Alcatel Omni Switch/Router, Руководство пользователя

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Page 23-3
Frame Flooding in Multicast
VLAN
s
Multicast traffic is flooded as follows in an environment that includes multicast
VLAN
s:
• If the destination address is a multicast address,
and
• if the destination multicast address is in the filtering database,
and
• if the destination multicast address is a specified multicast address for a multicast
VLAN
,
then
flood the traffic on all ports that have at least one multicast
VLAN
in common with the desti-
nation multicast address. This is illustrated below. If any of the conditions described above
are untrue, the traffic is flooded as it is for normal AutoTracker
VLANs
.
12345678
123456
Omni Switch/Router
Port 2
Client A
Client B
Client C
Client D
Server 1
Server 2
Group 3
Ports 1 – 6
Multicast
VLAN
10
Ports 3 and 4
Multicast address = CNN
Port 1
Port 3
Port 4 4
Multicast
VLAN
20
Ports 5 and 6
Multicast address = NBC
CNN
Port 6
Port 5 rt 5
CNN
NBC
NBC
Multicast
Address CNN
Multicast
Address NBC
When the Switch receives a frame with multicast destination address
CNN
from Server 1, the Switch locates the
CNN
multicast address in
the filtering database (or places the address into the filtering data-
base if it is not there already). The Switch then uses this address to
determine the multicast
VLAN
(s) – if any – out which to flood the
frame. In this example, the Switch determines that multicast
VLAN
10
should receive the frame, since multicast
VLAN
10 spec-
ifies multicast address
CNN
. The Switch
then checks through the port
records to determine if any ports
are assigned to multicast
VLAN
10. It finds ports 3 and 4 are so
assigned, and floods the frame
out those ports only.
For this Example, the Filtering Database is:
MAC
Address Port
VLAN
Membership Type
CNN
n/a 10
MVLAN
NBC
n/a 20
MVLAN
Server 1 1 1
BRIDGE
Server 2 2 1
BRIDGE
Client A 3 1
BRIDGE
Client B 4 1
BRIDGE
Client C 5 1
BRIDGE
Client D 6 1
BRIDGE
For this Example, the Port Records are:
Port
VLAN
Membership
MVLAN
Membership
1 1 none
2 1 none
3 1 10
4 1 10
5 1 20
6 1 20
The filtering database is a record of source
MAC
addresses, their ports of entry into the switch, and
their
VLAN
membership. Note that the ports of entry
for multicast addresses
CNN
and
NBC
are irrelevant
in the filtering database. This table is for informa-
tional purposes—it is not available in the UI.
The port records show the
VLAN
and multicast
VLAN
(MVLAN) membership of each port. This
table is for informational purposes only—it is
not available as a UI command.