Alcatel Carrier Internetworking Solutions Switch/Router ユーザーズマニュアル

Page 23-1

Multicast 

VLANs

 enable you to control the flooding of multicast traffic in your network. For 

example, you can define a multicast 

VLAN

 for all users that want to receive 

CNN

 Newscasts or 

any other video feed or combination of feeds. 

You define the multicast traffic to be transmitted by specifying a multicast address. You define 
the recipients of the multicast traffic by specifying ports and/or specific 

MAC

 addresses. The 

members of a multicast 

VLAN

 consist of the ports specified to 

 the multicast traffic and 

the ports to which 

MAC

 address recipients are connected. Instructions for creating multicast 

VLANs

Note the difference between multicast 

VLAN

s and AutoTracker 

VLAN

s. In AutoTracker 

VLAN

s, 

devices are assigned to 

VLAN

s by examination of the frames that 

 from those devices. 

The members of an AutoTracker 

VLAN

 consist of source devices that fit the 

VLAN

’s policies 

and the ports to which those source devices are connected.

There are several differences between the configuration of multicast 

VLAN

s and the configura-

tion of AutoTracker 

VLAN

s. The following is a summary of points to note when configuring 

multicast 

VLAN

s:

• You can not configure routing for multicast 

VLAN

s. Multicast 

VLAN

s are independent broad-

cast domains for multicast traffic originating from a multicast address and transmitted to 
one or more recipients.

• Multicast 

VLAN

s allow three rules: Port, 

MAC

 Address, and multicast policy.

• There is not a default multicast 

VLAN

. Therefore, you can define rules for all 32 available 

multicast 

VLAN

s. All ports (even those that eventually become part of a multicast 

VLAN

) 

start off in the standard AutoTracker default 

VLAN

 #1, but they only get assigned to a multi-

cast 

VLAN

 if you explicitly assign them to one.

• All multicast 

VLAN

s include the multicast policy. This policy specifies the multicast address. 

You use the other two rules—Port and 

MAC

 Address—to define the destination of the 

multicast traffic.