User`s manual

216
DWS-1008 User’s Manual
D-Link Systems, Inc.
Conguring and Managing STP
216D-Link Systems, Inc.
Changing the STP Maximum Age
To change the maximum age, use the following command:
set spantree maxage aging-time {all | vlan vlan-id}
Specify an age from 6 through 40 seconds. The default is 20 seconds.
The all option applies the change to all VLANs. Alternatively, specify an individual VLAN. To
change the maximum acceptable age for root bridge hello packets on all VLANs to 15 seconds,
type the following command:
DWS-1008# set spantree maxage 15 all
success: change accepted.
Conguring and Managing STP Fast Convergence Features
The standard STP timers delay trafc forwarding briey 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 congurations, this delay is
unnecessary. The switch provides the following fast convergence features to bypass the
forwarding delay:
• Port fast
• Backbone fast
• Uplink fast
Port Fast Convergence
Port fast convergence bypasses both the listening and learning stages and immediately
places a port in the forwarding state. You can use port fast convergence on ports that are
directly connected to servers, hosts, or other MAC stations.
Note: Do not use port fast convergence on ports connected to other bridges.
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 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. The switch
immediately veries whether BPDU information stored on a port is still valid. If not, the bridge
immediately starts the listening stage on the port.
Note: If you plan to use the backbone fast convergence feature, you must enable it on all the
bridges in the spanning tree.