How to choose IPv6 addresses for customer links?

S.P.Zeidler spz at
Sun Feb 1 13:33:41 CET 2009

Thus wrote Jeroen Massar (jeroen at

> Martin List-Petersen wrote:
> > Martin Horneffer wrote:
> > [SNIP]
> >> Would that be a sensible addressing scheme? Or would a customer insist
> >> to get a completely independet /64 for the link addresses?
> > 
> > SixXS uses the approach commonly of assigning the link-addresses out of
> > a seperate /48 in the PoP. One /40 per PoP.

[some good technical points]

> Btw, you should have already done all of this when REQUESTING your
> prefix from RIPE. Numberplans are important to them, they should also be
> important to you.

I wouldn't exactly call it wrong to check ones plans against other
peoples experience every once in a while. Best practise does change over

That said: an address plan I was involved with in the past asked for
leased lines to be numbered with a /64 from the specific PoPs /48,
expecting a router on the other side, and throwing a full /48 to the
customer. That makes routing easier if the customer has site resilient
links, too.

For datacenter connections it also fed /64 from the datacenter /48
and only gave /48 if the customer had a router installed. It's expected
that the customer would rarely exhaust a /64 in a flat network ;-P
All in all, KISS is a very useful principle and one ought to step away
from it only if it's really neccessary. :)

spz at (S.P.Zeidler)

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