101Configuring IGMP (available only on theS5500-EI)OverviewAs a TCP/IP protocol responsible for IP multicast group member management, the Internet GroupManagement Protocol (IGMP) is used by IP hosts and adjacent multicast routers to establish and maintaintheir multicast group memberships.The term "router" in this document refers to both routers and Layer 3 switches.The term "interface" in this chapter collectively refers to Layer 3 interfaces, including VLAN interfacesand Layer 3 Ethernet interfaces. You can set an Ethernet port as a Layer 3 interface by using the portlink-mode route command (see Layer 2—LAN Switching Configuration Guide).IGMP versions• IGMPv1 (defined in RFC 1112)• IGMPv2 (defined in RFC 2236)• IGMPv3 (defined in RFC 3376)All IGMP versions support the Any-Source Multicast (ASM) model. In addition to the ASM model,IGMPv3 can directly implement the Source-Specific Multicast (SSM) model. IGMPv1 and IGMPv2 mustwork with the IGMP SSM mapping function to implement the SSM model.For more information about the ASM and SSM models, see "Multicast overview."Introduction to IGMPv1IGMPv1 manages multicast group memberships mainly based on the query and response mechanism.All multicast routers on the same subnet can receive IGMP membership report messages (often called"reports") from hosts, but the subnet needs only one router to send IGMP query messages (often called"queries"). The querier election mechanism determines which router acts as the IGMP querier on thesubnet.
