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If a Layer Two switch does not have the capabilities to run IGMP Snooping, it will be in a position to run CGMP - Cisco Group Membership Protocol. CGMP makes it possible for the multicast router to function with the Layer Two switch to eradicate unnecessary multicast forwarding. CGMP will be enabled on each the multicast router and the switch, but the router's going to do all the work. The router will be sending Join and Leave messages to the switch as necessary. PIM should be running on the router interface facing the switch just before enabling CGMP, as you can see: R1(config)#int e0 R1(config-if)#ip cgmp WARNING: CGMP calls for PIM enabled on interface R1(config-if)#ip pim sparse R1(config-if)#ip cgmp When CGMP is initial enabled on each the multicast router and switch, the router will send a CGMP Join message, informing the switch that a multicast router is now connected to it. This distinct CGMP Join will contain a Group Destination Address (GDA) of 0000.0000.0000 and the MAC address of the sending interface. The GDA is utilized to determine the multicast group, so when this is set to all zeroes, the switch knows this is an introductory CGMP Join, letting the switch know that the multicast router is on the web. The switch makes an entry in its MAC table that this router can be identified off the port that the CGMP Join came in on. For another standpoint, please consider checking out:  [http://www.win.tue.nl/womalapadia/doku.php?id=cosmetic-surgery-do-not-believe-the-hype-812 cosmetic-surgery-do-not-believe-the-hype-812 [WoMaLaPaDiA]] . The router will send a CGMP Join to the switch each minute to serve as a keepalive. A workstation connected to the switch on port /5 now wishes to join multicast group 225.1.1.1. The Join message is sent to the multicast router, but 1st it will pass by means of the switch. The switch will do what you'd anticipate it to do - study the supply MAC address and make an entry for it in the MAC address table as getting off port rapidly /five if there is not an entry already there. (Do not neglect that the MAC address table is also referred to as the CAM table or the bridging table.) The router will then receive the Join request, and send a CGMP Join back to the switch. This CGMP Join will include both the multicast group's MAC address and the requesting host's MAC address. Now the switch knows about the multicast group 225.1.1.1 and that a member of that group is found off port quickly /five. If you believe any thing, you will likely require to explore about  [http://versicherungs-wiki.de/index.php?title=All_You_Need_To_Know_About_Online_Shopping_63888 jump button] . This powerful  [http://www.yhkj288.com/the-actual-deal-with-oxygen-sensors/ The Actual Deal with Oxygen Sensors | yhkj288.com]  link has a few stirring tips for when to deal with it. In the future, when the switch receives frames destined for that multicast group, the switch will not flood the frame as it would an unknown multicast. Alternatively, the switch will forward a copy of the frame to each and every port that it knows leads to a member of the multicast group. Two main rewards of CGMP are the explicit Join and Leave Group messages. In the next part of this BCMSN exam tutorial, nicely take a appear at the Leave Group messages.