Throw me a IPv6 bone (sort of was IPv6 ignorance)

Mike Jones mike at mikejones.in
Mon Sep 24 21:42:46 UTC 2012


On 24 September 2012 21:11, Adrian Bool <aid at logic.org.uk> wrote:
>
> On 24 Sep 2012, at 17:57, Tore Anderson <tore.anderson at redpill-linpro.com> wrote:
>
>> * Tore Anderson
>>
>>> I would pay very close attention to MAP/4RD.
>>
>> FYI, Mark Townsley had a great presentation about MAP at RIPE65 today,
>> it's 35 minutes you won't regret spending:
>>
>> https://ripe65.ripe.net/archives/video/5
>> https://ripe65.ripe.net/presentations/91-townsley-map-ripe65-ams-sept-24-2012.pdf
>
> Interesting video; thanks for posting the link.
>
> This does seem a strange proposal though.  My understanding from the video is that it is a technology to help not with the deployment of IPv6 but with the scarcity of IPv4 addresses.  In summary; it simply allows a number of users (e.g. 1024) to share a single public IPv4 address.
>
> My feeling is therefore, why are the IPv4 packets to/from the end user being either encapsulated or translated into IPv6 - why do they not simply remain as IPv4 packets?
>
> If the data is kept as IPv4, this seems to come down to just two changes,
>
> * The ISP's router to which the user connects being able to route packets on routes that go beyond the IP address and into the port number field of TCP/UDP.
> * A CE router being instructed to constrain itself to using a limited set of ports on the WAN side in its NAT44 implementation.
>
> Why all the IPv6 shenanigans complicating matters?

While you could do something similar without the encapsulation this
would require that every router on your network support routing on
port numbers, by using IPv6 packets it can be routed around your
network by existing routers. And it's not like anyone is going to be
deploying such a system without also deploying IPv6, so it's not
adding any additional requirements doing it that way.

- Mike



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