User Manual
UMN:CLI
V8102
487
10.2
Multicast Functions
The V8102 provides various multicast functions including Layer 2 multicast forwarding,
which allow you to achieve the fully effective and flexible multicast deployment.
10.2.1
Multicast Forwarding Database
Internally, the V8102 forwards the multicast traffic referred to the multicast forwarding da-
tabase (McFDB). The McFDB maintains multicast forwarding entries collected from mul-
ticast protocols and features, such as PIM, IGMP, etc.
The McFDB has the same behavior as the Layer 2 FDB. When certain multicast traffic
comes to a port, the switch looks for the forwarding information (the forwarding entry) for
the traffic in the McFDB. If the McFDB has the information for the traffic, the switch for-
wards it to the proper ports. If the McFDB does not have the information for the traffic, the
switch learns the information on the McFDB, and then floods it to all ports. If the infor-
mation is not referred to forward another multicast traffic during the given aging time, it is
aged out from the McFDB.
10.2.1.1
Blocking Unknown Multicast Traffic
When certain multicast traffic comes to a port and the McFDB has no forwarding infor-
mation for the traffic, the multicast traffic is flooded to all ports by default. You can config-
ure the switch not to flood unknown multicast traffic.
To configure the switch to discard unknown multicast traffic, use the following command.
Command
Mode
Description
ip unknown-multicast
[
port
PORTS
]
block
Global
Configures the switch to discard unknown multicast
traffic.
PORTS
: port number (1/1, 1/2, 2/1, …)
no ip unknown-multicast
[
port
PORTS
]
block
Configures the switch to flood unknown multicast traf-
fic. (default)
This command should not be used for the ports to which a multicast router is attached!
10.2.1.2
Forwarding Entry Aging
To specify the aging time for forwarding entries on the McFDB, use the following com-
mand.
Command
Mode
Description
ip mcfdb aging-time
<10-10000000>
Global
Specifies the aging time for forwarding entries on the
McFDB.
10-10000000: aging time (default: 300 seconds)
no ip mcfdb aging-time
Deletes the specified aging time for forwarding entries.
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