How to wish you hadn't forced ipv6 adoption (was "How to force rapid ipv6 adoption")
owen at delong.com
Sat Oct 3 19:03:58 UTC 2015
> On Oct 2, 2015, at 06:44 , Stephen Satchell <list at satchell.net> wrote:
> On 10/02/2015 12:44 AM, Valdis.Kletnieks at vt.edu wrote:
>> On Fri, 02 Oct 2015 02:09:00 -0400, Rob McEwen said:
>>> Likewise, sub-allocations can come into play, where a hoster is
>>> delegated a /48, but then subdivides it for various customers.
>> So they apply for a /32 and give each customer a /48.
>> A hoster getting *just* a /48 is about as silly as a hoster
>> getting a /32 of IPv4 and NAT'ing their customers.
> I agree, for a web hosting operation, getting an allocation smaller than a /32 doesn't make sense.
> But...now I ask this question: WHY a /48 per customer? I used to be a web host guy, and the rule was one IPv4 address per co-location customer or dedicated-server customer -- maybe two -- and shared-IP HTTP for those customers hosted on "house" servers with multiple sites on them. We had a couple of shared-hosting server with 64 IPv4 addresses each to support SSL sites with customer-provided SSL certificates..
> OLD STYLE
> If a customer wanted more than one IPv4 address, he had to justify it so we could copy the justification to our ARIN paperwork. A /24 was right out, because the *only* people requesting that much IPv4 space were spammers.
> The largest legit co-location IPv4 customer allocation, because he had enough servers in his cage and sufficient justification to warrant it, was a /26 . Which I SWIPped. Which I treated as a completely separate subnet. Which was on its own VLAN. Which used separate 10base-T Ethernet interfaces on my edge routers to provide hard flow control and traffic monitoring.
> THAT WAS THEN, THIS IS NOW
> I can see, in shared hosting, where each customer gets one IPv6 address to support HTTPS "properly". Each physical server typically hosts 300-400 web sites comfortably, so assigning a /112 to each of those servers appears to make sense. This is particularly true now that there is a push for "https everywhere".
> Web hosting isn't going to be a downstream link for IoT, so the need for "massive" amounts of IPv6 addressing space is simply not there.
So there are a number of reasons.
First, unless you want to be chasing ND Cache Overflow problems, you put each customer on a small link (/127) to your router and then route at least a /64 to their router if they just have one subnet. If they have more than one, then you certainly want to route them a larger prefix (/48).
With virtualization and network virtualization, containers, and the like these days, treating each customer as a separate end-site is just good practice. You’re not going to have any problem explaining that to the RIRs.
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