Design And Implementation Of VLAN-based IGMP Proxy

In recent years,IP multicast technology has been widely applied in some new applications such as video program broadcasting,network video conferencing,multimedia distance education.IP multicast uses IGMP protocol to manage the multicast group membership between hosts and the neighboring router.The switch between the hosts and the router needs to listen to and forward IGMP messages based on VLAN to implement the constraint control of multicast forwarding.This thesis implements VLAN-based IGMP Proxy technology on the switch to achieve it.In detail,this thesis can be divided into several parts as follows.First,this thesis introduces the related technology,including IGMP protocol,IGMP Snooping technology and IGMP Proxy technology,and then compares IGMP Snooping with IGMP Proxy.Next,this thesis analyzes the networking topology and functional requirements of the IGMP Proxy technology on the switch.Then it designs and implements the VLAN-based IGMP Proxy on the switch,which also resolves some problems existing in IGMP Snooping technology.In the IGMP Proxy technology,in order to reduce the redundancy of IGMP join and leave messages existing in IGMP Snopping switches,it adopt the workaround to intercept and handle those IGMP messages,and sends them to the router only when multicast group membership status in the switch changes.In order to solve the problem that the IGMP Snooping switch relies on the upstream querier to maintain its information of multicast forwarding table,IGMP Proxy switch sends general group queries to hosts to be aware of the multicast group membership status,and sends the group-specific query to the downstream interface when a leave message is received.At the same time,the IGMP Proxy switch has the up-to-date information in the multicast forwarding table,therefore it can directly respond to the router's query rather than forward the query to hosts as if it were an IGMP Snooping switch.Finally,through the packet capture test,we can found that IGMP Proxy can reduce the redundancy of IGMP messages between the router and the hosts,intercept and response to the upstream router query,independently establish and maintain switch multicast forwarding table,and achieve the constraint control of multicast forwarding.At last,this thesis summarizes the problems of IGMP Proxy technology and prospects the future work.