3Com 3CRWX120695A Reference Manual page 205

3 To add a multicast router port, select the Multicast Router Present
checkbox for each port you want to add.
By default, ports are not selected. To remove a static multicast receiver
port, clear the checkbox.
4 To close the wizard and save the changes, click Finish.
Configuring STP Fast Convergence Features
The standard STP timers delay traffic forwarding briefly after a topology
change. The time a port takes to change from the listening state to the
learning state or from the learning state to the forwarding state is called
the forwarding delay. In some configurations, this delay is unnecessary.
The WX switch provides the following fast convergence features to
bypass the forwarding delay:
Backbone fast convergence
Uplink fast convergence
Backbone Fast Convergence Backbone fast convergence accelerates
a port's recovery following the failure of an indirect link. Normally, when a
forwarding link fails, a bridge that is not directly connected to the link
does not detect the link change until the maximum age timer expires.
Backbone fast convergence enables the WX switch to listen for bridge
protocol data units (BPDUs) sent by a designated bridge when the
designated bridge's link to the root bridge fails, and immediately verifies
whether BPDU information stored on a port is still valid. If the BPDU
information on the port is no longer valid, the bridge immediately starts
the listening stage on the port.
If you plan to use the backbone fast convergence feature, you must
enable it on all the bridges in the spanning tree.
CAUTION: The backbone fast convergence feature is not compatible
with switches that are running standard IEEE 802.1D Spanning Tree
implementations. This includes switches running Rapid Spanning Tree or
Multiple Spanning Tree.
Uplink Fast Convergence Uplink fast convergence enables a WX
switch that has redundant links to the network core to immediately
change the state of a backup link to forwarding if the primary link to the
root fails. Uplink fast convergence bypasses the listening and learning
states to immediately enter the forwarding state.
Configuring VLANs 205