3Com 3C17300-US Implementation Manual

Contents

113IGMP snooping A mechanism performed by an intermediate device, such as a Layer 2Switch, that optimizes the flow of multicast traffic. The device listensfor IGMP messages and build mapping tables and associatedforwarding filters, in addition to reducing the IGMP protocol traffic.Internet GroupManagementProtocolInternet Group Management Protocol (IGMP) is a protocol that runsbetween hosts and their immediate neighboring multicast routers. Theprotocol allows a host to inform its local router that it wishes to receivetransmissions addressed to a specific multicast group. Based on groupmembership information learned from the IGMP, a router is able todetermine which if any multicast traffic needs to be forwarded to eachof its subnetworks.Intranet An Intranet is an organisation wide network using Internet protocolssuch as web services, TCP/IP, HTTP and HTML. An Intranet is normallyused for internal communication and information, and is not accessibleto computers on the wider Internet.IP Internet Protocol. IP is a layer 3 network protocol that is the standardfor sending data through a network. IP is part of the TCP/IP set ofprotocols that describe the routing of packets to addressed devices.IPX Internetwork Packet Exchange. IPX is a layer 3 and 4 network protocoldesigned for networks that use Novell ® Netware ®.IP address Internet Protocol address. A unique identifier for a device attached to anetwork using TCP/IP. The address is written as four octets separatedwith periods (full-stops), and is made up of a network section, anoptional subnet section and a host section.Jitter An expression often used to describe the end-to-end delay variationsduring the course of a transmission. See also latency.LAN Local Area Network. A network of endstations (such as PCs, printers,servers) and network devices (hubs and switches) that cover a relativelysmall geographic area (usually not larger than a floor or building). LANsare characterized by high transmission speeds over short distances (upto 1000 m).LLC Logical Link Control. A sublayer of the IEEE data link layer that islocated above the MAC sublayer. The LLC sublayer is responsible forMAC sublayer addressing, flow control, error control, and framing.dua1730-0bAA03.book Page 113 Monday, July 11, 2005 11:14 AM