Re: IPv6 Default Allocation - What size allocation for Loopback Address

[Enno Rey <erey () ernw de>]

Hi,

On Sun, Oct 12, 2014 at 02:53:36PM +0200, Sander Steffann wrote:
> Hi,
>
> > Op 11 okt. 2014, om 23:00 heeft Roland Dobbins <rdobbins () arbor net> het volgende geschreven:
> >
> > > On Oct 11, 2014, at 2:09 PM, Tim Raphael <raphael.timothy () gmail com> wrote:
> > >
> > > > From my research, various authorities have recommended that a single /64 be allocated to router loopbacks with 
> > > > /128s assigned on interfaces.
> > >
> > > Yes, this is what I advocate for loopbacks.
>
> I often use the first /64 for loopbacks.

I'm not a big fan of using all-zero third or fourth quarters of $PREFIX at all (at least not if one follows RFC 5952 & 
uses static, short IIDs, which will be case for loopbacks).
On a crowded visio diagram it might not be easy to spot that 2001:db8::1, 2001:db8:0:1::1, 2001:db8:1::1 and 
2001:db8:1:1::1 are all different addresses, potentially on the same hierarchy level.
Hence we prefer to use FFFF or just FF "at some point within the prefix" for loopbacks, e.g. 2001:db8:FF::1 etc.

best

Enno





 Loopbacks are often used for management, iBGP etc and having short and easy to read addresses can be helpful. 
Something like 2001:db8::1 is easier to remember and type correctly than e.g. 2001:db8:18ba:ff42::1 :)
> Cheers,
> Sander

-- 
Enno Rey

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