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

  • From: David Conrad
  • Date: Mon Oct 08 19:24:33 2007


On Oct 8, 2007, at 2:48 PM, Scott Weeks wrote:
However, if it's less than a /24 it won't get very far as most upstreams block prefixes longer than a /24.

I'm curious: a couple of people have indicated they do not believe this to be the case. Anybody have any hard data on what filters are actually in use today?

Others have indicated that such filters (assuming they exist) will not last in the face of paying customers presenting longer than /24 prefixes for routing. Specifically, that ISPs will relax their filters (allowing longer than /24) in order to get their peers to accept their long prefixes. Anybody have an opinion on the likelihood of this?