Re: [GROW] Genart last call review of draft-ietf-grow-bgp-gshut-11

[<[e-mail]>]

Job,

> From: Job Snijders [mailto:[e-mail]]
 > Sent: Tuesday, October 10, 2017 12:06 PM
> 
 > On Tue, Oct 10, 2017 at 09:56:45AM +0000, [e-mail] wrote:
 > > > Minor issues:
 > > >
 > > > In Section 4. "EBGP graceful shutdown procedure", it states that 0
 > > > can used in all cases except where the AS already has a special
 > > > meaning for 0. It seems to me more ought to be said, but I admit I'm
 > > > not well-versed on (I) BGP and might be seeing dragons where only
 > > > windmills are present.
 > >
 > > [Bruno]
 > > I'm not seeing much more to say. It's intended as a warning that an AS
 > > may already use LOCAL_PREF zero to mean something specific. In which
 > > case, the AS knows the specifics,  authors/IETF/draft/RFC do not.
 > > I'm changing to the following reformulation. Please feel free to
 > > suggest text if you prefer.
 > >
 > > OLD: The LOCAL_PREF value must be lower than the one of the alternate
 > > path. 0 being the lowest value, it can be used in all cases, except if
 > > it already has a special meaning within the AS.
 > > NEW: The LOCAL_PREF value SHOULD be lower than the one of the
 > > alternate path. Zero being the lowest value, it MAY be used whichever
 > > LOCAL_PREF values are used by the AS. If LOCAL_PREF zero already has a
 > > special meaning within the AS, and there is a need to distinguish both
 > > usages, another low value MAY be used.
 > 
 > Any attribute (origin, as_path, aggregator) anywhere can be overloaded
 > to mean something only significant to the local network. I think the
 > document is simpler without this and see no point in mentioning this. I
 > propose:
 > 
 > OLD:
 >     The LOCAL_PREF value must be lower than the one of the alternate
 >     path. 0 being the lowest value, it can be used in all cases, except
 >     if it already has a special meaning within the AS.
 > NEW:
 >     The LOCAL_PREF value SHOULD be lower than any of the alternative
 >     paths. It is RECOMMEND to use 0, the lowest LOCAL_PREF value.

What is really needed is "The LOCAL_PREF value SHOULD be lower than the one of the alternative path."
Looks reasonable to extend it to your proposition " The LOCAL_PREF value SHOULD be lower than any of the alternative paths." So I'm changing for this.

Now the value is truly local to an AS, and I'm not sure to see the technical reason to RECOMMEND (SHOULD) a specific value. MAY seems more appropriate to me. Hence I'm proposing to keep
"Zero being the lowest value, it MAY be used whichever LOCAL_PREF values are used by the AS."

I'm open to remove "If LOCAL_PREF zero already has a special meaning within the AS, and there is a need to distinguish both usages, another low value MAY be used." If you believe that this sentence add complexity. I'd agree that it is somewhat redundant, although it does provides a specific point to consider.

 
 > Kind regards,
 > 
 > Job
 > 
 > ps. I-D.ietf-idr-shutdown can reference RFC 8203 now.

Thanks. Fixed.

Kind regards
--Bruno

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