i can use dual stack in our own system , which include the Radius server , AAA , DNS servers , Routers (gateway & Bras)
When you say you can do that, do you mean you already started on those parts? Or do you mean you think you know how to do those, and you want to know if you should start doing those?
I'd say getting some DNS servers running dual stack is a sensible place to start. You are going to have to do it at some point. And most of the work in getting your dual stack DNS servers running is getting the IPv6 routes in and out of your network. Having those in place and having the dual stack DNS servers in place will be useful to you regardless of which transition plan you end up deciding on.
should the customer has ipv6 in his adsl router ??
Eventually yes. But a few factors affect how quickly you can get there. If the hardware in place right now supports it, it may just be a configuration change.
or i can use NAT pt at my router the nearest to internet and still the customer uses ipv4
The NAT solutions I know of for this fall into three categories.
- The first category is those that do not involve IPv6 at all. You'll see the terms NAT44, NAT444, CGN applied to this category. You are likely going to need this sort of NAT solution to some extent. But if that is the only connectivity you provide to your customers, you are doing them a disfavour. I have repeatedly advised people to stay away from providers, who provide such a solution as the only connectivity.
- The second category is NAT64+DNS64. In this category your customers will use IPv6 and you will convert it to IPv4 in the NAT. But if want this sort of NAT, you need to have the ADSL connections to the customers somehow supporting IPv6. This class of NAT is applicable if you have working dual stack all the way to your customers, and then run out of public IPv4 addresses.
- The third category is where the customer run IPv4 and the NAT translate this to IPv6 before leaving your network. I haven't seen this sort of NAT advertised from providers, which is why I decided to implement such a system myself. Because traffic is leaving the network as IPv6 there is no need to share addresses, and thus port translation can be avoided, which provides some advantages. If you want to provide this sort of NAT to your customers, you should also provide a NAT44 solution in parallel. If this is the sort of setup you have in mind, maybe we should communicate by email
should i guide my customers to buy a specific adsl routers that support ipv6 ?
That depends on a few things, but certainly for those customers who want to buy an ADSL router with IPv6 support, you should tell them what they need to do and ensure you have sufficient support on your end to make it work.
What other steps you need to take depends on what exactly is the equipment, and who has been providing it.
ADSL modem and router can be two separate pieces of hardware or one integrated piece of hardware. Additionally some users might not have a router, and it is also possible that the customer has ADSL modem build directly into their computer.
Another factor is what your role as ISP has been in providing the hardware in the first place. In some cases customers buy the hardware on their own without involvement of the ISP. In some cases the ISP sell hardware to the customer, when the customer signs up for the service. And in some cases the ISP provide the hardware as part of the subscription. In the last case the customer have a reasonable expectation that the ISP will replace the hardware free of charge, if necessary.
It may be one or two pieces of hardware that need to be replaced, and it may be your responsibility or the customer's responsibility. In any cases I wouldn't rush too much with getting it replaced. You need to ensure that the replacement hardware works well with your network and provide functional dual stack support.
If there is lack of IPv6 support in ADSL modem and/or DSLAM, but the customers have routes with IPv6 support, then a tunnelling solution may be a suitable solution. In that case 6rd may be the best choice of tunnelling solution. AFAIK Free in France and Comcast in US have been doing some large scale deployments of 6rd (but they are now taking the next step). Use of 6rd requires support on both your network and the customers' routers. So if the hardware in place cannot do 6rd already, it may be just as easy to replace those pieces of infrastructure that is IPv4 only as it would be to replace those that need to support 6rd to overcome the limitation on the ADSL hardware.
I'm sure you have had customers who have asked for IPv6 already, those are the first customers you should get the new hardware to (after you have tested it yourself).
also a big problem ,
which is how to edit or reconfigure the tunnel L2TP over ipsec which is impemented between me as an ISP and the PSTN .
what i need to modifiy or should i need another link from pstn to support pstn so as to support ipv6
That question is outside my area of expertise. I hope somebody else in the forum can answer that question.
again im not professional in ipv6 and just need to how to start
I am hoping that my answers will help you make the right decision. I still don't know enough about your network to say for sure exactly which is the right solution for you.