"Tactical" /24 announcements

Lukas Tribus lukas at ltri.eu
Wed Aug 11 12:05:13 UTC 2021

On Wed, 11 Aug 2021 at 12:24, Tom Hill <tom at ninjabadger.net> wrote:
> On 10/08/2021 07:15, Lukas Tribus wrote:
> >> Are there any big networks that drop or penalize announcements like this?
> > It's possible you could get your peering request denied for this. I
> > have put *reasonable* prefix aggregation into peering requirements for
> > some years now. If you are a small eyeball network with 8192 IP
> > addresses and originate 32 /24's, that is *not* reasonable.
> It is quite an issue when a network tries to programmatically filter-out
> the /24 more-specifics advertisements made from an allocated, .e.g, /20.
> Such anti-disaggregation/save-my-TCAM efforts really do not work, and
> will spawn all manner of support tickets. I'm saying this in the hope
> that it may prevent someone from reading this thread and concluding that
> it may be a good idea to try. It is not.

For the record: I did not suggest anything like this.

Denying peering requests due to lack of *reasonable* prefix
aggregation does not mean installing fancy, impossibile to maintain
prefix-lists on transit ingress. I agree with you here, that would be
very bad.

This save-my-TCAM effort is successful when the peer on the other site
actually realizes that there are consequences to decisions like this
and reverts it, which is a long shot, sure, but at least I'm not
encouraging this. I don't get to dictate other peoples configurations.
I do get to decide who is directly exchanging traffic with my network
and who isn't.


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