Assume that all the response packets of the server belong VLAN 10. Since the
switch learns PC1’s MAC address with VID 2, it will broadcast the response
packets whose VID is 10 upon their arrival. Consequently, PC2 will receive the
packets that the server sends to PC1, which are unuseful. This wastes
bandwidth and PC2’s resource. How to avoid this problem? Administrator can
set VLAN 10 to be a Share VLAN, so that the switch will replicate the MAC
address to VLAN 10 when it learns the MAC address with VID 2.
Table 2
In this way, when the response packets from the server arrive the switch, the
switch can find the address with VID 10 and send them out only through port 1.
A switch supports only one Share VLAN.
Only replicating dynamic MAC address and static MAC address is allowed.
The protocol VLAN, private VLAN, remote VLAN or interface address table
replication function is mutually exclusive with the Share VLAN, and
vice versa.
The super VLAN cannot be set to be the Share VLAN, and vice versa.
The sub VLAN cannot be set to be the Share VLAN, and vice versa.
The MAC addresses in the Share VLAN will not be replicated to the super
VLAN, and vice versa.
Once a sub-address is deleted, it will be replicated only after its home
address is aged out or deleted and the sub address is learned again.
The MAC address replication will fail in case of shortage of the MAC
address table. Once replication failed, the home address and
replicated sub-address will be deleted if the home address is a
dynamic address or the replicated sub-address will be deleted if the
home address is a static address.
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