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

[Saku Ytti]

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.

> 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.



-- 
  ++ytti