IPv6 Default Allocation - What size allocation for Loopback Address

William Herrin bill at herrin.us
Sun Oct 12 22:00:57 UTC 2014


On Sat, Oct 11, 2014 at 1:41 AM, Faisal Imtiaz <faisal at snappytelecom.net> wrote:
> A follow up question on this topic..
>
> For Router Loopback Address .... what is wisdom in allocating a /64 vs /128 ?
> (the BCOP document suggests this, but does not offer any explanation or merits of one over the other).

Hi Faisal,

One of the viewpoints held by some in the IETF is that an IPv6 address
is not 128 bits. Rather, it is 64 bits of network space and 64 bits of
host space. I'm told this viewpoint is responsible for the existence
of a 128 bit address instead of IPv6 using 64 bit addresses.

If you follow that reasoning, the subnet mask should always be /64, no
matter where the address is assigned.

There are, of course, excellent operational reasons not to religiously
follow that plan.

Regards,
Bill Herrin



-- 
William Herrin ................ herrin at dirtside.com  bill at herrin.us
Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>
May I solve your unusual networking challenges?



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