[130992] in North American Network Operators' Group
Re: Definitive Guide to IPv6 adoption
daemon@ATHENA.MIT.EDU (Mark Andrews)
Mon Oct 18 21:35:31 2010
To: Marshall Eubanks <tme@americafree.tv>
From: Mark Andrews <marka@isc.org>
In-reply-to: Your message of "Mon, 18 Oct 2010 20:45:30 EDT."
<35804BC3-9EFE-4CE4-B13A-F2E15C420EFA@americafree.tv>
Date: Tue, 19 Oct 2010 12:32:05 +1100
Cc: "Robert E. Seastrom" <rs@seastrom.com>, nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
In message <35804BC3-9EFE-4CE4-B13A-F2E15C420EFA@americafree.tv>, Marshall Euba
nks writes:
> It makes a bigger difference if everyone starts using 6RD - to give out =
> a /48 effectively=20
> requires a /16, and the number of /16s is by no means approximately =
> infinite.=20
>
> Regards
> Marshall
Only if you deploy 6rd in a naive manner. Encoding all of IPv4
into the IPv6 prefix you hand your customers in naive.
The best way is to just have a table that matches 6rd prefixes to
IPv4 blocks you have assigned. This table only changes when you
add or remove a IPv4 assignments from RIRs. You don't change
existing entries in the table. The entries are static for the life
of the IPv4 allocation.
<6rdPrefix1><6rdPefixLen1><IPv4Prefix1><IPv4PrefixLen1>
<6rdPrefix2><6rdPefixLen2><IPv4Prefix2><IPv4PrefixLen2>
<6rdPrefix3><6rdPefixLen3><IPv4Prefix3><IPv4PrefixLen3>
When you configure a IPv4 DHCP pool and associated router interface
you find the covering IPv4 prefix and plug in the values from the
table.
The next best way is to have a similar table but per covering IPv4/8
you have allocated. This is very wasteful but not as having a
IPv4PrefixLen of 0.
<6rdPrefix1><6rdPefixLen><192.0.0.0><8>
<6rdPrefix2><6rdPefixLen><202.0.0.0><8>
For the global naive case the table degenerates to a single row.
<6rdPrefix><6rdPefixLen><0.0.0.0><0>
As a exercise the first table was ~20 entries for Comcast Cable and
the second table about ~10 entries if I did the lookup correctly
so we are not talking about a lot of prefixes and they don't change
very often.
Mark
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka@isc.org
