Re: Comment on draft-carpenter-6man-why64

[Glen Turner <[e-mail]>]

On 21/03/2014, at 11:54 AM, Philip Matthews wrote:

> 
> On 2014-03-19, at 20:18 , Brian Jones wrote:
>> >
>> > Does anyone dispute that manual configuration of longer than /64 prefixes are and should be permitted, but are generally not recommended?
>> >
>> 
>> I agree; Prefixes > /64 should be allowed. It doesn't have to be recommended but also shouldn't be restricted.
>> 
> For what it is worth, I also agree.
> My personal opinion is: Implementations should do VLSM, but BCP is /64, and the draft should argue why /64 is BCP.  

This is also my view, as it allows for an evolving best common practice and prevents hardware vendors assuming /64 in the forwarding plane.

For example /124 is operationally attractive for statically-addressed router-router links. The textual representation is sane. But more importantly using something much smaller than a /64 allows all of an ISPs point-to-point infrastructure links to be covered in one statement in an access control list. *NIC aren't going to allocate further addressing if you have a massively under-utilised address space because a lot of space is reserved by the bits you are using to identify infrastructure so using /64 for router-router links leads to a mess of ACL entries because each *NIC allocation has an infrastructure range.

-glen