Study On The Application Of Stackable VLAN To MAN

Communication network has been changed greatly in recent years, and the telecom network based on circuit switch is combined with computer network based on data services in the service and network field. However, the number of VLAN is limited by the definition for the byte width of VID in VLAN with the development of the MAN. Therefore, many manufactures of network equipment try their best to expend the number of VLAN in different ways.The resource of VLAN ID can not satisfied with the demand of the access layer because of the dramatic increase of users. However, it can be solved by using transmission network with high bandwidth and high quality.A user-defined stackable VLAN is presented in this paper. It can complete the truck of user port and use the resource of system side port reasonably and efficiently without changing users' VLAN IDs, by adding six-bytes long SVLAN to explain the user-defined protocol. The way presented here can not only solve the problem on the number of VID in VLAN, but also fulfill the truck of the user port. That is very meaningful in solving the problem caused by the deficient resource of VID for rapid spread in the network of MAN.Data structure is defined and the flow of program is designed, according to the IEEE standard, and the VxWorks, which is the mainstream real time embedded operating system, is used in software design.The powerful net processor IXP 1200 is used in hardware design, which can make the procession of protocol quick and accurate. Moreover, both programming techniques on microcodes and network processor microcodes are applied successfully, which uses the advantage and characteristic of network processor sufficiently. In the meantime, the switch based on stackable VLAN is put into practice, and test for long and short frames is performed.The results of test show: the truck is realizable after adding the field of SVLAN. Meanwhile, the thread rate of layer 2 isn't influenced and the resource of user VID is protected well. That demonstrates potential applications of the stackable VLAN in Ethernet.