Re: [mpls] AD review of draft-ietf-mpls-entropy-label

["Adrian Farrel" <[e-mail]>]

Hi,

Take it as an IETF last call comment (since I already started IETF last call).

Thanks,
Adrian

> -----Original Message-----
> From: Kireeti Kompella [mailto:[e-mail]]
> Sent: 20 August 2012 19:30
> To: [e-mail]
> Cc: Kireeti Kompella; [e-mail];
[e-mail]
> Subject: Re: AD review of draft-ietf-mpls-entropy-label
> 
> On Aug 18, 2012, at 10:18 , Adrian Farrel wrote:
> 
> > Yeah, and it is great that you give a reason for doing it, but by using
SHOULD
> > you have to explain why you might vary. That was what my MAY sentence was
> trying
> > to do. If I got the reason wrong then sorry, please add your own reason.
> 
> Okay.  Proposed text:
> 
>    X MAY choose different values for the TTL and TC fields if it is
>    known that the ELI will not be exposed as the top label at any point
>    along the LSP.
> 
> If this is acceptable, can this wait, or should we spin an -06?
> 
> Kireeti.
> 
> > But if
> > your reason is, because there might turn out to be a reason one day in the
> > future, then use MUST and write a new I-D sometime in the future.
> >
> > A
> >
> >> -----Original Message-----
> >> From: Kireeti Kompella [mailto:[e-mail]]
> >> Sent: 17 August 2012 19:02
> >> To: [e-mail]
> >> Cc: Kireeti Kompella; [e-mail];
> > [e-mail]
> >> Subject: Re: AD review of draft-ietf-mpls-entropy-label
> >>
> >> On Aug 16, 2012, at 23:43 , Adrian Farrel wrote:
> >>
> >>> So...
> >>> OLD
> >>>  X SHOULD put the same TTL and TC fields for the ELI as
> >>>  it does for TL.
> >>> NEW
> >>>  X SHOULD put the same TTL and TC fields for the ELI as
> >>>  it does for TL to protect LSP behavior in cases where PHP is used
> >>>  and the ELI and EL are not stripped at the previous hop (see Section
> >>>  4.4). If it is known that PHP is not used or that PHP will strip the ELI
> >>>  and EL, the TTL and TC of the ELI MAY be set differently.
> >>> END
> >>
> >> X will likely be blissfully unaware of whether PHP will be used (and
whether
> > the
> >> PHP LSR will pop ELI+EL), unless this is a very short LSP.
> >>
> >>> ***or***
> >>>
> >>> s/SHOULD/MUST/
> >>
> >> I have a pathological fear of MUST.
> >>
> >> How about:
> >>
> >> NEW
> >>  X SHOULD put the same TTL and TC fields for the ELI as
> >>  it does for TL.  This protects LSP behavior in cases where PHP is used
> >>  and the ELI and EL are not stripped at the penultimate hop (see Section
> >>  4.4).
> >> END
> >>
> >> I'd better get out a new version before the list of things to do gets any
> > longer.
> >>
> >> Kireeti.=
> >