[153327] in North American Network Operators' Group
Re: IPv6 day and tunnels
daemon@ATHENA.MIT.EDU (Owen DeLong)
Tue Jun 5 02:10:58 2012
From: Owen DeLong <owen@delong.com>
In-Reply-To: <4FCD5CDC.3060209@unfix.org>
Date: Mon, 4 Jun 2012 23:06:31 -0700
To: Jeroen Massar <jeroen@unfix.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jun 4, 2012, at 6:11 PM, Jeroen Massar wrote:
> On 2012-06-04 17:57, Owen DeLong wrote:
> [..]
>> If you're going to redesign the header, I'd be much more interested
>> in having 32 bits for the destination ASN so that IDR can ignore IP
>> prefixes altogether.
>=20
> One can already do that: route your IPv6 over IPv4.... IPv4 has 32bit
> destination addresses remember? :)
>=20
> It is also why it is fun if somebody uses a 32-bit ASN to route IPv4, =
as
> one is not making the problem smaller that way. ASNs are more used as
> identifiers to avoid routing loops than as actual routing parameters.
>=20
> Greets,
> Jeroen
While this is true today (to some extent), it doesn't have to always be =
true.
If we provided a reliable scaleable mechanism to distribute and cache =
prefix->ASN mappings and could reliably populate a DEST-AS field in the =
packet header, stub networks would no longer need separate ASNs to =
multihome and IDR routing could be based solely on best path to the =
applicable DEST-AS and we wouldn't even need to carry prefixes beyond =
the local AS border.
While I don't think DNS is up to the task of reliable distribution and =
caching (though something somewhat similar to DNS could do the job =
rather well), DNS-style resource records could be used. For example, =
instead of using my own AS1734 as I do today, my multi-homed household =
could be placed in the database with pointers to my two upstream ASNs as =
follows:
2620:0:930::/48 AS 10 6939
AS 10 =
8121
192.124.40.0/23 AS 10 6939
AS 10 =
8121
192.159.10.0/24 AS 10 6939
AS 10 =
8121
Or, if I wanted to do some traffic engineering, I could tweak the =
preferences to be non-equal values.
The router doing the DEST-AS insertion into the packet would grab the =
most preferred AS to which it has a valid feasible successor.
I believe that the number of transit autonomous systems on the planet is =
much smaller than the minimum number of prefixes to represent all =
multi-homed organizations with independent routing policies. As such, I =
believe this could produce much more scalable routing with relatively =
little additional overhead.
Owen
