"Tactical" /24 announcements

William Herrin bill at herrin.us
Fri Aug 13 17:29:50 UTC 2021

On Fri, Aug 13, 2021 at 9:49 AM Baldur Norddahl
<baldur.norddahl at gmail.com> wrote:
> Our peer is advertising a prefix for which they will not route
> all addresses covered. Is that route not then a lie? Should
> they not have exploded the prefix so they could avoid covering
> the part of the prefix they will not accept traffic to? (ps: not arguing they should!)

Hi Baldur,

You do understand the consequence of the position you're taking?
You're saying that when an ISP provides a /24 to a customer for
multihoming, a common practice throughout the history of the
commercial Internet, that ISP MUST also disaggregate the announcement
for the supernet that /24 is a part of, exploding the size of the BGP
table. If they don't, the overlapping announcement is a "lie" because
they don't always have a route to the /24.

Bill Herrin

William Herrin
bill at herrin.us

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