Don't know for certain, but I announce from time-time singular /24s out of my 64.x block (without announcing entire block, although at times I'd announce entire block as two /20s well) and have seen no problems with verio or anybody else. On Wed, 15 Oct 2003, Jean-Christophe Smith wrote:

I noticed the verio filter policy, in relation to inbound: - In the traditional Class A space (i.e., 0/1), we accept /22 and shorter.

If I want to announce a /24 in the 64.x.x.x space(traditional Class A space) am I'm going to have a problem with other networks that have peer filters similar to Verios?

Thanks, Jean-Christophe Smith

-----Original Message----- From: Phil Rosenthal [mailto:pr@isprime.com] Sent: Wednesday, October 15, 2003 1:47 PM To: John Palmer Cc: nanog@merit.edu Subject: Re: Pitfalls of annoucing /24s

http://info.us.bb.verio.net/routing.html#PeerFilter

That's how Verio does it, and I assume, that's how most people who filter by length do it as well.

--Phil On Oct 15, 2003, at 4:40 PM, John Palmer wrote:

...

Good question.

You know there are thousands of legacy /24's out there that were allocated by IANA as /24's How can you aggregate them up if all you have is the /24?

To those who filter out /24's - how is this done - just by the netmask size?

----- Original Message ----- From: "Jean-Christophe Smith" <jsmith@vitalstream.com> To: <nanog@merit.edu> Sent: Wednesday, October 15, 2003 15:34 Subject: Pitfalls of annoucing /24s

...

In current practice would there be serious jeopardy of portions of the internet not being able to reach this address space due to bgp filters or other restrictions? What is the smallest acceptable block of IPs that can be announced without adverse or unpredictable results? Verio would most likely be picking up these routes from us. I don't want to cause a religious debate, but I am interested in what the industry consensus is.

I'm just doing some research, any comments would be appreciated.

Thanks, Jean-Christophe Smith

--Phil Rosenthal ISPrime, Inc.