Mark Tinka <mark.tinka at seacom.mu> wrote:

> Since we cannot guarantee the end-to-end quality of off-net traffic, it does not make sense to have any DSCP values for Internet traffic other than 0. Because even though I might not remark it, I can't guarantee that my peers, transit providers or other customers won't.

This is not the point here, the point is are you guaranteeing
something with the DSCP. The point is opposite, if you can avoid
caring or acting on them, then you do not need to change them.

Me-Asia ---> Internet ---> Me-Europe

I control my ends PE<=>CE, Me-Europe is often congested and I want to
prioritise SSH interactive sessions there. I could just set SSH to EF
in Me-Asia and have Me-Europe honour it. Internet needs just to pass
the bits, not act on them.

Now of course I can configure stuff so that I break stuff by DSCP
values. But that's not Internet's fault.

> If you are a large network (such as yourselves, Saku) where it's very likely that the majority your customers are talking to each other directly across your backbone, then I could see the case. But when you have customers transiting multiple unique networks before they can talk to each other or to servers, there is really no way you can guarantee that DSCP=1 from source will remain DSCP=1 at destination.

Danish incumbent TDC has ran full pipe for maybe two decades. There is
no way to guarantee what others do, but they view that it's not their
position to mangle other people's traffic, if they can avoid it.

I fully understand that some people technically cannot do short or
full pipe, that's fine. But if you can, I think you should.

-- 
  ++ytti