Clarifications and Updates

IGMP Command Update

IGMP Command Update

The following information updates and clarifies information in Chapter 4, “Multimedia Traffic Control with IP Multicast (IGMP)” in the Advanced Traffic Management Guide—part number 5990-6051, September 2004 edition. Please refer to this chapter for a detailed explanation of IGMP operation.

The 3400cl switches support the following standards and RFCs:

RFC2236 (IGMP V.2, with backwards support for IGMP V.1)

Interoperability with RFC3376 (IGMPv3)

IETF draft for IGMP and MLD snooping switches (for IGMP V1, V2 V3) The 3400cl switches:

Provide full IGMPv2 support as well as full support for IGMPv1 Joins.

Forward packets for the joined group from all sources, including IGMPv3 Joins.

Do not support IGMPv3 “Exclude Source” or “Include Source” options in the Join Reports.

Can operate in IGMPv2 Querier mode on VLANs with an IP address.

IGMP is supported in the HP MIB, rather than the standard IGMP MIBs, as the latter reduce Group Membership detail in switched environments.

Using Delayed Group Flush. This feature continues to filter IGMP groups for a specified additional period of time after IGMP leaves have been sent. The delay in flushing the group filter prevents unregistered traffic from being forwarded by the server during the delay period. In practice, this is rarely necessary on switches such as the Series 3400cl switches, which support data-driven IGMP. (Data-Driven IGMP, which is enabled by default, prunes off any unregistered streams detected on the switch.)

Syntax: igmp delayed-flush < time period >

Where leaves have been sent for IGMP groups, enables the switch to continue to flush the groups for a specified period of time (0 - 255 seconds). This command is applied globally to all IGMP-configured VLANs on the switch. A setting of 0 (zero) disables the feature. (Default: Disabled.)

Syntax: show igmp delayed-flush

Displays the current setting for the switch.

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