Verizon DSL moving to CGN

Mon Apr 8 11:00:38 UTC 2013

On Mon, 8 Apr 2013, Tore Anderson wrote:

> * Mikael Abrahamsson
>
>> On Mon, 8 Apr 2013, Rajiv Asati (rajiva) wrote:
>>
>>> MAP is all about stateless (NAT64 of Encapsulation) and IPv6 enabled
>>> access. MAP makes much more sense in any SP network having its
>>> internet customers do IPv4 address sharing and embrace IPv6.
>>
>> It's still NAT.
>
> AIUI, the standards-track flavour of MAP, MAP-E, is *not* NAT - it is
> tunneling, pure encap/decap plus a clever way to calculate the outer
> IPv6 src/dst addresses from the inner IPv4 addresses and ports. The
> inner IPv4 packets are not modified by the centralised MAP tunneling
> routers, so there is no "Network Address Translation" being performed.

This is all splitting hairs. Yes, the outside port addresses do not change 
but however the src/dst addresses change (=translated), right? Does anyone 
see MAP-E being implemented on regular linecards or is it going to be 
implemented on processor based dedicated hardware? At least initially, I 
would just assume it's going to be some kind of CGN blade.

> The tunnel endpoint will 99.99% of cases be a CPE with a NAPT44 
> component though, so there is some NAT involved in the overall solution, 
> but it's pretty much the same as what we have in today's CPEs/HGWs. The 
> only significant difference is that a MAP CPE must be prepared to not 
> being able to use all the 65536 source ports.

Yes, MAP-E needs CPE support, thus hard to deploy short term. Long term, 
yes, really nice. Perfect for long tail IPv4 reachability over IPv6 access 
networks.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se