Re: [v6ops] [EXTERNAL] Re: draft-ietf-6man-grand : saving lookups

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Tue, 11 August 2020 14:55 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: Bob Hinden <bob.hinden@gmail.com>, Nick Hilliard <nick@foobar.org>
CC: IPv6 List <ipv6@ietf.org>, "v6ops@ietf.org" <v6ops@ietf.org>
Thread-Topic: [EXTERNAL] Re: [v6ops] draft-ietf-6man-grand : saving lookups
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Date: Tue, 11 Aug 2020 14:54:50 +0000
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Subject: Re: [v6ops] [EXTERNAL] Re: draft-ietf-6man-grand : saving lookups
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Hi Bob,

> > Maybe we need an ID which states this explicitly: "Large broadcast domains considered harmful"?  As long as we have broadcast
> domains, people will be tempted to make them too large and will express surprise that they don't scale well.
> 
> I agree on both points.   I would be willing to help write such a draft, but think it would be better with authors who have direct
> operational experience.

Some NBMA links can be *very* large, with all nodes on the link as candidates for receiving
link-scoped multicast. However, with proper controls on limiting the transmission of link
scoped multicast, the transmissions can be effectively propagated to exactly that (small)
group of nodes on the link that actually need to receive them. So, if there is going to be a
draft please make sure to add a note to the effect that properly engineered NBMA links
are an exception, and can in fact support a very large broadcast domain.

Thanks - Fred

> 
> Bob