I. Introduction
With the rapid development of network technology and wireless communication devices, people are eager to obtain information from the Internet anytime and anywhere. In response to this situation, the Internet Engineering Task Force (IETF) began to develop a protocol supporting the mobile Internet in 1996, that is, the Mobile IP Protocol [1]. The Mobile IP protocol is a network layer solution that provides mobile functions on the Internet, so that nodes do not interrupt ongoing communication when switching the link. In particular, Mobile IP provides an IP routing mechanism that allows mobile nodes to connect to any link with a permanent IP address.
In order to achieve wireless access over the Internet, each mobile node must be assigned a globally unique TP address. However, due to the surge in the number of Internet users and new application requirements, IPv4 protocol has serious problems such as address shortage and insufficient support for network security and service quality, it cannot meet the needs of future network applications and development.
To this end, IETF has developed the Next Generation Internet Protocol IPv6. IPv6 inherits many features of IPv4, and its huge address space can meet the rapid development of the Internet. It also integrates content such as mobility, security, and service quality. Therefore, IPv6 Protocol [2] is urgently needed on the mobile Internet.
Ii. Mobile IPv6
1 Basic concepts of Mobile IPv6
* Mobile Node: a Node in Mobile IPv6 that can be moved from a connection point of a link to another connection point and can still be accessed through its home address.
* Home Agent: A router on the Home link of a mobile node. When a mobile node leaves his hometown, can the target address of his hometown link be intercepted? Group of the home address of the mobile node, which is forwarded to the transfer address registered by the mobile node through tunnel.
* Correspondent Node: All nodes that communicate with mobile nodes.
* Home Address: a permanent IP Address assigned to a mobile node. It belongs to the Home link of a mobile node. The standard IP routing mechanism sends the Group sent to the mobile node's home address to its home link. When a mobile node has multiple home subnet prefixes on the home link, it can have multiple home addresses.
* Care 0f Address: the IP Address obtained when a mobile node accesses a link in another region. The subnet prefix of this IP address is a foreign subnet prefix. The mobile node can get multiple forwarding addresses at the same time. The forwarding address registered with the home agent is called the primary forwarding address.
* Home Link: A Link corresponding to the Home subnet prefix of a mobile node.
* Foreign Link: Any Link except the home Link.
* Binding: the association between the home address and the transfer address of a mobile node.
2. Working Mechanism of Mobile IPv6
Compared with mobile IPv4, mobile IPv6 has great advantages, so it does not need to be a foreign proxy. It avoids the triangle routing problem, achieves route optimization, and better supports the mobility of mobile nodes.
When a mobile node is located in a home network, it works like a host with a fixed position. The Mobile IP address does not need to perform any special operations. When a mobile node leaves its hometown network and enters a foreign network, its working principle is as follows:
(1) A mobile node obtains one or more forwarding addresses through the conventional IPv6 stateless or stateful automatic configuration mechanism.
(2) After obtaining the transfer address, the mobile node applies to the home agent for registration, and establishes a binding relationship between the home address and the transfer address of the mobile node on the home agent.