311Nortel WLAN Security Switch 2300 Series Configuration GuideConfiguring and ManagingSpanning Tree ProtocolThe purpose of the Spanning Tree Protocol (STP) is to maintain a loop-free network. A loop-free path is accomplishedwhen a device recognizes a loop in the topology and blocks one or more redundant paths.Mobility System Software (WSS Software) supports 802.1D and Per-VLAN Spanning Tree protocol (PVST+).• WSS Software uses 802.1D bridge protocol data units (BPDUs) on VLAN ports that are untagged. However, eachVLAN still runs its own instance of STP, even if two or more VLANs contain untagged ports. To run a singleinstance of STP in 802.1D mode on the entire switch, configure all network ports as untagged members of the sameVLAN.• WSS Software uses PVST+ BPDUs on VLAN ports that are tagged. PVST+ BPDUs include tag information in the802.1Q field of the BPDUs. WSS Software runs a separate instance of PVST+ on each tagged VLAN.Enabling the Spanning Tree Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312Changing Standard Spanning Tree Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313Configuring and Managing STP Fast Convergence Features . . . . . . . . . . . . . . . . . . 319Displaying Spanning Tree Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326Spanning Tree Configuration Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332Note. STP does not run on AP access ports or wired authentication ports and does notaffect traffic flow on these port types.Note. When you create a VLAN, STP is disabled on the new VLAN by default,regardless of the STP state of other VLANs on the device.Note. The IEEE 802.1D spanning tree specifications refer to networking devices thatforward Layer 2 traffic as bridges. In this context, an WSS switch is a bridge. Where thismanual or the product interface uses the term bridge, you can assume the term isapplicable to the WSS switch.
