SWM281 Spanning Tree

The information in this page is updated in accordance with firmware version SWM2_R_00.01.06.3.

Summary

The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. STP's primary function is to prevent loops in Ethernet networks. Ethernet loops can occur when there are redundant paths between network switches, and if not managed properly, they can lead to broadcast storms and network congestion. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails.

Ports

The Ports page displays the status of ports and allows to enable `Edge` port option.

Field	Value	Description
Port name		Name of the port.
Protocol	STP | RSTP | Inactive	Protocol used by the port. Possible protocols: STP: Spanning tree protocol. RSTP: Rapid spanning tree protocol. Inactive: Neither protocol is used.
State	Learning | Forwarding | Inactive | Blocking | Listening | Discarding	State of the port.Possible states: Learning: Does not yet forward frames. Tries to fill MAC table. Forwarding: Normal operation receiving and forwarding frames. Inactive: STP only. Port is disconnected or disabled. Blocking: STP only. Would cause a switching loop if it was active. Listening: STP only. Does not forward frames. Awaits information if it has to be in blocking state. Discarding: RSTP only. Does not forward frames.
Role	Root | Designated | Alternate | Backup | Inactive	Role of the port. Roles are used only for RSTP. Possible roles: Root: A forwarding port that is the best port leading to root bridge. Designated: A forwarding port that is connecting other bridges to root. Alternate: An alternate port leading to the root bridge. Backup: A backup/redundant port connects to a segment where another bridge port already connects. Inactive: Port is disconnected or disabled.
Port cost		Cost of the port is determined by the port speed. Higher speed ports have lower cost. Lower cost is more preferred by spanning tree.
Port priority		Priority of the port is used when costs of the ports are the same. Lower priority is more preferred by spanning tree. Also the lowest priority port is put into forwarding state.
Edge port	off | on; default: off	When enabled a port enters the forwarding state immediately, bypassing the listening and learning states. This option is intended only for ports that connect to end devices.

General

Field	Value	Description
Mode	Disabled | STP | RSTP; default: RSTP	STP - provides a single path between any two end stations, avoiding and eliminating loops. RSTP - detects network topologies to provide faster convergence of the spanning tree. Disabled - turns off spanning tree protocol.
Priority	Integer [0..61440]; default: 32768	STP priority. The lower the number, the higher the priority.
Max age	Integer [6..40]; default: 20	Maximum expected arrival time of hello bridge protocol data units (BPDUs).
Forward delay	Integer [4..30]; default: 15	How long an STP bridge port remains in the listening and learning states before transitioning to the forwarding state.
Hello time	Integer [1..10]; default: 2	Number of seconds between transmissions of configuration BPDUs.
Hold count	Integer [1..10]; default: 6	The number or BPDUs that can be transmitted during every hello time period ranges from a minimum of one and a maximum of not more than defined value.
Max hops	Integer [6..40]; default: 20	Maximum number of bridge hops allowed in the network.