[135593] in North American Network Operators' Group
Re: Using IPv6 with prefixes shorter than a /64 on a LAN
daemon@ATHENA.MIT.EDU (Fernando Gont)
Wed Jan 26 23:10:38 2011
Date: Thu, 27 Jan 2011 01:09:43 -0300
From: Fernando Gont <fernando@gont.com.ar>
To: Owen DeLong <owen@delong.com>
In-Reply-To: <E58532F0-F1E4-4E17-BC4D-0A96D5A7BC18@delong.com>
Cc: nanog@nanog.org, carlos@lacnic.net
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 26/01/2011 06:14 a.m., Owen DeLong wrote:
>>> That said. Any size prefix will likely work and is even permitted by
>>> the RFC. You do run the risk of encountering applications that assume
>>> a 64-bit prefix length, though. And you're often crippling the
>>> advantages of IPv6.
>>
>> Just curious: What are the advantages you're referring to?
>>
> 1. Sparse addressing
This comes at a cost, though.
> 2. SLAAC
> 3. RFC 4193 Privacy Addressing
Privacy Extensions "solve" (*) a privacy issue *introduced* by SLAAC
embedding the MAC addresses in the IID. -- So, if anything, I deem this
as a patch, rather than a feature.
(*) there is some bibliography about the effectiveness of privacy
addresses. Some have even argued that they are harmful.
> 4. Never have to worry about "growing" a subnet to hold new machines.
As in #1, this comes at a price.
> 5. Universal subnet size, no surprises, no operator confusion, no bitmath.
With quite a bit of experience with subnetting (from IPv4), I doubt this
can be flagged as a benefit.
Thanks,
--
Fernando Gont
e-mail: fernando@gont.com.ar || fgont@acm.org
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1
