" What about anycast-type addresses (e.g. DNS servers)? I route a few server IPv4 /32s around in my network; do you assign a /128, a /64 (with only one address in use), a /112, or something else?" Yes, on any sort of multi-access segment you really should use /64s. A little less stringent on an all router segment perhaps, but even then I shoot for /64s on anything that is not a PtP link ... /TJ -----Original Message----- From: Chris Adams [mailto:cmadams@hiwaay.net] Sent: Tuesday, October 13, 2009 9:15 PM To: nanog@nanog.org Subject: Re: ISP customer assignments Once upon a time, Leo Bicknell <bicknell@ufp.org> said:
2) Colon's separate 16 bit chunks in IPv6. /112's allow XXXX::1, XXXX::2 to be your IP's.
Yeah, this is what I forgot about. Makes sense now. Another (quite possibly dumb :-) ) few questions come to mind about IPv6 assignment: I would expect you just assign static addresses to servers. Are there pros/cons to using /64 or something else there? If I'm statically assigning IP (and DNS, etc. servers) info, why would I not just configure the gateway there as well (especially if you just make all local router interfaces ::1)? What about web-hosting type servers? Right now, I've got a group of servers in a common IPv4 subnet (maybe a /26), with a /24 or two routed to each server for hosted sites. What is the IPv6 equivalent? I can see a /64 for the common subnet, but what to route for aliased IPs for web hosts? It is kind of academic right now, since our hosting control panel software doesn't handle IPv6, but I certainly won't be putting 2^64 sites on a single server. Use a /112 here again as well? Use a /64 per server because I can? What about anycast-type addresses (e.g. DNS servers)? I route a few server IPv4 /32s around in my network; do you assign a /128, a /64 (with only one address in use), a /112, or something else?