What is IPV6 technology?

1 Introduction

The IPV4 address is about to run out, so a discussion that needs to be transferred to IPV6 has not been interrupted in the past few years. IPV4 and IPV6 have significant differences in the message structure, the meaning of the text segment and the address configuration, which brings great difficulties to the operation of the Internet from IPv4 to IPV6. The current access network technology almost all of the applications are built on the IPV4, to be fully converted into IPV6, not overnight work, but a long-term gradual process. Given the need to support the IPV6 business and support the existing IPV4 business, the access network will also support IPV4 and IPV6 operations over a longer period of time. How to realize the transition from IPV4 to IPv6 in the most convenient and effective way is a topic worthy of discussion.

Implementation technology of 2 broadband access network support IPV6

In response to the problem of how IPv4 migrated to IPV6, many research institutes, technical standardization organizations such as IETF,BBF have proposed a variety of solutions, such as double-stack mode, tunnel mode and translation mode. Through the combination and derivation of 3 basic methods, there are many different IPv4 to the IPV6 network, such as DS-LITE,6RD and so on.

2.1 Double Stack Mode

The dual-stack approach requires node devices on the network to support both the IPV4 and IPV6 protocol stacks, and two protocol stacks handle IPV4 messages and IPV6 messages respectively. The dual-stack solution does not save IPV4 addresses, but only reduces the consumption of newly developed businesses to the IPV4 public address. The device supports dual stack, so that operators can open the IPV6 business at any time, so from the consideration of protecting the existing investment of the operator and reducing the perceived impact of the user's business experience, the double stack method is undoubtedly the best solution to the IPV6 network migration.

In the dual-stack mode, similar to the Access network support IPV4 service, there are two basic ways of carrying IPV6 protocol directly through the Data Link layer protocol in the Access network: PPP mode and Ipoe mode. Using PPP to comply with operators ' habits can reduce the pressure of network upgrade.

There are two forms of access to the IPV6 network via PPP:

(1) RG device with support for IPV6 PPP dialing. RG devices connect to the service via PPPV6, while RG provides connectivity for devices in a broadband customer network by routing.

(2) Each terminal/host device initiates its own PPPV6 dial-up connection to the service provider network. In this case, the network terminal work in the bridge mode, the same broadband client network within the terminal/host is independent, it is difficult to communicate with each other.

As can be seen from the figure, the main work of PPP access to the IPV6 network is done by the two endpoints of the PPP link (RG or host at one end, BNG at one end), and the Intermediate Access node device and the two-layer aggregation device are fully transmitted.

When the access network device supports the IPV6 protocol through the IPOE mode, the address acquisition and automatic configuration of the RG device, the three layer protocol-aware function of the Access node device (including some domains of the IPV6 protocol, the processing of the ICMPV6 protocol message, and the security function of the IPV6 service) need to be solved.

2.2 Tunnel mode

Tunneling Technology (tunneling) is a way of transmitting data between networks by using the infrastructure of the internetwork. The data (or payload) that is passed by using a tunnel can be a data frame or package of different protocols. The tunneling Protocol re-encapsulates the data frames or packets of other protocols and sends them through the tunnel. The new frame header provides routing information to pass the encapsulated payload data over the Internet.

The Ipv4/ipv6 tunnel can be divided into two major categories, namely the IPV6 over IPv4 Tunnel and the IPv4 over Pv6 tunnel.

(1) IPv6 over IPv4 Tunnel

Before the IPV6 network completely replaced the IPV4 network, the first access devices with IPV6 protocol stacks (including RG and access node devices) became IPV6 "islands" in the IPv4 ocean. The purpose of the IPV6 over IPv4 tunnel technology is to use the existing IPV4 facilities to serve the IPV6 host, enabling each of the scattered IPv6 "islands" to communicate with each other across the IPV4 network. When the IPV6 message passes through the IPV4 network, no matter which tunneling mechanism needs to carry out the "packet-unpacking" process, that is, the tunnel endpoint at the sending end wraps the IPV6 message in the IPV4 packet, treats the IPV6 packet as the payload data of IPV4 and sets the Protocol field of the IPV4 header to 41. To indicate that the payload of the IPV4 packet is a IPV6 package, and then the package is delivered on the IPV4 network. When the IPV4 package with the Protocol field labeled 41 reaches the tunnel endpoint at the receiving end, the endpoint removes the IPV4 header of the package and takes out the IPV6 package to continue processing.

IPV6 over IPV4 tunneling technology includes GRE tunneling, hand-configured tunneling, automated tunneling using IPV4-compatible addresses, 6over4 technology, 6to4 technology, ISATAP technology, Teredo technology, and 6RD technology.

6RD (RFC5569) is short for IPV6 rapid deployment (IPV6 Rapid Deployment) and is a RFC3056 network transition technology scheme developed on the basis of 6to4 (IPV6). 6RD provides IPV6 access to users who are willing to use IPV6 by adding 6RD-BR to existing IPv4 networks, and IPv6 tunneling between 6in4 users ' home gateways and 6RD gateways, enabling the ability to provide IPV4 services on IPV6 networks. 6RD network Architecture.

6RD technology works as follows: 6rd-ce is the 6RD gateway of the user's home to the uplink IPv6 message from the IPV6 host in the user's network, which is directly encapsulated as the payload (RFC4213) of the IPV4 message in its WAN interface. The source address of the outer IPV4 header of the packet is the 6rd-ce WAN interface IPv4 address, which is the IPv4 address of the IPV4 Internet side interface of 6RD-BR. This message uses the same route addressing method as the ordinary IPV4 message on the IPV4 Internet. 6RD-BR after receiving the message, the outer IPV4 packet header is removed, and the IPV6 message sent by the user's host is forwarded into the IPV6 Internet. When 6RD-BR receives a IPV6 message pointing to the IPV6 host in the 6RD user network, the IPV6 message is also encapsulated as a payload of the IPV4 message on its IPv4 Internet side interface. The source address of the outer IPV4 header of the message is the interface address of the IPV4 Internet side of 6RD-BR, whose destination address is the IPV4 address of the 6rd-ce WAN interface connecting the target user network. According to the 6RD user host addressing rules above, the IPV4 destination address can be obtained directly from the IPV4 address field in the IPv6 destination address in the forwarded IPV6 header. 6rd-ce after receiving the message, the outer IPv4 package header is removed, and the IPV6 message is forwarded to the corresponding IPV6 host in the user network.

(2) IPv4 over IPv6 Tunnel

In contrast to the IPV6 over IPv4 Tunnel technology, the IPV4 over IPv6 tunneling technology is the problem of islanding communication in the IPV4 network, which is the solution to the IPV6 protocol stack, which appears later in the development of IPV6 technology.

Ds-lite is a typical IPv4 over IPv6 tunneling technique, which is a combination of "tunneling technology (Ipv4-in-ipv6 Tunneling)" and "Improved NAT technology (indexed by Tunnel-id/ipv6 address Nat table)". Ds-lite Tunnel Technology Works: The user-side equipment IPV4 traffic encapsulated in the IPv6 tunnel, through the operator's IPV6 access network to the "gateway" device after the end of the IPv6 tunnel encapsulation, and then centralized NAT translation, and eventually forwarded to the IPv4 Internet.

The Ds-lite scheme has the B4 and AFTR two basic function modules, ds-lite data forwarding process.

(1) The B4 (Basic bridging Broad Band Element) module can be integrated in a dual-stack home gateway or software deployed on a dual-stack host interface function, and its main role is to establish a aftr tunnel between the IPv6 module, Encapsulate the IPV4 message into the tunnel and forward it.

(2) Aftr (Address Family Transition Router Element) module can be integrated in the carrier network side of the BNG/SR, or the PE router and other devices, its main role is to end the network side IPV6 Tunnel, the IPV4 messages in the The address and port number are translated and forwarded to the IPV4 Internet.

3 new requirements of IPV6 docking network

The processing ability of the access device to the IPV6 message can be divided into three levels, such as transmission, perception and response.

3.1 Transmitting IPV6 messages

When the function of the access device is located on the L2, whether it is the IPV4 message or the IPV6 message, the access device will not detect, perceive and process any of it, only transparent transmission. Access devices can meet this requirement without any upgrade.

3.2 Sensing IPV6 messages

The sense of the access device to the IPV6 message refers to the ability to identify, differentiate IPV6 messages and IPV4 messages, and to perform processing operations such as VLAN tagging, QoS, packet filtering, etc., based on the IPV6 protocol, including but not limited to:

(1) distinguish between IPV4 messages and IPV6 messages, and divide them in different VLANs.

(2) Set different Ethernet priorities for IPV4 messages and IPV6 messages.

(3) Classify business flows based on IPV6 source/destination address, IP protocol type (such as ICMPV6,MLD, etc.), IPv6 priority field (traffic Class), and IPv6 flow tag field (Flow label).

(4) Filter the data frame based on the IPV6 source/destination address.

(5) Speed limit for specific protocol messages (such as ICMPV6, etc.).

(6) The port tag is implemented by DHCPV6 Relay Agent Option18/37 function.

(7) IPv6 controllable multicast function.

3.3 Answering IPV6 protocol messages

Access devices that support the L3 routing feature, especially gateway devices, need to respond to IPV6 protocol messages in the following processing processes: Get/Assign IPV6 addresses, IPv6 route forwarding.

What is IPV6 technology?