If you're going to get a /20, I'd say get your own from ARIN. The biggest pain of a routing policy I've had to deal with (as far as other people's policies go) is Verio, who only accepts /20 and greater for all of the recently opened legacy class A networks (64., 65., 66 etc) As long as you don't try to slice and dice your /20's into more specific blocks to come out of other places, you'll be fine. Paul -----Original Message----- From: Dan Streufert [mailto:dans@icss.com] Sent: Tuesday, February 20, 2001 1:34 PM To: nanog@merit.edu Subject: Minimum globally routable address space? I am writing from a small, multi-homed ISP. We are contemplating terminating our relationship with one of our providers, and will need to replace that non-portable space. We are debating between getting a /20 from ARIN (we have justifiable usage) or a /20 from our other provider. On one hand, portability would be nice. On the other, is a /20 globally routable in practice? I seem to remember hearing that /19 was the smallest that would not be filtered by anyone. If anyone knows if there are filters for /20s out there, I would be interested to know who filters them. Thanks, Dan Streufert