Cogent IPv6

Aftab Siddiqui aftab.siddiqui at
Thu Jun 9 06:58:56 UTC 2011

> I had to ask this here a while back, so I can now share. :-)
> IPv6 addresses are written as 8 16-bit chunk separated by colons
> (optionally with the longest consecutive set of :0 sections replaced
> with ::).  A /112 means the prefix is 7 of the 8 chunks, which means you
> can use ::1 and ::2 for every connection.
> Of course, just because you allocate a /112 (or shorter) in your
> database doesn't mean you have to use it.  You could also allocate a
> /112 for a point-to-point link and use a /127 (e.g. addresses ::a and
> ::b).
Still that doesn't give any reason to provide /112 for point to point
connectivitiy. Seriously, I'm peering with a transit provider with /126 and
when I asked for a reason they said, ease of management. How come Subnetting
/32 to /126 is ease of management??.... thats quite difficult to understand.
This debate is there fore quite a long time but everytime it pops up I
feel so uncomfortable with this granular subnetting.


Aftab A. Siddiqui

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