Design And Implementation Of Protocol Transform Module And Monitor Of IPv6 Over DVB Sending Gateway

DVB is digital video broadcasting specification; DVB selects MPEG-2 Standard as the way of encoding compression of audio and video. When IP information is packed to MPEG-2 TS and transmitted through DVB channel, the process is called IP over DVB. IPv6 is better than the present main network protocol IPv4 in extension, security and supporting high quality service for users. The background of this thesis is the project of"the application and demonstration research of IPv6 over DVB in distance learning", which is aimed to utilizes the advantage of satellite channel, distributes a great deal of data in a broad area in a low price. This technology is especially suitable for the vast area of middle-western China and promotional for modern distance learning of our country. The main work is:Firstly, the thesis designs and implements the protocol transforming module of gateway on Linux platform. This module use ULE(Unidirectional Lightweight Encapsulation ) as the new way of encapsulation. Contrasting with MPE(Multi-Protocol Encapsulation), of which is used broadly now, ULE reduces 2/3 control fields, and has a better encapsulating efficiency. After comparative research on ULE and MPE in encapsulating space efficiency, delay and lost of packets, the thesis designs and implements the ULE protocol transforming module, which puts IP data into SNDU's payload, adds ULE control fields and destination MAC, after a complete SNDU is segmented and placed into the MPEG-2 TS's payload, the transformation of IP data to MPEG-2 TS is finished. To reduce the difficulty of de-encapsulation and avoid error, this thesis uses some methods to simplify the protocol transform in this procession, such as only one SNDU in every TS, a new SNDU beginning in a new TS, using identifying beginning position for first SNDU segment. The ULE protocol transforming module supports IPv4 and IPv6 double protocol stack, which has the better space efficiency and time efficiency than MPE.Secondly, the thesis designs and implements the monitor of gateway. This module can send monitor messages, receive, parse and show feedback messages. This thesis design 5 monitor messages and 5 feedback messages. Using these messages monitor can configure, require and set PID dynamically through socket, so the monitor can set several PID to transmit the IP data to satellite, and parse the feedback message in real time; monitor the status of the Modem; limit the flow of each PID to prevent the satellite from over pressure in accordance with the supplied band of satellite and the requirement of transmitted data.Finally, the results of testing in laboratory environment and in distance learning application prove the protocol transforming module can run accurately, the ULE is better than MPE in the encapsulating time, and the protocol transforming module and monitor has good stabilization.