"Tactical" /24 announcements

Mon Aug 9 17:38:33 UTC 2021

Folks can announce longer than 24 masks all day. They're unlikely to
propagate very far though, since most won't accept longer than 24 from the
world at large.

To the OP, there are some valid reasons to strategically deaggregate here
and there, but a blanket "yolo my entire allocation into /24s" seems to be
a pretty ill considered request.

On Mon, Aug 9, 2021 at 1:34 PM Hank Nussbacher <hank at interall.co.il> wrote:

> On 09/08/2021 18:47, Billy Croan wrote:
> > How does the community feel about using /24 originations in BGP as a
> > tactical advantage against potential bgp hijackers?
> >
> > All of our allocations are larger and those prefixes we announce for
> > clients as well usually are.  But we had a request recently to
> > originate everything as distinct /24 prefixes, to reduce the effect of
> > a potential bgp hijack.  It seemed a little bit like a tragedy of the
> > commons situation.
> >
> > Is this seen as route table pollution, or a necessary evil in today's
> world?
> > How many routers out there today would be affected if everyone did this?
> > Are there any big networks that drop or penalize announcements like this?
> >
>
> In addition to what everyone else said, announcing /24s will not help
> you one bit since ASNs announce /25s, /26s, /27s, etc. Attached is a
> 7800+ line text file sorted by ASN with prefixes being announced that
> are more specific than /24 (only /25+/26+/27 listed).
>
> This is based on http://www.ris.ripe.net/dumps/riswhoisdump.IPv4.gz from
> about a month ago.
>
> That dump lists all the IPv4 prefixes seen in the collective of latest
> RIS table dumps, together with origin AS and number of peers that passed
> the routes to RIS.
>
> So good luck with announcing /24s.
>
> Regards,
> Hank
>
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