There are certainly other solutions to the issue of IPv4 runout within the ISP that do not require CPE change - certainly a plug for some of the work I have done (and at least one vendor is implementing) is the L2-Aware NAT: draft-miles-behave-l2nat-00. In AU/NZ we see a lot of subsidised CPE, and often this CPE is significantly trimmed in terms of flash, memory and CPU. I have heard from at least one modem vendor that their lowest cost CPE simply cannot do DS-Lite faster than 5Mbps. Certainly the counter-argument goes along the lines of "you need new CPE for IPv6 anyway", so take with a grain of salt, but the reality is that we are in an IPv4- dominated world, so continuity of service is critical. One thing that seems to be missing is a discussion on how an ISP will roll such services out to market (NAT44, DS-Lite, etc). Only addressing new customers or new markets seems non-sensical, so it would appear ISP may be forced to introduce a lower-cost plan to try and entice customers to use a NAT solution (which DS-Lite certainly is). The bottom line is that all solutions involve NAPT and will have application compatibility problems. If an ISP must launch a somewhat crippled product to market at a lower price-point (but higher cost) then IPv4-continuity is boiled down into a cost-reduction exercise. I speculate that an ISP would logically seek the lowest-cost solution, which would be to avoid CPE change. My -individual- 2c d On 15/10/2009, at 7:40 AM, Brian E Carpenter wrote:
Nathan,
About ds-lite. I don't think it's insanity. It's what you do if either (a) you have run out of IPv4 addresses even *within* the ISP network. That is Comcast's story. (Yes, they are a little bigger than all NZ ISPs added together.) or (b) your funding agency requires you to run an IPv6-only core. That is CERNET's story. (Yes, their funding agency runs the largest country in the world, and seems to think that having fewer addresses than people is stupid.)
As for possible ISP scenarios, I think there are going to be more. Watch for an Internet-Draft coming your way very soon.
Brian
On 2009-10-14 19:01, Nathan Ward wrote:
I keep getting asked about whether to use technology X or Y when deploying an IPv6 network, especially 'transition'/'tunneling'/'coexistence' technologies.
Copypasta from a post I mate to NANOG just now. Sorry if you've read this before, but I think it'll be a useful resource for people:
Instead of explaining the options over and over and hoping people can make sense of the complexities of it, become experts, and make good informed decisions, I've made a flow chart. Feel free to ask about details and I can get in to the ranting part, this is really a place to start.
Right now it assumes people only provide DSL or other dynamic sort of services. It also assumes DS-Lite people are insane, so probably need better language there. Also the first question is not necessarily about who you are, but who is driving the IPv6 'build' - which is why native, 6rd and ds-lite are not appropriate for the customer-driven side. I hope that makes sense. No talk about ISATAP and stuff for inside the customer network either. And before you ask no ISATAP is not appropriate for ISPs, doesn't work through NAT.
Anyway: - 6RD is used by free.fr. Not widely implemented by anyone yet. - DS-Lite is something some guys at Comcast and others are talking about. Not widely implemented by anyone yet. - The rest you can figure out from wikipedia and stuff.
Please email me with any corrections, complaints, or threats if you're a DS-Lite fan. I'll always keep old versions in this directory, and the latest version will always have this filename, so please link to it instead of copying it, etc. etc.:
http://www.braintrust.co.nz/resources/ipv6_flow_chart/ipv6_flow_chart-curren...
-- Nathan Ward
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