Introduction To Multicast Vlan; Configuring Multicast Vlan - 3Com Switch 4800G 24-Port Configuration Manual

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Introduction to
Multicast VLAN
Configuring Multicast
VLAN
M
ULTICAST
As shown in Figure 180, in the traditional multicast programs-on-demand mode,
when hosts that belong to different VLANs, Host A, Host B and Host C require
multicast programs on demand service, Router A needs to forward a separate
copy of the multicast data in each VLAN. This results in not only waste of network
bandwidth but also extra burden on the Layer 3 device.
Figure 180 Before and after multicast VLAN is enabled on the Layer 2 device
Multicast packet transmission
without Multicast VLAN
Source
Switch A
Host A
Receiver
VLAN 10
Host B
Receiver
VLAN 20
Multicast packets
To solve this problem, you can enable the multicast VLAN feature on Switch A,
namely configure the VLANs to which these hosts belong as sub-VLANs of a
multicast VLAN on the Layer 2 device and enable Layer 2 multicast in the multicast
VLAN. After this configuration, Router A replicates the multicast data only within
the multicast VLAN instead of forwarding a separate copy of the multicast data to
each VLAN. This saves the network bandwidth and lessens the burden of the Layer
3 device.
Follow these steps to configure a multicast VLAN:
To do...
Enter system view
VLAN C
ONFIGURATION
Router A
Source
Host C Host A
Receiver Receiver
VLAN 30 VLAN 10
Use the command...
system-view
Multicast packet transmission
when Multicast VLAN runs
Router A
Switch A
Receiver
Host B
Receiver
VLAN 20
Remarks
-
Host C
VLAN 30