3Com Switch 7750 Configuration Guide

170 CHAPTER 21: SHARED VLAN CONFIGURATION
Working Principle of
Shared VLAN
After shared VLAN is configured, all the MAC address entries learned by ports will
be maintained on the MAC address forwarding table of the shared VLAN, which
can be used to forward all the VLAN packets in the device.
With shared VLAN configured, the forwarding information about packets with the
destination MAC address MAC-A learned by the customer port will be saved in
the MAC address forwarding table of the shared VLAN. The packets received on
the ports connected to the service provider can retrieve their forwarding path
directly through looking up in the MAC address forwarding table of the shared
VLAN. In this way, fewer unknown unicast packets will be broadcast by the device.
As a result, the network resources are saved and the efficiency of the device is
improved.
Shared VLAN
Configuration
Configuring Shared
VLAN on Fabric
n
For a Switch 7708R with two Fabrics equipped, the shared VLAN configured on
the primary Fabric also takes effect on the secondary Fabric.
Configuring Shared
VLAN on I/O Module
n
With shared VLAN enabled, the packets of the current I/O Module or Fabric are
forwarded according to the MAC address table of the shared VLAN. So you need
to add the ports of all the packets to be forwarded to the shared VLAN. The
operation of adding ports to the shared VLAN is the same as the operation of
adding ports to a common VLAN. Refer to “Configuring a Port-Based VLAN” on
page 97 for details.
c
CAUTION: The shared VLAN can destroy RRPP rings and disable the RRPP feature,
and thus cause rings in the network. So make sure that the RRPP feature and the
shared VLAN feature is not enabled on a switch at the same time.
Displaying Shared
VLAN
After the above-mentioned configuration, you can execute the display command
in any view to view the running information about the shared VLAN, so as to verify
the configuration.
Table 102 Configure shared VLAN on Fabric
Operation Command Description
Enter system view system-view -
Configure shared VLAN on
Fabric
shared-vlan vlan-id
mainboard
Required
By default, no shared VLAN is
configured on the Fabric.
Table 103 Configure shared VLAN on I/O Module
Operation Command Description
Enter system view system-view -
Configure shared VLAN on I/O
Module
shared-vlan vlan-id
slot slot-number
Required
By default, no shared VLAN is
configured on the I/O Module.