Re: Use cases for PMTUD and PLPMTUD (was: RE: 6MAN: Adoption call on draft-hinden-6man-rfc1981bis-01)

[Bob Hinden <[e-mail]>]

Fred,

> On Feb 5, 2016, at 10:13 AM, Templin, Fred L <[e-mail]> wrote:
> 
> Starting this under a new thread, IMHO if we want to promote RFC1981 to standard
> we should understand its use cases as well as the use cases for RFC4821.

Sorry for being argumentative, but this is not a requirement to move RFC1981 to Internet Standard.  It’s already at Draft Standard.  See RFC6410.

Instead continuing the debate over how RFC4821 should be cited in rfc1981bis, I am starting to think that a separate new document could discuss the relationship between the two approaches to learning the MTU, and make some recommendations on how they should be used together or separately.  Perhaps a BCP or update to Node Requirements.

I don’t think this topic needs to be part of advancing RFC1981.

Bob

> 
> First, it is reasonable to expect that paths that begin and end within the same
> well-managed administrative domain can be counted on to deliver the necessary
> ICMPs. An example is my employer's corporate network. In that case, traditional
> PMTUD per RFC1981(bis) can be applied alone w/o having to apply RFC4821.
> 
> On the other hand, paths that lead to Internet destinations cannot be counted
> on to deliver the necessary ICMPs. In that case, RFC4821 provides a mitigation.
> 
> But, if we do not believe that there are paths for which traditional PMTUD
> can still be used safely, then we should be working to deprecate RFC1981
> instead of making it a standard.
> 
> Thanks - Fred
> [e-mail]
>