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IGMP/VLAN Configuration Screen
Layer 3 Extensions Menu Screens 9-3
9.2 IGMP/VLAN CONFIGURATION SCREEN
When to Use
The IGMP/VLAN Configuration screen, Figure 9-2, is used to enable or disable IGMP (Internet
Group Management Protocol, RFC 2236) on selected VLANs, or globally on all VLANs that are
available.
IGMP provides a solution for handling multicast streams in layer 2 switching devices. IGMP is for
hosts on multi-access networks to inform locally attached switches of their Multicast group
membership information. This is performed by hosts multicasting IGMP Host Membership
Reports. Multicast switches listen for these messages and then passes them to the router. This
allows distribution trees to be formed to deliver multicast datagrams.
Information from the IGMP packets is used to send the multicast stream only to the end stations
that request it.
IGMP is enabled or disabled by VLAN, not port-by-port.
The following multicast routing protocols are transparently supported and are used only to detect
the location of routers (See the Release Notes for any changes or additions to this list):
• DVMRP (Distance Vector Multicast Routing Protocol, RFC 1075)
• PIM (Protocol Independent Multicast) versions 1 and 2
• CBT (Core Based Trees)
• MOSPF (Multicast OSPF, RFC 1583)
For additional information about IGMP, refer to Appendix B.
NOTE: Certain versions of firmware will not allow the switch to be a querier. Please
check your release notes for further information. Refer to RFC 2236, Section 8, for more
information on IGMP.
NOTE: The IGMP/VLAN Configuration screen does not display when the operational
mode of the device is set to SECURE FAST VLAN.
Section 4.2.9 provides instructions for setting the operational mode.