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Re: Verizon DSL moving to CGN
From: Mikael Abrahamsson <swmike () swm pp se>
Date: Mon, 8 Apr 2013 13:00:38 +0200 (CEST)

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 () swm pp se

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