Igmp Snooping Protocol In Epon Realization

EPON (Ethernet Passive Optical Network) was introduced by EFM (Ethernet in the First Mile) in the early of 2001. EPON is designed to carry Ethernet frames at standard Ethernet rates (defined by IEEE 802。3 protocol) with a point-to-multipoint fiber infrastructure. In order to manage Broad-Band multimedia operation, it is necessary to study the question of realizing multicast in EPON for the technology of multicast is an effective way of saving the bandwidth and receding the network load. As usual, the multicast means IP multicast, it is realized on the third layer; In EPON system ,OLT and ONU can be seen as Ethernet switch essentially, as they are the equipment of the second layer. If Multicast packets and broadcast packets are not differentiated, OLT will broadcast the multicast packets when it has received the multicast packets, which has not only wasted bandwidth, but also caused multicast packets flooding and affected the normal operation.Introducing IGMP Snooping protocol into the EPON will certainly make more development in the application of EPON. In order to support broadband multimedia services in EPON, it is necessary to study on supporting multicast in EPON, because multicast saves bandwidth, reduces the network load. Usually it says that multicast is the IP multicast, which is realized in the third layer; In EPON system, OLT and ONU can essentially be recognized as Ethernet switches, which all belong to the second floor devices. They recognize multicast packet and broadcast packets indiscriminately, OLT directly broadcasts the packet after receiving the multicast packets (a phenomenon known as the Pan-stream), it will not only waste a lot of network bandwidth, causing the broadcast storm ,and also affect the normal operations. Therefore, there is an urgent need to realize the multicast data support in EPON systems. The second layer multicast technology introduced into EPON must make greater development in the application level of EPON. The study has been carried out in home and abroad , which has achieved some results, and the multicast technology has been widely studied and applied. In this article we focus more on the realization of the way how to implement multicast in EPON protocol with embedded software.The article divides into five parts: The first part tells of the feature and structure of EPON and the background and the meaning of introducing IGMP Snooping protocol into the EPON. The second part discusses the relationship of the IGMP protocol on the third layer and the IGMP Snooping protocol on the second layer. The third part expatiates the designing plan of each module including task-creation module,message-send module to realize the IGMP Snooping protocol. The forth part narrates the mode of debugging the programmer in the Tornado environment and the analysis of the result. The fifth part is the summing-up of the whole graduate design.