ISP customer assignments

Kevin Loch kloch at kl.net
Wed Oct 14 00:27:55 UTC 2009


Chris Adams wrote:
> I guess I'm missing something; what in section 3 is this referring to?
> I can understand /64 or /126 (or maybe /124 if you were going to
> delegate reverse DNS?), but why /112 and "16 bits for node identifiers"
> on a point-to-point link?

The only thing special about /112 is that it is on a ":" boundary
so it makes for some nice numbering plans:

Let's say you set aside 2001:xxxx:0:1::/64 for /112's

link 1:
2001:xxxx:0:1::1:1
2001:xxxx:0:1::1:2

link 2:
2001:xxxx:0:1::2:1
2001:xxxx:0:1::2:2

This :1, :2 arrangement seems to be common but for internal links you
could make the last hextet be a unique id for the specific router.
That could use more than a few bits in a large network.

- Kevin





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