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

[Julien Goodwin]

On 02/10/18 20:26, Saku Ytti wrote:
> On Tue, 2 Oct 2018 at 13:21, Julien Goodwin <jgoodwin at studio442.com.au> wrote:
> 
>> The trouble is, some providers might use a bit to mean something like
>> "prefer cheap EU paths" for Asia->AU traffic, leaving it set then causes
>> hundreds of milliseconds of latency. Some might even implement VPNs that
>> way causing blackholing.
> 
> I don't think so, If they use DSCP values as-is, then they MUST
> nullify them. Full and short pipe assume you use MPLS TC for internal
> decision, at which point you don't need to care or trust DSCP. If you
> use DSCP internally _AND_ trust Internet DSCP, it's broken
> configuration.

... and since when would *any* network ever have a subtly broken config?

Except for, you know, pretty much every network in practice.

>> We had a few cases where failing to set DSCP to zero at our edge (in
>> either direction) caused various issues, those also took weeks to
>> troubleshoot.
> 
> It is indeed possible to misconfig things. But it's not the problem of
> instance sending DSCP, it's problem of the instance having broken
> config based on DSCP.
> 
> 
>