Once upon a time, Nathan Ward <nanog@daork.net> said:
On 14/10/2009, at 2:14 PM, Chris Adams wrote:
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?
Why route them to the servers? I would just put up a /64 for the web servers and bind addresses to your ethernet interface out of that /64 as they are used by each site. I guess you might want to route them to the servers to save ND entries or something on your router?
In the past, we saw issues with thousands of ARP entries (it has been a while and I don't remember what issues now though). Moving a block from one server to another didn't require clearing an ARP cache (and triggering a couple of thousand new ARP requests). Also, it is an extra layer of misconfiguration-protection: if the IPs are routed, accidentally assigning the wrong IP on the wrong server didn't actually break any existing sites (and yes, that is a lesson from experience). Of course, with IPv4, you never assigned a large enough block to begin with that would anticipate all growth, so routing additional blocks was a lot easier than changing blocks, cleaner than secondary IPs multiplying like crazy, etc., etc. None of that would be an issue with a single /64. -- Chris Adams <cmadams@hiwaay.net> Systems and Network Administrator - HiWAAY Internet Services I don't speak for anybody but myself - that's enough trouble.