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.
charles On Sat, Apr 4, 2015 at 8:35 PM, Mike Hammett <na...@ics-il.net> wrote: > Okay, so I decided to look at what current IXes are doing. > > It looks like AMS-IX, Equinix and Coresite as well as some of the smaller > IXes are all using /64s for their IX fabrics. Seems to be a slam dunk then as > how to handle the IPv6. We've got a /48, so a /64 per IX. For all of those > advocating otherwise, do you have much experience with IXes? Multiple people > talked about routing. There is no routing within an IX. I may grow, but an IX > in a tier-2 American city will never scale larger than AMS-IX. If it's good > enough for them, it's good enough for me. > > Back to v4, I went through a few pages of PeeringDB and most everyone used a > /24 or larger. INEX appears to use a /25 for each of their segments. IX > Australia uses mainly /24s, but two locations split a /24 into /25s. A couple > of the smaller single location US IXes used /25s and /26s. It seems there's > precedent for people using smaller than /24s, but it's not overly common. > Cash and address space preservation. What does the community think about IXes > on smaller than /24s? > > > > > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > > > ----- Original Message ----- > > From: "Brendan Halley" <bren...@halley.net.au> > To: "Mike Hammett" <na...@ics-il.net> > Cc: nanog@nanog.org > Sent: Saturday, April 4, 2015 6:10:34 PM > Subject: Re: Small IX IP Blocks > > > IPv4 and IPv6 subnets are different. While a single IPv4 is taken to be a > single device, an IPv6 /64 is designed to be treated as an end user subnet. > https://tools.ietf.org/html/rfc3177 section 3. > On 05/04/2015 9:05 am, "Mike Hammett" < na...@ics-il.net > wrote: > > > That makes sense. I do recall now reading about having that 8 bit separation > between tiers of networks. However, in an IX everyone is supposed to be able > to talk to everyone else. Traditionally (AFAIK), it's all been on the same > subnet. At least the ones I've been involved with have been single subnets, > but that's v4 too. > > > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > > > ----- Original Message ----- > > From: "Valdis Kletnieks" < valdis.kletni...@vt.edu > > To: "Mike Hammett" < na...@ics-il.net > > Cc: "NANOG" < nanog@nanog.org > > Sent: Saturday, April 4, 2015 5:49:37 PM > Subject: Re: Small IX IP Blocks > > On Sat, 04 Apr 2015 16:06:02 -0500, Mike Hammett said: > >> I am starting up a small IX. The thought process was a /24 for every IX >> location (there will be multiple of them geographically disparate), even >> though >> we nqever expected anywhere near that many on a given fabric. Then okay, how >> do > < we d o v6? We got a /48, so the thought was a /64 for each. > > You probably want a /56 for each so you can hand a /64 to each customner. > > That way, customer isolation becomes easy because it's a routing problem. > If customers share a subnet, it gets a little harder.... > > > >
