Configuring Multicast Vlans; Overview - HP FlexFabric 5700 Series Configuration Manual

Configuring multicast VLANs

Overview

As shown in
When Switch A (Layer 3 device) receives multicast data for that group, it sends three copies of the
multicast data to Switch B (Layer 2 device). This occupies a large amount of bandwidth and increases the
burden on the Layer 3 device.
Figure 18 Multicast transmission without the multicast VLAN feature
Source
After a multicast VLAN is configured on Switch B, Switch A sends only one copy of the multicast data to
the multicast VLAN on Switch B. This method saves network bandwidth and lessens the burden on the
Layer 3 device.
Multicast VLANs include sub-VLAN-based multicast VLANs and port-based multicast VLANs.
Sub-VLAN-based multicast VLAN
As shown in
Host A, Host B, and Host C are in VLAN 2 through VLAN 4, respectively.
•
On Switch B, VLAN 10 is a multicast VLAN. VLAN 2 through VLAN 4 are sub-VLANs of VLAN 10.
•
• IGMP snooping is enabled for the multicast VLAN and its sub-VLANs.
Figure 18, Host A, Host B, and Host C are in different VLANs and the same multicast group.
Multicast packets
VLAN 2
VLAN 3
VLAN 4
Switch A
IGMP querier
Figure 19:
VLAN 2
VLAN 3
Switch B
VLAN 4
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Receiver
Host A
Receiver
Host B
Receiver
Host C