#|
If a site has a AAAA record, and you have a dual stack setup, you will typically connect to ipv6 first then ipv4. Three main options are available for migration to IPv6 from the existing network infrastructure: dual-stack network, tunneling, and translation. Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
How to tell an IPV6 address is static or dynamic? Using the tunneling option, organizations build an overlay network that tunnels one protocol over the other by encapsulating IPv6 packets within IPv4 packets and IPv4 packets within IPv6 packets. The advantage of this approach is that the new protocol can work without disturbing the old protocol, thus providing connectivity between users of the new protocol. Tunneling has two disadvantages, as discussed in RFC Address Family Translation AFT , or simply translation, facilitates communication between IPv6-only and IPv4-only hosts and networks whether in a transit, an access, or an edge network by performing IP header and address translation between the two address families.
AFT is not a long-term support strategy; it is a medium-term coexistence strategy that can be used to facilitate a long-term program of IPv6 transition by both enterprises and ISPs.
Translation offers two major advantages, as discussed in RFC As discussed, AFT offers benefits over the other available IPv6 migration and transition technologies.
Figure 2 and Table 1 summarize various scenarios supported by translation. AFT can be achieved using either of the following two technologies:. All viable translation scenarios are supported by NAT64, and therefore NAT64 is becoming the most sought translation technology. Table 2 and Figure 3 compare stateless and stateful NAT Figure 4 shows a typical greenfield IPv6-only network: for example, an enterprise, mobile service operator, broadband service provider, or ISP network.
The primary requirement of such a greenfield network deployment is seamless connectivity for IPv6-only hosts to reach both IPv6 and IPv4 Internet and network content. However, because the server has only an A record for example. The IPv6-only host connects to the service hosted by example. The synthesized AAAA record is transparent to the host, and it appears as if example. The IPv4 server hosting service offered by domain example.
After translation, the IPv6 packets are forwarded using normal IPv6 route lookup. Figure 10 shows a typical existing IPv4 content provider network: application, e-commerce, social networking, etc.
Thus, IPv4 address The IPv6-only host connects to the service hosted by example-v4. The IPv4 server hosting service offered by domain example-v4. Thus, transparent communication is established between an IPv6-only host and IPv4-only server using stateful NAT64 translation at the content provider's edge.
Scenarios 2 and 6 are extensions to scenarios 1 and 5 in RFC discussed earlier in this document and can be treated as the reverse of scenario 3.
The primary requirement of such a greenfield network deployment is the capability to provide services transparently to both IPv6 and IPv4 users. This requirement is identified as scenarios 2 and 6 in this document and can be met by using stateful NAT64 technology provided by Cisco ASR Series routers.
Also register IPv4 address The DNS authoritative server responds with an A response for domain example-v6. The IPv4-only host connects to the service hosted by example-v6. The IPv6 server hosting service offered by domain example-v6.
After translation, the IPv4 packets are forwarded using normal IPv4 route lookup. Thus, transparent communication is established between an IPv4-only host and an IPv6-only server using stateful NAT64 translation at the content provider's edge.
Figure 17 shows the configuration for stateful NAT64 translation. Connect and share knowledge within a single location that is structured and easy to search. IPv4 has no techniques for talking to IPv6. They are entirely different network stacks, although there are a lot of similarities. IPv6 does have a representation for native IPv4 addresses so they can be routed appropriately.
Essentially, the IPv6 country would have limited access from other countries using IPv4. Gateways could enable access to email, web sites, and other services, but this would need to be handled on a roughly case by case basis. The providers of cable modems and other such equipment are scrambling to be able to provide IPv6 capability. In part this is because they will need to provide dual stacks on hardware with limited memory capacity.
Different techniques will be needed to secure networks from the external access. IPv4 and IPv6 are two entirely different protocols, although they do the same thing actually, IPv6 does a lot more, but that's another story. This means that if someone is using only IPv6, they will not be able to "talk to" someone else whos is using only IPv4 and vice versa.
In your scenario, this would effectively "cut off" the IPv6-country from the rest of the world and the inhabitants' computers would only be able to communicate inside the country's borders.
In practice, some address translation mechanics would probably be used which could allow at least some traffic to go through. Most IP transit providers nowadays will provide dual-stack, but with mobile and broadband ISPs the picture is often a lot less rosy. So anyway back to the question of of interoperation. Since it is clear that in the real world IPv4 isn't going away any time soon a variety of mechanisms have been devised to try and bridge the gap.
The first and simplest is just a point to point tunnel, such tunnels can be pretty reliable and with the right tunneling technologies can work behind NAT. The problem is of course the tunnel has to terminate somewhere. The next is 6to4. Packets from 6to4 clients are encapsulated in IPv4 and can be sent to other 6to4 clients or to a relay anycast address.
Unfortunately it doesn't work behind NAT. The next thing to mention is teredo. Unfortunately it is pretty fragile and often fails. Also due to the way teredo finds relays it will only work if the IPv6 host responds to pings. Also ISPs mostly don't seem to have stepped up to the plate and deployed 6to4 and teredo relays in their networks, so 6to4 and teredo traffic ends up going via one of a handful of networks who provide relays for the internet in general.
This often ends up limiting performance. Teredo and 6to4 have largely failed to achive increases in the ipv6-capable client base.
It has become clear that while IPv6 deployment is growing, the burden of interoperability will have to be shouldered by those wanting to run IPv6 only networks. Which brings us round to how they can do that. On the server side NAT based approaches can also be possible, but they have the problem that you still need an IPv4 address for each server which defeats most of the point of running an IPv6 only network. Another option is reverse proxies which can direct traffic based on application layer headers.
0コメント