ISP customer assignments

[nanog at daork.net (Nathan Ward)]

On 14/10/2009, at 3:49 PM, Chris Adams wrote:

> Once upon a time, Nathan Ward <nanog at 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).

Yeah I figured as much.

> 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).

I guess. The advantage of doing it with a single /64 for all of them  
is that you can move individual sites to other servers without much  
drama. That might not be useful for everyone of course.

--
Nathan Ward