[Softwires] DS-Lite vs. 4rd

Edward Lopez <elopez@fortinet.com> Wed, 21 October 2015 12:29 UTC

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From: Edward Lopez <elopez@fortinet.com>
To: "softwires@ietf.org" <softwires@ietf.org>
Thread-Topic: DS-Lite vs. 4rd
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Date: Wed, 21 Oct 2015 12:29:26 +0000
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Subject: [Softwires] DS-Lite vs. 4rd
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I apologize if this has been thrashed out in the past.  In looking as implementing DS-Lite support, it appears that the need to include an additional tuple of information on the IPv6 B4 address of the CPE is cumbersome to NAT performance and tunnel capacitance, as many HW accelerated NAT engines exist without this extra tuple.  It would appear that by splitting the AFTR into two functions, 4in6 encapsulation & NAT(CGN), we can overcome scaling and performance issues of DS-Lite.

However, the issue of overlapping endpoint subnets supported internally by the CPE leads to the issue potentially supporting NAT44 on the CPE, to support stateless encapsulation of returning IPv4 packets into IPv6 by the AFTR.  Section 4.2 of RFC-6333 states that CPE devices ‘should not’ perform NAT44, but that’s not the same as a ‘must not’

But as you craft this solution out, you begin to realize that you are re-creating the majority of 4rd, RFC-7600.  However, 4rd is currently an experimental standard.

My questions:

-	Has anyone implemented or considered implementing DS-Lite with CPEs performing NAT44?
-	Are their plans for this WG to move 4rd into standards track?
-	Are their any known implementations of 4rd out there for CPE devices (like OpenWRT)?

Ed Lopez
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