IPv6 Default Allocation - What size allocation for Loopback Address

Mon Oct 13 07:52:46 UTC 2014

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 at arbor.net> het volgende geschreven:
> > 
> >> On Oct 11, 2014, at 2:09 PM, Tim Raphael <raphael.timothy at 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

ERNW GmbH - Carl-Bosch-Str. 4 - 69115 Heidelberg - www.ernw.de
Tel. +49 6221 480390 - Fax 6221 419008 - Cell +49 173 6745902 

Handelsregister Mannheim: HRB 337135
Geschaeftsfuehrer: Enno Rey

=======================================================
Blog: www.insinuator.net || Conference: www.troopers.de
Twitter: @Enno_Insinuator
=======================================================