Re: [mpls] [Tsvwg] multiple-working group last call on draft-ietf-mpls-cosfield-def-04.txt

[John Kenney <johnkenney at alumni.nd.edu>]

Hi Loa,

This is a good draft.  It's time to rename the EXP field.  While CoS 
Field may have been a good choice at one time, we've now heard from many 
who think it is too narrow for current usage of this field.

I suggest "Traffic Management Field".

Traffic management is a common, generic, and concise term.  It covers 
all current uses of the field: scheduling class, drop priority, and 
congestion notification. CoS really only covers the first.  Traffic 
management is well-scoped to this purpose, and clearly preferable to CoS 
in my opinion.

In terms of the draft, I think a simple global substitution of "traffic 
management" for "class of service" and of "TM" for "CoS" should suffice.

I think in the long run we'll be glad if we bite the bullet now and make 
this change.

Best Regards,
John


Loa Andersson wrote:
> Bob,
>
> thanks for useful comments :)
>
> Bob Briscoe wrote:
> > Loa,
> >
> > I believe this draft has no technical effect. However there is some 
> > truth in the idea that names are important.
> >
> > So, let's set aside a few clock cycles to consider this...
> >
> > 1/ Is CoS a good description of ECN? Given RFC5129 (Using the EXP 
> > field for ECN in MPLS), is it really appropriate now to call this a 
> > CoS field?
> >
> > Thinking out loud...
> > - CoS is a signal from an ingress to the interior (a request for a 
> > certain class of service),
> > - whereas ECN is a signal from the interior forwarding plane to the 
> > egress (a response from the interior saying whether the class of 
> > service requested was congested).
> >
> > The way 5129 was done, two (or more) EXP codepoints can be designated 
> > as the same CoS, but one can be used to say "this packet experienced 
> > congestion when using this CoS", while the other says "it didn't". 
> > So, I guess I could live with this field being called CoS, even 
> > though it's not strictly correct. I can't think of anything better.
>
> We had the same discussion when we started to discuss this draft, we
> wanted to find a name the covered both cases. We just couldn't come
> with a better name, so we said "Let us call it 'CoS Field'" and change
> it someone comes up with something better.
>
> I'm still open to do that change, but time is kind of running out, the
> latest point in time we can do this change is an RFC editor note, when
> the IESG has approved the document.