IPV6 basic theory and tunnel access 3
IPV6 basic theory and tunnel access to Page 23 Connecting The IP World Stateful approach In a state of DNS server discovery mode, such as through a DHCP server like the DNS server to Sites, such as DNS domain names and search paths to disseminate information to the node. Of course, doing so requires additional servers. Note: The dual stack host in the current circumstances, only the configuration or automatically obtain a Ipv4 Dns server address, Ipv6 addresses can be resolved because it is now Internet, V4 and V6 DNS system is unified. In the Allied Telesyn router, you can configure DNS RELAY, can also tell the DHCP client as a legitimate DNS. 2.6.4. IPv6 DNS DNS In the IPv4 to IPv6 transition process, as the Internet infrastructure of the DNS service should support this network Network protocol upgrades and conversions. IPv4 and IPv6, DNS record format, etc. are different, in order to achieve the IPv4 Between the network and IPv6 network DNS queries and responses can be used DNS-ALG Application Layer Gateway with NAT-PT Approach, the IPv4 and IPv6 networks play a role in translation. For example, IPv4 address mapping domain Use "A" record, and IPv6 use the "AAAA" or "A6" records. Well, IPv4 to IPv6 nodes to send The network DNS query request is "A" records, DNS-ALG put "A" be changed to "AAAA", and send it to IPv6 In the network DNS server. When the server's response when the DNS-ALG to reach, DNS-ALG amended answer to "AAAA" Changed to "A", the IPv6 address into a DNS-ALG of the IPv4 address pool to convert addresses to the IPv4 conversion to Site and the IPv6 address mapping between notification NAT-PT, and to convert this IPv4 address as the analytical results back Back to the IPv4 host. IPv4 hosts to the IPv4 address as the destination address conversion and the actual adoption of IPv6 hosts NAT-PT Communications.
IPV6 basic theory and tunnel access to
Page 24 Connecting The IP World 3. Ipv4-v6 transition 3.1. Transition Theory Phased evolution IPv6 is undoubtedly a great progress, but we must not neglect the past and the future, IPv4 can play. Equipment support a large number of current IPv4, which is run by a phased migration to IPv6 networks to consider one of the reasons. The implementation of IPv6 networks, we must fully utilize the existing network environment, construct the next generation of the Internet, in order to avoid excessive Wasteful investment. IPv4 because of its excellent technical characteristics of the area on the Internet has had tremendous success, the current Internet Is based on IPv4, and can not have them in a short time the transition to IPv6-based network. IPv6 as the Internet The new version of the Protocol and its fundamental purpose is to inherit and to replace IPv4. But from IPv4 to IPv6 is an evolution of Gradual process, rather than the process of radical change. Therefore, completely replace IPv4 in IPv6 before, inevitably, Both of these protocols may be to have a fairly long period of cohabitation. In the IPv6 network popular in the world, before there are always the first with the IPv6 network protocol stack. At this time, These networks like the IPv4 ocean islands. Transition can be divided into two main categories: The first is to address these IPv6 islands to communicate with each other between the issues, The second category is to resolve the IPv6 islands and the IPv4 communication between the sea issues. Solve the transition problem in three ways: dual-stack (Dual Stack), the tunnel (Tunnel) and the translator. IPv6 in the network application layer and transport layer implementation. In addition, use of IPv6, the first batch of equipment also need to IPv4 Backbone support. Therefore, network operators need to consider the need for interoperability between the two protocols. IPv6 has been designed Taking into account the transition and to support the three main technologies: dual-stack (dual-stack), the tunnel (tunneling) and transfer For (translation). The tunnel technology and dual-stack technology has been widely used.
To achieve a smooth transition of IPv4 to IPv6, two sets of issues need to be addressed. One is the sea in the IPv4 network, IPv6 How to communicate between the islands, the main advantage of dual-stack IPv4 and IPv6 networks to establish the tunnel to be achieved; and those The existing IPv4 network and IPv6 network communication problems, the main advantage of dual protocol stacks, protocol conversion, application layer gateways (Application Level Gateway) and in the establishment of IPv6 network IPv4 tunnel to achieve. IPV6 basic theory and tunnel access to No. 25 Connecting The IP World 3.2. Basic Transition Technologies How to transition technology focused on solving the network environment where IPv4 and IPv6 networks to achieve interoperability and the smooth transition The problem, the present basic transition technologies include dual-stack technology and tunneling technology. Dual Stack (Dual Stack) In practice, the most typical is the IETF proposed is called "dual stack" option. Dual-stack refers to a single node to support both IPv4 and IPv6 protocol stacks of two. Because of IPv6 and IPv4 are Function similar to the network layer protocol, both are based on the same physical platform and its load on the transport layer protocols TCP And the UDP and there is no difference, therefore, support dual-stack nodes in both the agreement and support of IPv4 node communication, But also with the support of IPv6 protocol node communication. On the network side, the dual protocol stack is to ensure that IPv6 and IPv4 services can access the key operator networks The edge router should also become a dual-stack routers. In the absence of translator of the network, mobile terminals must be in pairs of co Proposed in order to simultaneously access the stack IPv6 and IPv4 services. Dual-stack work of the program as follows: If the application uses the destination address is the IPv4 address, use the IPv4 protocol; If the application uses the destination address is the IPv4-compatible IPv6 addresses, use the same IPv4 protocols, the The difference is that IPv6 at this time on the package (encapsulated) in the IPv4 them; If the application uses the destination address is a
non-IPv4-compatible IPv6 address, then the time will use the IPv6 Agreement, and probably at this time mechanisms such as the use of tunnels to carry out routing, transmission; If the application uses the domain name as the destination address, then the first time from the DNS server, where the corresponding IPv4/IPv6 address, and then address the situation be handled accordingly. Tunneling technology (Tunneling) The so-called tunnel, that is, one party will be IPv6 packets encapsulated in IPv4 bag, and then be re-opened at the destination, may To the IPv6 packet. Packaged for IPv4 packet source and destination addresses of the tunnel entry and exit of the IPv4 addresses, And header of the "agreement" field is set to 41, indicating that this packet is an IPv6 packet load. As mentioned earlier, in the IPv6 network popular in the world before, there are always some network with IPv6, the first Protocol stack, these networks like the IPv4 ocean islands, the tunnel is through the "submarine" to connect these islands to pass Road, thus lent their names. IPV6 basic theory and tunnel access to P. 26 Connecting The IP World Tunneling technology only requires the tunnel entrance and exit to modify on the other parts not required, thus extremely Easy to implement. As the tunnel link is logical, otherwise known as virtual, therefore, these "islands" formed by the interconnection of networks Network was seen as a virtual network. The need for communication between the IPv6 Native Network or IPv6 nodes need to Communicate with IPv4 nodes, IPv4 protocol was used as a tunnel IPv6 data transmission. Through the tunnel, IPv6 Packet is meaningless as unstructured data, encapsulated in IPv4 datagrams, by being IPv4 network transmission. As the IPv4 Network to IPv6 as unstructured data meaningless data transmission, so do not provide the frame from marking capability, so it is only in the IPv4 connections only when both sides agreed to exchange IPv6 packets, or debit will be IPv6 packets as IPv4 packets and Cause confusion. Network from IPv4 to IPv6 evolution is that these "islands" of gradually expanding to become a "mainland" Process. Protocol Translation (NAT-PT) The final method is to use the address and protocol converter.
Protocol conversion is one of the main proposals Protocol Network Address Translation (NAT). The agreement by using the NAT gateway A kind of IP network address translation to another IP network address. This technique is essentially network address translation (NAT) a simple Expansion, to support only the use of IPv6 equipment and devices to communicate using only IPv4. Protocol conversion drawback is that they often undermine the end-services (such as end to end IP security). This point and IPv4 is similar in the NAT. Meanwhile, the network protocol converter can also cause a potential single point of failure. Therefore, the use of protocol Conversion must be carefully considered, but also to the terminal should be transparent, otherwise the protocol converter will need to do the appropriate changes. And this method requires little in the IPv4 network added between a large number of servers, but also may undermine the openness of the Internet And services for independence. In addition, this implementation is not easy, one of the challenges is how to provide a simple way to convert IPv6 addresses IPv4 addresses, IPv6 The second challenge is to change the subject of the content of IPv4 header. 3.3. Transition Technology Evolution IPv4 to IPv6, to achieve a smooth transition is gradual. Although IETF NGtrans Working Group made a series of IPv4 to IPv6 transition mechanisms and related tools, it should be noted that there is no mechanism to apply to all Case, all of the transition mechanism has its own specific application environments. IPV6 basic theory and tunnel access to Page 27, Connecting The IP World Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Pure IPv4 network IPv4 ocean IPv6 island IPv4 ocean IPv6 Ocean IPv6 Ocean IPv4 island Pure IPv6 Network IPv4 to IPv6 Transition Technology Evolution The table was roughly divided in a smooth transition of IPv4 to IPv6, five stages, and summed up the transition to the evolution of technology, Law. In the early stages of the transition, Internet from IPv4 and
IPv6 ocean island composition of a transitional technology mainly used in IPv4 ocean to achieve communication between the IPv6 islands. With the continued deployment of IPv6 network, IPv4 ocean to Will gradually become smaller, the transition of technology used mainly to solve the IPv4 network and IPv6 network communication problems, while the IPv6 Island will be more and more and eventually the formation of IPv6 ocean, completely replace IPv4.
IPV6 basic theory and tunnel access to Page 28 Connecting The IP World 3.4. IPv6 communication between the islands Manual Tunnel (Configured Tunnels) Manual IPv6 tunnel for IPv4 networks requires frequent communication between the nodes in the case, from the node where the network management Catechism manual configuration. Using this mechanism, the node needs at least a global unique IPv4 addresses, the node's external Routers need to support dual-stack. When the tunnel has to go through NAT domain of such a mechanism may be unavailable. Shortcomings - configuration trouble Automatic Tunnel (Automatic Tunnels) Automatic creation and removal of the tunnel is dynamic, for the IPv4 network, IPv6 traffic between nodes random. Automatic Tunnel IPv4-compatible IPv6 address, called for the automatic tunnel each node has a globally unique IPv4 Address. Use this mechanism to solve the IPv4 address space depletion problem, and does not apply to go through NAT Field situation. Destination address for the IPv4-compatible IPv6 addresses, IPv4 addresses shall be included in the end of the tunnel IPv4-compatible IPv6 address: 0:0:0:0:0:0: a.b.c.d Applies to non-recurring demand for IPv6 nodes connected Benefits - no need to pre-configured tunnels, and easy maintenance Drawback - the destination address is the IPv4-compatible IPv6 addresses requirements Tunnel Broker Tunnel Broker provides a simplified mechanism for the tunnel configuration can reduce the heavy work of the tunnel configuration. With Households through the Tunnel Broker and the ability to easily establish the tunnel IPv6 ISP connections, and thus access to external
IPv6 available Resources. Tunnel Broker required to support dual stack on both sides of the tunnel. 6over4 6over4 does not establish an explicit tunnel, but to use IPv4 multicast mechanisms to achieve a virtual link, by IPv6 multicast addresses mapped to IPv4 multicast addresses to achieve neighbor discovery. This mechanism requires nodes to support multicast, in order to Achieve 6over4 domain and IPv6 routing between networks, requires at least one router interface to support 6over4. 6to4 6to4 is an implementation of IPv4 network, IPv6 tunneling mechanism for inter-domain communication. This mechanism uses a special IPv6 addresses, IPv6 in different domains to establish the tunnel between the egress router, requires that each node must have at least one The world's only IPv4 addresses. 6to4 mechanism will not use the IPv4 routing table in the introduction of new entries in the IPv6 IPV6 basic theory and tunnel access to No. 29 Connecting The IP World Routing table increase of only one table entry, and requires very little configuration management. Destination address for 6to4 addresses, IPv4 addresses shall be included in the end of the tunnel 6to4 Address: 2002: abcd: xxxx: xxxx: xxxx: xxxx: xxxx By 6to4 relay router, so that 6to4 network to connect to a large pure IPv6 network Benefits - no need to pre-configured tunnels, and easy maintenance Drawback - the entire IPv6 network address of the use of special 6to4 3.5. IPv6 and IPv4 ocean island communication between Dual Stack Model Dual Stack Model requires that all nodes are dual stack, IPv4 and IPv6 that does not exist Between the communication problems, but such a mechanism to give an IPv6 node for each assigned an IPv4 address, can not be Solve the IPv4 address space depletion problem. Limited Dual Stack Model Limited Dual Stack Model require servers and routers is still dual stack, rather than the server's host Only need to support IPv6. Such a mechanism could save a lot of IPv4 addresses, but not in pure IPv6 server and pure IPv4 non-direct communication between the servers needed to assist in the completion of the gateway.
SOCKS64 SOCKS64 is the original SOCKS Protocol (RFC1928) extension to IPv4 node can receive connection requests, Can be forwarded to other nodes in IPv4 or IPv6. It does not modify the DNS or do address mapping can be used for IPv6 Pure IPv4 node, the node connectivity, IPv6 network IPv4 nodes and IPv4 networks, IPv6 nodes in a variety of environmental, However, as SOCKS64 the equivalent of high-level protocol gateways, so costly to achieve. SIIT (Stateless IP / ICMP Translation) SIIT [8] is a stateless IP protocol and ICMP protocol conversion, for each group are to be translated. SIIT definition The IPv6 and IPv4 packet header conversion method, but requires a larger alternate IPv4 address pool to allocate IPv4 Address, to the need to communicate with the IPv4 node IPv6 nodes. SIIT can be other mechanisms (such as NAT-PT) with real FP 001 TLA 0x0002 IPv4 addresses SLA ID Port ID Number of bits 313,321,664