Dual stack IPv6 for IPv4 depletion

Mon Jul 6 13:26:27 UTC 2015

Some thoughts. . .

³Native dual-stack² is ³native IPv4 and native IPv6.²

³Dual-stack² might be native, or might by ³native IPv6 plus IPv4 address
sharing.²

Your IPv4 address sharing options are CGN, DS-Lite, and MAP. There are
operational deployments of all three, in the order given. You need them
close enough to your customers that traffic will return over the same
path. You can¹t share state among a cluster of boxes, but that¹s not the
end of the world; a device failure sometimes causes loss of state. MAP is
the hot new thing all the cool kids are doing.

Look to your router and load balancer vendors for devices that do these.
CGN is the only one that doesn¹t require updates to the home gateway. The
more IPv6 your customers use, the smaller your CGN/AFTR/MAP can be.

Think about how you¹ll position it to customers. It¹s difficult to change
a customer¹s service mid-contract. At some point, a customer is no longer
profitable: if NAT costs and service calls add up, you may be better off
buying addresses or losing the customer. You may need to buy some IPv4
addresses to give you time; contact a broker.

You may be surprised how hard it is to root IPv4 out of the system. Don¹t
buy anything you can¹t manage over IPv6, including servers and
applications. Sorry, vendor, I can¹t buy your cluster, I don¹t have the
IPv4 address space to provision it.

Lee

On 7/4/15, 8:09 AM, "NANOG on behalf of Josh Moore"
<nanog-bounces at nanog.org on behalf of jmoore at atcnetworks.net> wrote:

>Traditional dual stack deployments implement both IPv4 and IPv6 to the
>CPE.
>Consider the following:
>
>An ISP is at 90% IPv4 utilization and would like to deploy dual stack
>with the purpose of allowing their subscriber base to continue to grow
>regardless of the depletion of the IPv4 space. Current dual stack best
>practices seem to recommend deploying BOTH IPv4 and IPv6 to every CPE. If
>this is the case, and BOTH are still required, then how does IPv6 help
>with the v4 address depletion crisis? Many sites and services would still
>need legacy IPv4 compatibility. Sure, CGN technology may be a solution
>but what about applications that need direct IPv4 connectivity without
>NAT? It seems that there should be a mechanism to enable on-demand and
>efficient IPv4 address consumption ONLY when needed. My question is this:
>What, if any, solutions like this exist? If no solution exists then what
>is the next best thing? What would the overall IPv6 migration strategy
>and goal be?
>
>Sorry for the length of this email but these are legitimate concerns and
>while I understand the need for IPv6 and the importance of getting there;
>I don't understand exactly HOW that can be done considering the immediate
>issue: IPv4 depletion.
>
>
>Thanks
>
>Joshua Moore
>Network Engineer
>ATC Broadband
>912.632.3161