Allied Telesis 2.6.1 manual Disable Igmpsnooping

98 AT-8800 Series Switch User Guide

out all ports. IGMP snooping is independent of the IGMP and Layer 3 configuration, so an IP interface does not have to be attached to the VLAN, and IGMP does not have to be enabled or configured.

IGMP snooping is enabled by default. To disable it, use the command:

DISABLE IGMPSNOOPING

Disabling IGMP snooping may be useful if filters are used extensively, because IGMP snooping uses a Layer 3 filter. When IGMP snooping is disabled, this filter becomes available. See “Hardware Packet Filters” in the Switching chapter of your Software Reference for information about filters. Note that multicast packets will flood the VLAN when IGMP snooping is disabled.

IGMP is used in conjunction with limited static multicast settings, or with DVMRP or PIM Sparse Mode for full multicast support (IP Multicasting chapter in the Rapier Switch Software Reference).

IGMP is enabled and disabled using the commands:

ENABLE IP IGMP

DISABLE IP IGMP

IGMP snooping is then enabled or disabled on a VLAN using the commands:

ENABLE IP IGMP INTERFACE=interface [DLC=1..1024]

DISABLE IP IGMP INTERFACE=interface [DLC=1..1024]

The switch will snoop IGMP packets transiting the VLAN and only forward multicast packets to the ports which have seen a membership report from network devices connected to those ports, instead of being forwarded to all ports belonging to the VLAN.

The command:

SET IP IGMP TIMEOUT=1..65535 QUERYINTERVAL=1..65535

sets operational parameters for IGMP. The QUERYINTERVAL parameter specifies the time interval, in seconds, at which IGMP Host Membership Queries are sent if this switch is elected the designated router for the LAN. The default is 125.

The TIMEOUT parameter specifies the longest interval, in seconds, that a group will remain in the local group database without receiving a Host Membership Report. The default is 270. If a value is specified for QUERYINTERVAL without specifying a value for TIMEOUT, TIMEOUT is calculated as 2*(QUERYINTERVAL + 10). The 10 seconds is the variation that hosts use when sending Host Membership Reports. If a timeout interval is specified, it will override any calculated value.

The command:

SHOW IP IGMP [COUNTER] [INTERFACE=interface]

displays information about IGMP, IGMP snooping, and multicast group membership for each VLAN-based IP interface (Figure 21, Table 21 on page 99).

Software Release 2.6.1 C613-02039-00 REV A