[167056] in North American Network Operators' Group
Re: AT&T UVERSE Native IPv6, a HOWTO
daemon@ATHENA.MIT.EDU (Jean-Francois.TremblayING@videotro)
Fri Nov 29 08:47:54 2013
In-Reply-To: <alpine.DEB.2.02.1311290832350.1157@uplift.swm.pp.se>
To: "nanog@nanog.org" <nanog@nanog.org>
From: Jean-Francois.TremblayING@videotron.com
Date: Fri, 29 Nov 2013 08:47:38 -0500
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> De : Mikael Abrahamsson <swmike@swm.pp.se>
> A : Mark Andrews <marka@isc.org>,
> >>> You can hand out /48 as easily with 6rd as you can natively.
>
> "As easily". It's easier to either hand out /64 by means of 1:1 mapping
> IPv4 and IPv6, or (if ability exists) hand out /48 or /56 using PD, than
> to get into the whole backend mess of having multiple 6RD domains with
> multiple configs per IPv4 subnet etc.
>
> I agree with you theoretically, but in practice I disagree.
Some hard data points here, coming from one of the rare operator
who actually deployed 6RD sub-domains to all its customers (to my
knowledge).
In practice, most 6RD implementations that support option 212 do
support IPv4MaskLen properly these days. It wasn't the case 3 years ago,
but we worked a lot with vendors to make it right. Seems ok now,
we mostly have a 6RD population of D-Link and Cisco/Linksys.
On the backend side, it's really not that bad. A one-page TCL
handles around 15-16 sub-domains for us without noticeable impact
on the DHCP servers CPU. Configuring the relays with all the
tunnels can be a bit of fun playing with hex maths, but it's
not too bad either.
So I agree with Mark, it's not that complex. I can't agree with
him on the prefix size though. We hand out /60s because we feel
it's enough from a transition point of view (these are short-lived
anyway) and offering a bigger size would really use too much space.
Offering /48s out of a single /16 block, to take a simple example,
would use a whole /32. This space wouldn't be used much anyway,
given that most 6RD routers use only one /64, sometimes two.
I argue that a /60 is actually the best compromise here, from
a space and usage point of view.
/JF
Videotron, AS5769
