HP 6120XG HP ProCurve Series 6120 Blade Switches Multicast and Routing Guide - Page 33

Multimedia Traffic Control with IP Multicast (IGMP) How IGMP Operates IGMP Function Available With IP Addressing Available Operating Differences Without an IP Address Configured on the VLAN Without IP Addressing? Configure IGMP traffic forwarding to normal or Yes high-priority forwarding. None Age-Out IGMP group addresses when the last Yes Requires that another IGMP device in the VLAN has an IP IGMP client on a port in the VLAN leaves the address and can operate as Querier. This can be a multi- group. cast router or another switch configured for IGMP operation. (ProCurve recommends that the VLAN also include Support Fast-Leave IGMP and Forced FastLeave IGMP (below). Yes a device operating as a backup Querier in case the device operating as the primary Querier fails for any reason. Support automatic Querier election. No Querier operation not available. Operate as the Querier. No Querier operation not available. Available as a backup Querier. No Querier operation not available. Automatic Fast-Leave IGMP Fast-Leave IGMP. The switches support Data-Driven IGMP ("Smart" IGMP), and Fast-Leave is enabled in the default configuration. They drop unjoined mulitcast traffic except for always-forwarded traffic toward the Querier or multicast routers, and out of IGMP-forward ports. These switches electively forward joined multicast traffic. When unregistered multicasts are received the switch automatically filters (drops) them. Thus, the sooner the IGMP Leave is processed, the sooner this multicast traffic stops flowing. Automatic Fast-Leave Operation. If a switch port has the following characteristics, then the Fast-Leave operation will apply: 1. Connected to only one end node 2. The end node currently belongs to a multicast group; i.e. is an IGMP client 3. The end node subsequently leaves the multicast group Then the switch does not need to wait for the Querier status update interval, but instead immediately removes the IGMP client from its IGMP table and ceases transmitting IGMP traffic to the client. (If the switch detects multiple end nodes on the port, automatic Fast-Leave does not activate-regardless of whether one or more of these end nodes are IGMP clients.) 2-14