Dell POWEREDGE M1000E - Manual (Page 601)

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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-13270-03
Chapter 24 Configuring IGMP Snooping and MVR
Understanding Multicast VLAN Registration
switch to join the appropriate multicast. If the IGMP report matches one of the configured IP multicast
group addresses, the switch CPU modifies the hardware address table to include this receiver port and
VLAN as a forwarding destination of the specified multicast stream when it is received from the
multicast VLAN. Uplink ports that send and receive multicast data to and from the multicast VLAN are
called MVR source ports.
Figure 24-3 Multicast VLAN Registration Example
When the subscriber changes channels or stops the multicast stream, the server sends an IGMP leave
message for the multicast stream. The switch CPU sends a MAC-based general query through the
receiver port VLAN. If there is another device in the VLAN still subscribing to this group, that device
must respond within the maximum response time specified in the query. If the CPU does not receive a
response, it eliminates the receiver ports as a forwarding destination for this group.
Without Immediate Leave, when the switch receives an IGMP leave message from a subscriber on a
receiver port, it sends out an IGMP query on that port and waits for IGMP group membership reports. If
no reports are received in a configured time period, the receiver port is removed from multicast group
membership. With Immediate Leave, an IGMP query is not sent from the receiver port on which the
IGMP leave was received. As soon as the leave message is received, the receiver port is removed from
multicast group membership, which speeds up leave latency. Enable the Immediate-Leave feature only
on receiver ports to which a single receiver device is connected.
MVR eliminates the need to duplicate multicast traffic for subscribers in each VLAN. Multicast traffic
for all channels is only sent around the VLAN trunk once—only on the multicast VLAN. The IGMP
leave and join messages are in the VLAN to which the subscriber port is assigned. These messages
Multicast VLAN
SP
SP
SP
SP
RP1 RP2 RP3 RP4 RP5
RP = Receiver Port
SP = Source Port Note: All source ports belong to
the
multicast VLAN.
SP
Cisco router
Multicast
server
Server
Switch
Blade Switch
Switch Switch
201915
Server Server Server Server