[pim] Re: I-D Action: draft-ietf-pim-multicast-lessons-lea rned-06.txt

I don't think it's that trivial. 

In an N-AS interdomain path AS1...ASN, if every AS plays hot potato,
the unicast packet could only cool off in ASN based on ASN topology - because
all prior AS kept it as hot as they could.

If Unicast AS1->ASN arrive hot, then multicast ASN->AS1
arrives hot. If Unicast AS1->ASN arrives cold, then multicast
ASN->AS1 arrives cold.

"If you're an AS that delivers cold potato unicast,
then you are also an AS that sends chold potato multicast."

Of course, looking at my qualification, i only rank middle of the
road for per capita potato consumption by passports. We'd need an eastern european
or dutch person to chime in here. Although i think the dutch get
up that high only with chips, so they may need to be disqualified for
hot potato expertise.

Cheers
   Toerless

On Sat, Oct 18, 2025 at 09:08:46AM -0400, David R. Oran wrote:
> Thanks - this is a really nice contribution - represents a lot of work and perspective.
> 
> There’s one factor for the multi-domain adoption of multicast that I think was pretty important but wasn’t mentioned:
> 
> Aside from traffic engineering optimizations, ISPs as much as possible do “hot-potato” routing which tries to get the packet off their network as soon as possible. In contrast, multicast turns that on its head and causes “cold-potato” routing where the packet stays on the ISPs network as far as possible before exiting, thus sucking resources.
> 
> DaveO.
> 
> On 17 Oct 2025, at 21:08, [email protected] wrote:
> 
> > Internet-Draft draft-ietf-pim-multicast-lessons-learned-06.txt is now
> > available. It is a work item of the Protocols for IP Multicast (PIM) WG of the
> > IETF.
> >
> >    Title:   Multicast Lessons Learned from Decades of Deployment Experience
> >    Authors: Dino Farinacci
> >             Lenny Giuliano
> >             Mike McBride
> >             Nils Warnke
> >    Name:    draft-ietf-pim-multicast-lessons-learned-06.txt
> >    Pages:   23
> >    Dates:   2025-10-17
> >
> > Abstract:
> >
> >    This document gives a historical perspective about the design and
> >    deployment of multicast routing protocols.  The document describes
> >    the technical challenges discovered from building these protocols.
> >    Even though multicast has enjoyed success of deployment in special
> >    use-cases, this draft discusses what were, and are, the obstacles for
> >    mass deployment across the Internet.  Individuals who are working on
> >    new multicast related protocols will benefit by knowing why certain
> >    older protocols are no longer in use today.
> >
> > The IETF datatracker status page for this Internet-Draft is:
> > https://datatracker.ietf.org/doc/draft-ietf-pim-multicast-lessons-learned/
> >
> > There is also an HTMLized version available at:
> > https://datatracker.ietf.org/doc/html/draft-ietf-pim-multicast-lessons-learned-06
> >
> > A diff from the previous version is available at:
> > https://author-tools.ietf.org/iddiff?url2=draft-ietf-pim-multicast-lessons-learned-06
> >
> > Internet-Drafts are also available by rsync at:
> > rsync.ietf.org::internet-drafts
> >
> >
> > _______________________________________________
> > I-D-Announce mailing list -- [email protected]
> > To unsubscribe send an email to [email protected]
> 
> DaveO

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