[address-policy-wg] IPv6 allocations for 6RD

Greetings,

Compared to 6RD, the TSP protocol (RFC 5572) can also rapidly deploy IPv6, needing one /32 allocation while customer site prefixes can be /64, /56 or /48. Reason is TSP doesn't embed the customer's IPv4 address in its IPv6 address as 6RD does.

Being a hot topic nowadays, its worth mentioning customer site access gear (CPE) requirements are more relaxed with TSP as it doesn't need the Service Provider IPv4-only access modem to be changed or upgraded. A TSP client can run in a small hardware device (thru an Ethernet interface connection) or a software client in the home network behind the SP modem while enabling all v6 capable nodes with the assigned prefix by automatically establishing a tunnel to the SP TSP tunnel server.

Since TSP allows for static prefix assignment and larger prefixes than /64 without wasting v6 space, this would mimic a native deployment more closely. The stateful tunneling could be seen as any other encapsulation in the access, and a few service providers have it running already.

In the long term, both 6RD and TSP will give way to reverse tunneling i.e. v4-in-v6, as this is the only way (after IPv4 depletion) for both protocols to co-exist on a host while having a mix of v4-only and dual-stack accessible services/website. Reverse tunneling's current protocols, DS-Lite and DSTM, are very similar to TSP's concept so the same clients & servers supporting TSP can be adapted to support DS-Lite.

Unfortunately, until IPv4 disappears from web content, hosts and servers these coexistence mechanisms will be needed.

Regards,
-Ahmed




From: Kurt Smolderen 
Sent: Monday, February 28, 2011 11:13 AM
To: address-policy-wg at ripe.net 
Subject: RE: [address-policy-wg] IPv6 allocations for 6RD


I strongly support the idea of assigning a smaller prefix to ISPs which are in a state of deploying IPv6 but need to use transitional mechanism for (some of) their customers. Mark has described one of the problems very clear in his email: if an ISP has only a /32 prefix and needs to use all 32 IPv4 bits in the 6rd configuration, only a /64 can be delivered to the home instead of the desired /56 or /48. Needing all 32 bits is for instance the case when an ISP offers internet connectivity to some of its customers via a partnership with another ISP.

However, I want to point to an additional problem which appears when an ISP wants to deploy native IPv6 but needs to roll out 6rd (or any other transitional technique) as well. For native IPv6, the ISP will create an IPv6 addressing plan. This will normally include separate prefixes for the ISP's own servers, the ISP's backbone, the ISP's customers etc. For the 6rd domain, the full /32 range is however needed. So at this stage, the ISP has two options:
1) Implement 6rd only
2) Implement native IPv6 only and exclude some customers from being able to use IPv6 (those which would normally be connected through 6rd)

I strongly believe we all agree 6rd is only a temporary solution. So I can't imagine we would prefer skipping native IPv6 deployments in favor of IPv6 transitional mechanisms.
I also believe we all agree we should enable IPv6 for as much customers as we can, which makes me conclude the second 'option' is not really an option at all...

My primary concern is that any ISP - regardless of how small or big it is - can independently of other organizations/ ISPs move forward with IPv6 deployment. RIPE can support this by adapting a policy which - albeit for a limited time span - allows the assignment of a contiguous IPv6 prefix which size does not only depend on the amount of customers the ISP has, but also incorporates the needed technologies to 'IPv6-enable' as much customers as possible.
 
Regards,
-Kurt
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