Design And Implementation Of Software Of Layer 3 Switch In Community Broadband Network System With Integrated Services

Community Broadband Network System with Integrated Services, which is based on switched Ethernet technology, implement the basic services of normal telephone network, DTV network and computer network. It provides VoIP, DTV, Internet access and etc. for residential users. And the system is for practical research on network merging.This paper introduces the Community Broadband Network System with Integrated Services at first. And then it analyzes the background of the generation of SW1200, which is the layer 3 switch in the core of the system. After the brief introduction of SW1200's hardware and the architecture of its switch chip BCM5690, the paper gives details of the software system implementation in two parts, device driver and user processes, which are based on the software general design.The switch is regarded as a combination of character device and network device in embedded Linux. A modular of device driver is registered in kernel, and the user processes in user space can manage and configure it by calling the interface. Device driver includes hardward modular, interrupt modular, function modular, initializtion/finalization modular, character device interface modular and network device interface modular. User processes includes link scan task, layer 3 unicast task , layer 3 multicast task, management interface and network protocols.The configuration that meets the system requirements of QoS is shown when the switch is used in demo system. And the capabilities and functions of SW1200 is valid in the system by testing.