Nortel Networks 2300 manual Configuring and Managing STP Fast Convergence Features

Configuring and Managing Spanning Tree Protocol 319

To change the maximum acceptable age for root bridge hello packets on all VLANs to 15 seconds, type the following command:

23x0# set spantree maxage 15 all

success: change accepted.

Configuring and Managing 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 WSS 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 WSS 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 verifies 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.

Nortel WLAN Security Switch 2300 Series Configuration Guide