Alcatel Carrier Internetworking Solutions Omni Switch/Router - Manual (Page 696)

Page 23-2
How Devices are Assigned to Multicast VLANs
If the recipients of the multicast traffic were defined using the port rule, each specified port is
then marked as a member of the multicast
VLAN .
If the recipients of the multicast traffic were defined using the MAC address rule to specify the
MAC addresses of the receiving devices, no action is taken until a frame is received from one
of those devices. When such a frame is received, the switch learns the device, adds its MAC
address to the filtering database, and marks the port on which the frame was received as a
member of the multicast
VLAN . Note that the MAC address does not itself become a member
of the multicast VLAN , even though it is a recipient of the multicast traffic. Only ports are
members of multicast VLAN s.
When the switch receive multicast traffic that has an address specified as a multicast address
for the multicast
VLAN , the traffic is switched to the ports defined as VLAN members.
♦ Please Take Note ♦
The source port of the multicast traffic (i.e., the port
through which multicast traffic enters the switch) can
be a member of any Group. The source port does not
need to be a member of the same Group as recipient
ports. Note that the source port does not become a
member of the multicast
VLAN .
Although some leakage may occur before devices are assigned to AutoTracker VLAN s, no
leakage occurs in conjunction with device assignment to multicast VLAN s.
♦ Please Take Note ♦
There is no default multicast VLAN . Unless you
explicitly create multicast VLANs , none will exist.
Multicast VLANs and Multicast Claiming
The goal of multicast claiming and multicast VLAN s is the same—to free the MPX module from
processing multicast traffic. Both methods off-load multicast traffic processing to the switch-
ing modules. However, multicast
VLAN s can be seen as a refinement to multicast claiming.
Multicast claiming claims the MAC addresses of all source devices sending multicast traffic and
places those MAC addresses in the CAM s of all switching modules in a switch. Instead of
claiming all multicast traffic, multicast VLAN s claim only the traffic from the multicast address
you specify. In addition, this multicast address is only placed in the CAM s of switching
modules with destination ports that are part of the multicast VLAN .