ISDN多媒体卡拨号上网的研究与设计

Design and Implementation of Accessing Internet Through an ISDN Multimedia Card

研究在已实现可视通信的ISDN多媒体卡上 ,通过芯片的功能复用 ,设计一个驱动程序模型 ,以实现ISDN多媒体卡的拨号上网功能。简要介绍了ISDN接入因特网的通信协议体系 ,详细探讨了ISDND信道的呼叫过程 ,分析了拨号上网原理及如何与Windows系统的远程访问服务结构相结合。给出了一个基于NDIS标准的ISDN多媒体卡的小端口驱动程序的设计与实现方案。

ISDN can supplied a point_to_point digital connection that can be used to carry multi_traffic including both audio and non_audio signals and perform many operations such as dialing to access the Internet, and video phone especially.In this paper,the special driver model for a video phone ISDN card,which hardware was designed for multiplexed multifunction,to access the Internet is developed.The related ISDN network communication protocols are discussed in detail and the principle of the ISDN multimedia terminal card accessing the Internet under the scheme of MS_Windows RAS (remote access system)is analyzed.In the structure of RAS,the call control in the line is managed by TAPI (Telephone API),and the data transport is achieved by transport drivers.NIC (Network interface card) drivers must complete four functions:to complete the protocols Q.931 and Q.921 in ISDN D channel and control the communication in physical channels;to receive or send data in B channel;to function the interface with TAPI and the management of link layer;to act as the interface with transport drivers by WAN function library and NDIS function library.A miniport driver based on NDIS (network driver interface specification) for the ISDN multimedia card,which enables the card to function as an ISDN modem and a multimedia terminal simultaneously, is developed and the design guide and implementation details are reported.