Application of IPv6 Multicast Technology in Distance Education (1)

I. Question proposal

With the development of computer technology, network technology and multimedia technology, modern distance education achieves a networked and real-time interactive teaching form. In particular, the development of Internet technology has promoted the emergence of many network universities and network schools. The number of educational websites is also growing rapidly, and the number of online teaching resources is also growing, it can be said that modern distance education has entered a period of vigorous development. However, due to network bandwidth and transmission mechanisms, most of the content on educational websites currently focuses on static teaching materials, but few video and audio streaming media teaching information, even if some websites support online browsing and downloading of video and audio streaming media content, it is difficult to achieve two-way interaction because of the slow network transmission rate, so the effect is not satisfactory. This has largely weakened the attractiveness of online education to many learners, and thus greatly reduced the quality and effectiveness of distance education.

The emergence of IPv6 not only solves the problem that 1Pv4 address space is almost exhausted, but also improves the basic Header Format of IP data packets. The most important thing is that IPv6 can better support multicast, video and audio streaming media teaching information can be smoothly transmitted without a significant increase in network bandwidth, which reduces network bandwidth and network load, in addition, it provides personalized and lifelong education anytime, anywhere. Therefore, the IPv6-based Multicast technology provides a better way to solve the above problems of distance education.

II. Introduction to IPv6 and Multicast Technology

(1) IPv6 Performance Overview

IPv6 is proposed to solve the problem that IPv4 address space is nearly exhausted. Its performance mainly includes:

1. Huge address space

IPv6 uses a 128-bit IP address, that is, IPv6 provides 2128 address spaces. In the image, there will be more than 1000 IPv6 addresses per square meter on the earth.

2. Simple addressing and routing Methods

The IPv6 address type is based on a layered network topology. This structure is of great benefit to network security. At the same time, IPv6 improves the basic Header Format of the IP packet. It has only 6 domains and 2 address spaces. This simplified header not only contains a small number of fields, but also has a fixed header length, which makes the hardware implementation of the router easier. In route analysis, IPv6 does not split data, further reducing the routing load.

3. Better security features

IPv6 provides several important security functions. IPv6 specifications specify "Authentication Header" and "encapsulation security net load ". The authentication function provides a mechanism for the recipient to confirm that the source IP address of the IP Group is correct and its content is not modified during transmission; the "encapsulation security net load" function ensures that only valid recipients can read the content of the IP Group. This identity authentication method can effectively prevent network eavesdropping, so as to ensure the security of users and systems, and to a certain extent, it can prevent hackers from exploiting network protocol vulnerabilities for cracking activities.

4. Support for Multicast

IPv6 provides a new cluster communication address-multicast. multicast allows routers to copy data packets to multiple data channels at a time using the multicast capability of the IP network, realize one-to-multiple-point or multi-to-multiple-point data transmission. Multicast can greatly save network bandwidth, because no matter how many target addresses there are, only one packet is transmitted on any link of the network, thus reducing network load.

(2) Introduction to multicast Technology

1. Concept of Multicast

Multicast is a network technology that allows one or more senders (Multicast sources) to send a single packet to multiple recipients (one-time and simultaneous. Multicast sources send data packets to multicast group members based on IP addresses. The host in the multicast group can be in the same physical network or from different physical networks (the multicast router must be supported ).

2. Key Technologies for multicast implementation

Multicast technology is applicable to data transmission services from one point to multiple points or from multiple points to multiple points. The basic principle of multicast implementation is that it relies on the IP protocol to complete multicast. IP multicast forces the network to copy information packets at the forks of the data distribution tree. IP multicast is implemented in three parts: Addressing, multicast member management, and multicast routing protocol.

Multicast addressing: IPv6 reserves a certain address space for multicast. Its 8-bit address height is "11111111", followed by the 120-bit multicast group ID. This address is only used as the target address of the multicast packet. The source address of the multicast packet can only be a unicast address. The sender only needs to send data to the multicast address, so that the sender can send user data from multiple locations without knowing any information of the receiver.

Multicast member management: multicast uses the IGMP (Internet Group Manager Protocol) Protocol to dynamically register users. Establishes and maintains the relationship between multicast group members through the IGMP protocol between the host and the multicast router. The multicast forwarding router uses the IGMP protocol to check whether a multicast group's receiver exists on the network segment connected to each interface, that is, the group members. If a member is present, the multicast router forwards the multicast packet to this network segment. If no, the router stops or does not forward the packet to save bandwidth.

Multicast Routing Protocol: the multicast routing protocol is used to establish and maintain Multicast Route tables to make full use of bandwidth. Multicast Routing Protocols can be divided into dense mode and sparse mode. The Multicast Routing Protocol in dense Mode means that multicast members are concentrated on the entire network, that is, many subnets contain at least one member, and the bandwidth is abundant. It is not applicable to large-scale networks. The Sparse Mode is suitable for scenarios where multicast members are evenly distributed across the network and bandwidth is not necessarily sufficient.