[afnog] XLAT646 deployment

[Mark Tinka]

On 7/4/21 16:47, Joel Jaeggli wrote:

> One of the key issues with 464xlat as with all transition mechanisms 
> is the one of coordination. if you control the cpe then you use a cpe 
> that embeds the transition technology of your choice. if you don't, 
> either because the cpe belongs to to the consumer or because you buy 
> retail devices based on a minimum set of interoperability requirements 
> or cost, then your presentation will necessarily be driven by the 
> minimum you are willing to support. Large MNOs and MSOs have a 
> structural advantage when it comes to negotiating with CPE vendors. As 
> you observe moving the CPE up the wire so that handoff is in the form 
> of a device not performing the traditional cpe function, or an 
> ethernet port, ont, or wireless bridge; provides you the opportunity 
> to virtualize the functions of the cpe so they can be placed in 
> something more accomidating like a linux vm.
>
> In the case of 464xlat if you cannot embed the clat in the cpe, you 
> can place it upstream in a device you control. doing so effectively 
> means dual stacking down to the CPE.  Your plat  still ends up having  
> a stateful nat64 function which is very similar in cost to the 
> stateful nat44 function. To me the question is not one of whether to 
> dual stack or not (464xlat folks are clearly committed to providing 
> dual stack services) but rather one of scope, where the middle box 
> functions are expected to reside and who controls them.

Agreed.

If you are offering services via a vCPE in the core, then your only 
limitation is whether the customer's devices support IPv6 or not. 
Chances are they do, in which case, simply offering dual-stack IP 
connectivity at the vCPE for terminating customers reduces the 
requirement for 464XLAT altogether.

But for as long as some resources on the web continue to be 
single-stacked to IPv4, 464XLAT would not be entirely useless.

Yes, the PLAT would need to hold state in the same way NAT44 CGN's 
would, but the difference is that as more of the world activates IPv6 
support for their network and services, you put less emphasis on the 
PLAT (which cuts costs as well). With NAT44, your costs just keep rising 
the longer you hold out against committing to IPv6.

Mark.