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  • IGMP Snooping with Multicast Message Filtering or Pruning

    Until recently, Internet Group Management Protocol (IGMP) has been only a Layer 3 protocol used by IPv4 systems to report IP multicast memberships to neighboring multicast switches and routers (Also See Below, for a new GarrettCom technology--IGMP-L2 for Layer 2 Magnum 6K Switches). IGMP is a standard defined in RFC1112 for IGMPv1, in RFC2236 for IGMPv2 and in IGMPv3.  It specifies how a host can register a router to receive specific multicast traffic.

    IGMP snooping, as implied by the name, is a feature that allows an Ethernet switch to "listen in" on the IGMP conversation between hosts and routers. When a Switch hears an IGMP report from a host for a given multicast group, the switch adds the host's port number to the IGMP list for that group. And, when the switch hears an IGMP leave, it removes the host's port from the IGMP list.

    A key feature of the MNS-6K software, crucial for today’s Industrial Ethernet protocols and Integrated Video applications, is IGMP Snooping.  IGMP (Internet Group Management Protocol) is important in industrial networking, and may be used with some field bus protocols over Ethernet such as Allen-Bradley’s EtherNet/IP, Foundation Fieldbus HSE (High Speed Ethernet), and Siemens’ Profibus.  

    These industrial Ethernet protocols make extensive use of publisher/subscriber communications models by multicasting packets onto the network that could inundate a large network with heavy traffic.  IGMP Snooping provides the ability to “prune” multicast traffic so that it travels only those end destinations that require that traffic.  In effect, it yields the best of both unicast and multicast addressing, and reduces the amount of traffic on the Ethernet LAN. 

    Integrated Video networks are designed to meet the requirements of video surveillance applications. The video-over-Ethernet traffic stream from the cameras is combined with other typical LAN data traffic, enabling one common LAN system to be used for operations traffic as well as for video surveillance. 

    Besides IGMP Snooping, the network management requirements for Integrated Video Networks often include Spanning Tree Protocol for redundancy, tagged VLANs for multi-switch security,  Port Security for intruder protection, and SNMP access control. The Switches are often environmentally hardened.  Typical applications are in public and private buildings, incident management along freeways and at city traffic intersections, and in transportation facilities such as airports, railways and light rail stations.

    For an overview tutorial by iMPath of IGMP used in multicast networks, click on the following link (may take a few moments to load).      IGMP Tutorial  

    MNS-6K Software Feature for IP Video--IGMP-L2
    Multicast for streaming data has become increasingly important because IP video surveillance is increasingly desired. A new GarrettCom technology (patent # 7,512,146) enables multiple streams of data to be efficiently managed using only Layer 2 Ethernet switches.  This MNS-6K feature will simplify many large LANs that serve applications with streaming data such as video surveillance.  Previously, this capability was available only with LANs incorporating complex Layer 3 switches and routers with IGMP (Internet Group Management Protocol).

    Read technical brief of IGMP-L2