Telecommunications network, Internet, and radio and television networks are currently the three major networks in the field of information technology, from the point of view of the connection and the way of providing services, these three networks have their own characteristics: (1) The traditional telecommunications network (i.e., telephone network) uses circuit switching to realize one-to-one, bidirectional, real-time connection between any two users, and it is mainly used to carry voice services. Since each user occupies a separate communication link, this type of communication is significantly personalized and real-time. In addition, the billing and management mechanism of telecommunication network is relatively urban and perfect, although the traditional telecommunication network has a huge user base, but its link bandwidth is narrow, low utilization rate, and the complexity of connecting signals makes it unsuitable for the transmission of large amount of data. (2) Radio and television networks connect a broadband information source to a large number of users in a one-way, real-time, and one-point-to-multipoint manner, mainly carrying video broadcasting services. Users can only passively choose whether to receive such information (mainly audio and video broadcasts). Since broadcasting uses a point-to-multipoint approach, many users*** enjoy a single information channel without any switching technology, so there is almost no cost to the user, and the operators of broadcasting often report through advertising costs. Radio and television also have a large user base, and HFC (Hybird Fiber_coaxial Cable, fiber optic coaxial cable hybrid) network bandwidth is wide. However, in order to realize two-way transmission services such as data and audio, it is necessary to carry out two-way transformation of the network and increase the data exchange function, which requires high transformation costs. (3) The Internet uses packet switching based on store-and-forward, which mainly carries data communication services. The connection between users can be one-to-one or one-point-to-multipoint. Communication between users can be considered real-time in some cases and non-real-time in most cases. The communication can be two-way interactive or one-way. In Intenet users can *** enjoy the resources, and thus each user needs to pay the cost is relatively low.Internet this flexible communication function, low-cost communication, so that it has been rapid development, popular in the world.Internet's defects are mainly on the bandwidth multimedia business support is not perfect. At present, the three major networks have been integrated and interpenetrated to a certain extent. Users of telecommunication network and cable TV network can access the Internet through ADSL, Cable Modem and other broadband access methods to enjoy the various data communication services provided by the Internet. And IP-TV and other media transmission technologies make the Internet can carry a certain quality of audio and video multimedia services. In principle and technology, the user side of the integrated access equipment, with broadband access network and high-speed fiber optic backbone network, it is possible to video broadcasting, data communications and voice and other three types of business integration in a single network, that is, "triple play". With the continuous development of access technology and network construction, the short-term realization of the so-called "triple play" in the technology is not a big obstacle, but the actual development of the process of conflict of interest between the major networks will become the "triple play" the biggest obstacle to the realization of the concrete, so in a fairly long period of time, the three networks will not be able to achieve the same result. Therefore, for quite a long time, the three networks will maintain the situation of mutual penetration and mutual promotion in the business Notes: Store and Forward (Store and Forward) is one of the most widely used technologies in the field of computer networks, the controller of the Ethernet switch will first cache the packets arriving at the input port, check whether the packets are correct and filter out the conflicting packet errors. After determining that the packet is correct, it takes out the destination address, finds the address of the output port it wants to send through a lookup table, and then sends the packet out. Because of this, the store-and-forward method has a large delay in data processing, which is its shortcoming, but it can detect errors in packets coming into the switch and can support switching between input/output ports at different speeds, which can effectively improve network performance. Another advantage is that this type of switching supports switching between ports of different speeds, keeping the high-speed ports and low-speed ports working together. This is achieved by storing 10Mbps low-speed packets and forwarding them to the port via the 100Mbps rate