/mcp2 01-00-5e-00-00-02 # 1/9 2 01-80-c2-00-00-00 # 1/9 2 01-80-c2-00-00-01 # 1/9 3 01-00-0c-cc-cc-cc # 1/9 3 01-00-0c-cc-cc-cd # 1/9 3 01-00-0c-dd-dd-dd # 1/9 3 01-00-5e-00-00-01 # 1/9 3 01-00-5e-00-00-02 # 1/9 3 01-80-c2-00-00-00 # 1/9 Do you wish to continue y/n [n]? y Total Matching CAM Entries Displayed = 22 The client sends a IMPG Leave message to 224.0.0.2. The switch intercepts it and sends an IGMP Query on the port on which he receives the leave. The following is debug output on the switch: MCAST-IGMP-LEAVE:Recvd leave on port 3/2 vlanNo 3 MCAST-IGMP-LEAVE:router_port_tbl[vlanNo].QueryTime = 0 MCAST-IGMP-LEAVE:deletion_timer = 1 MCAST-SEND:Transmitting IGMP Mac Based GS Query msg on port 3/2 vlanNo 3 MCAST-SEND: Transmit Succeeded for IGMP Group Specific Query msg on port 3/2 vlanNo 3 2. Because no response was received, the Catalyst forwards the IGMP Leave message to the router, as shown below. MCAST-TIMER:IGMPLeaveTimer expired on port 3/2 vlanNo 3 GDA 01-00-5e-0a-0a-0a MCAST-TIMER:IGMPLeaveTimer expiry: Transmit IGMP Leave on port 3/1 vlanNo 3 MCAST-SEND:Transmitting IGMP Leave msg on port 3/1 vlanNo 3 MCAST-SEND: Inband Transmit Succeeded for IGMP Leave Message on port 3/1 vlanNo 3 3. The router receives an IGMP Leave message, so it sends a CGMP Leave message to the switch and also deletes the group from its IGMP group list. Below is the debug command output on the router.On the router IGMP: Received Leave from 10.200.8.108 (Fa0.3) for 239.10.10.10 IGMP: Send v2 Query on Fa0.3 to 239.10.10.10 IGMP: Send v2 Query on Fa0.3 to 239.10.10.10 CGMP: Sending Leave on Fa0.3 GDA 0100.5e0a.0a0a, USA 0000.0000.0000 IGMP: Deleting 239.10.10.10 on Fa0.3 4. CGMP Traces and Configuration Frame 1 Frame 1 is a CGMP Join frame to GDA 00-00-00-00-00-00. It is used to add the router port to the router port list. ISL: ----- ISL Protocol Packet ----- ISL: ISL: Destination Address = 01000C0000 ISL: Type = 0 (Ethernet) ISL: User = 0 (Normal) ISL: Source Address = 8C958B7B1000