Using /126 for IPv6 router links

James Hess mysidia at
Sun Jan 24 02:24:47 UTC 2010

On Sat, Jan 23, 2010 at 5:51 PM, Dobbins, Roland <rdobbins at> wrote:
> It isn't 'FUD'.
> redistribute connected.
In that case, the fault would lie just as much with the unconditional
redistribution policy, as the addressing scheme,  which is error-prone
in and of itself.

No matter how you address your links or what type of equipment on your
network,  it's probably possible to find some configuration error that
will produce  poor router behavior.

> I'm not too sure of the math behind this - and it was just one example.   The
>gazillions of one-time-use nanomachines used to scrape away plaque in just a
>single patient's bloodstream, et. al., argue against needless consumption of IP
>addresses, IMHO.  Not to mention all the smart material molecules continuously

The trouble is both of the examples, is they both imply something far
greater than mere needless consumption of IP addresses in and of
themselves.     Assigning  global  IP addresses to individual
nanonites is a massive waste in and of itself.

It is easy to logically reject needlessly assigning each nanonite as
an IP address,  because they are obviously too massive in number to
easily achieve a sane addressing scheme.     My point is that in the
face of such massive waste,  the smaller amounts of "needless
consumption"  become irrelevent.

If you are justifying consuming   2*10**25   IP addresses on
one-time-use  nanonites,  you can certainly  spend  5% of your IPv6
address space on  point-to-point links   without the P-t-P  links
being the issue.
5% would be   >100,000   P-t-P  links in that case.

Either way,   one  /43  would  easily  provide more than enough IPs
for both nanonites and  100,000 /64 p-t-p links.   And with a standard
/40  subnet, you'd  have  4 additional bits  left over to work with,
to sanely  subnet your nanonites.

The issue in scenarios like that one is the things there are a lot of
that _consume_   many addresses.

Point-to-point addresses are rare,  much rarer than hosts, and much
less massive in number than nanonites addressed onto a LAN would be,
so giving a P-t-P link an an entire  /64   should not be a
consumption issue  in any  conceivable  (likely) scenario,  where a
proper amount of  IPv6 space has been obtained in the first place.


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