IPv6: numbering of point-to-point-links

Tim Durack tdurack at gmail.com
Tue Jan 25 09:25:56 CST 2011

On Tue, Jan 25, 2011 at 9:44 AM, Lasse Jarlskov <laja at telenor.dk> wrote:
> Thank you all for your comments - it appears that there is no consensus
> on how this should be done.

The best piece of advice I received when asking similar questions in
the past is to allocate a /64 for every network regardless of it's
potential size. Loopbacks, point-to-point, hosting VLANs etc. Then
assign whatever size you are currently comfortable with.

We've used /128s for loopbacks, safe in the knowledge that we can
expand them all to /64s without renumbering (in case someone comes up
with a good idea why /64s on loopbacks are necessary.)

We've gone unnumbered on point-to-points, as a way of deferring that
particular decision. Admittedly this reduces useful diagnostics
available from traceroutes, although I quite like seeing loopbacks in
traceroutes anyway. Unnumbered does reduce control-plane address space
surface, which might be seen as a useful benefit (I'm sure someone
will tell me why that's a bad idea.)

My point is, if you do your number plan right, you should have some
flexibility to make changes in the future without pain.


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