| Access switch is a switch device applied in access layer which is mainly deployed in medium/small-sized enterprise network,campus network,government network and other similar access scenarios.With the extending demands of services in the access application,access switch is required to provide more diverse and power functions.At present in the market,there are various types of access switch that can provide data forwarding,VLAN dividing,broadcast storm control and Layer 2 multicasting.In addition,there are some kinds of device provide support for IP routing,DHCP,Layer 3 multicasting and network management.However,in some special industry access scenarios,access switch is required to provide some customized functions for some specific needs.Meanwhile,considering the upgrading of terminal equipments and changes in requirements in the future,it is required that the functions can be scalable and extensible.Throughout filtering all the access switches in the market today,none of them can meet these specific needs.Based on the requirements of access switch stated above,the motivation of this paper is to develop a kind of dedicated access device applied in specific scenarios that can not only provide general functions of access switch but also support the realization of user customized function and the ability to extend or shrink these functions according to the changes in requirements.The main aim of this paper is to design an overall scheme of access switch software based on the analysis of functionality and performance requirements for access switch software.According to the designed overall scheme,the design and implementation of network management,DHCP and multicast functions are completed.Meanwhile,the testing environment is developed to verify the correctness of the overall scheme design and each function implementation.Firstly,we analyze the functionality and performance requirements of dedicated access switch software in this paper,and design the overall scheme of access switch software based on embedded Linux operating system.In specific,the software is divided into five functional modules which are DHCP,unicast routing,multicast,network management and device identification,respectively.Secondly,based on the research of SNMP system,we develop the SNMP agent software and SNMP management software according to the management requirement of access switch.By building a test environment on switch development board,we verify the correctness of network management function.Then,according to the DHCP protocol mechanism,we develop a DHCP server program.By building a network test environment,we verify the correctness of DHCP function on the Linux operating system.Finally,based on the in-depth study of the mechanisms of IGMP and PIM-SM protocols,the multicast operating mechanism based on Linux operating system is proposed and the multicast protocol processing program is developed.By building the network test environment,we verify the correctness of multicast function on the Linux operating system.In conclusion,this paper designs an overall scheme of access switch software and verify the correctness and feasibility of the proposed scheme,which lays a solid technical foundation for the development of the other functional modules. |
