Using /126 for IPv6 router links

From: "TJ" <>
Date: Mon, 25 Jan 2010 15:15:55 -0500

> From: Tim Durack []
> Sent: Monday, January 25, 2010 14:03
> To: TJ
> Cc:
> Subject: Re: Using /126 for IPv6 router links


> 2^128 is a "very big number." However, from a network engineering
> perspective, IPv6 is really only 64bits of network address space. 2^64
> is still a "very big number."
> An end-user assignment /48 is really only 2^16 networks. That's not
> very big once you start planning a human-friendly repeatable number
> plan.
> An ISP allocation is /32, which is only 2^16 /48s. Again, not that big.
> Once you start planning a practical address plan, IPv6 isn't as big as
> everybody keeps saying...

I didn't realize "human friendly" was even a nominal design consideration,
especially as different humans have different tolerances for defining
"friendly" :slight_smile:

It was absolutely an issue. The excellent A6 proposal was killed because
it was not human friendly. Very computer friendly, but people were not
too happy about dealing with it. It was, in most ways, vastly superior
to AAAA, but a real pain to try to deal with "by hand".