[179253] in North American Network Operators' Group
Re: Small IX IP Blocks
daemon@ATHENA.MIT.EDU (Bill Woodcock)
Sat Apr 4 22:36:58 2015
X-Original-To: nanog@nanog.org
From: Bill Woodcock <woody@pch.net>
In-Reply-To: <CALB2hAcs0E_7M2AiD4=tYsw-UNmJtDMx9g7xzioRzgOaPZm9hQ@mail.gmail.com>
Date: Sat, 4 Apr 2015 19:36:17 -0700
To: Mike Hammett <nanog@ics-il.net>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
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> On Apr 4, 2015, at 7:28 PM, Charles Gucker <cgucker@onesc.net> wrote:
>=20
> I've been involved in IX renumbering efforts because exchange(s)
> decided to use /25's instead of /24's. It's painful because
> troubleshooting can be a little difficult as differing subnetmasks are
> in play. If you have the address space, use a /24. ARIN has IPv4
> address space specifically reserved for the use by IXPs.
Yes. Listen to Charlie.
We did a bunch of analysis on size of IXP subnets, and how it changes =
over time, relative to the age of the IXP. To summarize drastically, =
the first /24 typically lasts about 15-18 years. Only a tiny handful of =
exchanges (less than 2%) are actually supporting more than 254 =
participants yet at this point. That number will continue to grow over =
time. At the same time, it=92s not worth the trouble of renumbering =
more than once in that time period, so don=92t be penny-wise and =
pound-foolish by trying to use a /25, particularly when ARIN hands out =
/24s to IXPs specifically to keep them from running into that trap.
-Bill
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