North American Network Operators Group

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Re: Upstreams blocking /24s? (was Re: How Not to Multihome)

  • From: Justin M. Streiner
  • Date: Mon Oct 08 21:35:46 2007

On Mon, 8 Oct 2007, Jon Lewis wrote:

 adopted /24 as the cutoff point.  If you make the cutoff point smaller,
 what is the new point... /26?  /32?

Anything longer than /24 is unlikely to propogate far on the internet. You can all check your filters to see. I just checked mine, and neither Level3 nor Time Warner has tried to send me anything longer than /24 in recent history. If they did, it'd show up as hits on a distribute-list deny rule.

I realize that - I was posing a rhetorical question to the previous poster :)

This is actually in the ARIN "rules". Multihoming is justification (regardless of utilization) for one of the multihomed network's providers to assign them a /24.

Been down that road a few times too, both as a provider and a customer.