Nat

Sat Dec 19 16:56:01 UTC 2015

Hi,

> On Dec 19, 2015, at 11:41 AM, Mike Hammett <nanog at ics-il.net> wrote:
> 
> "A single /64 has never been enough and it is time to grind that 
> myth into the ground. ISP's that say a single /64 is enough are 
> clueless." 
> 
> 
> 
> LLLLOOOOOOLLLLL 
> 
> 
> A 100 gallon fuel tank is fine for most forms of transportation most people think of. For some reason we built IPv6 like a fighter jet requiring everyone have 10,000 gallon fuel tanks... for what purpose remains to be seen, if ever. 
> 
> 

You’re being deliberately flippant.

There are technical reasons why a single /64 is not enough for an end user.  A lot of it has to do with the way auto configuration works.  The lower 64 bits of the IP address are essentially host entropy.  EUI-64 (for example) is a 64 bit number derived from the mac address of the NIC.

The requirement for the host portion of the address to be 64 bits long isn’t likely to change.   Which means a /64 is the smallest possible prefix that can be assigned to an end user and it limits said end user to a single subnet.

Handing out a /56 or a /48 allows the customer premise equipment to have multiple networks behind it.  It’s a good practice and there’s certainly enough address space available to support it.