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DES-7200 Configuration Guide Chapter 8 IGMP Snooping
Configuration
8-5
8.1.4.3 Leaving the Multicast Group
When leaving the IP multicast group, the host notifies the multicast router of the
leave event by sending the IGMP leave group packets. Upon receiving the IGMP
leave group packets on a dynamic member port, the switch forwards those
packets to the router ports.
8.1.5 Understanding IGMP Profiles
IGMP Profiles is the group filterings actually, defines a series of multicast address
range and the access to those multicast addresses(permit/deny), including
“Multicast address range in the SVGL mode”, “Filtering multicast data range of
router port”, “IGMP Filtering range”.
8.1.6 Understanding Working Modes of IGMP Snooping
DISABLE: The IGMP Snooping does not work in this mode. That is, the switch
does not snoop the IGMP messages between the host and the router. Multicast
frames are forwarded in the VLAN in the broadcast form.
IVGL(Independent VLAN Group Learning): In this mode, the multicast flows in
different VLANs are independent. A host can only request multicast flows to the
router interface in the same VLAN. Upon receiving the multicast flow in any VLAN,
the switch forwards the flow to the member port in the same VLAN.
SVGL(Shared VLAN Group Learning): In this mode, the hosts in different
VLANs share the same multicast flow. A host can request multicst flows across
VLANs. By designating a Shared VLAN, you can only forward the multicast flows
received in this Shared VLAN to other member ports in different VLANs. In the
SVGL mode, IGMP Profile must be used to divide the multicast address range,
within which the multicast flow can be forwarded across VLANs. By default, all
group range is not within the SVGL range and all multicast flows are dropped. As
shown in Figure-3:
Figure-3 Multicast Flow in the Shared VLAN forwarding across VLANs
Promiscuous mode: also known as IVGL-SVGL mode. In this mode, the IVGL
mode and the SVGL mode can co-exist. Use IGMP Profile to divide a set of
multicast address range to the SVGL, within which the member port of the
multicast forwarding entry can be forwarded across VLANs and without which the
member ports are forwarded in the same VLAN.