Monitor: Spanning Tree
Overview
This section provides information for Spanning Tree in Monitor.
The Switch supports Spanning Tree Protocol (STP), Common and Internal Spanning Tree (CIST), and Multiple Spanning Tree (MST).
Spanning Tree
Use this screen to view Switch spanning tree settings.
CIST Settings
Use this screen to view the Switch’s spanning tree CIST instance. Click Monitor > Spanning Tree > CIST.
Each field is described in the following table.
Label | Description |
|---|---|
CIST Instance | |
State | This field displays the state. |
Bridge Identifier | This is the unique identifier for this bridge, consisting of the bridge priority plus the MAC address. |
Designated Root Bridge | Root bridge refers to the base of the spanning tree. |
External Root Path Cost | The cost of the path from this bridge to the CIST Root Bridge. |
Regional Root Bridge | Root bridge refers to the base of the spanning tree. |
Internal Root Path Cost | The cost of the path from this bridge to the internal Regional Root Bridge. |
Designated Bridge | For each LAN segment, a designated bridge is selected. This bridge has the lowest cost to the root among the bridges connected to the LAN. |
Root Port | On each bridge, the bridge communicates with the root through the root port. The root port is the port on this Switch with the lowest path cost to the root (the root path cost). If there is no root port, then this Switch has been accepted as the root bridge of the spanning tree network. |
Remaining Hops | This field displays the number of remaining hops. |
Last Topology Change | Topology change information is directly propagated throughout the network from the device that generates the topology change. |
CIST Port
Use this screen to view the Switch’s spanning tree CIST port status. Click Monitor > Spanning Tree > CIST Port.
Each field is described in the following table.
Label | Description |
|---|---|
Port | This field displays the port number. |
Identifier (Priority / Port Id) | This field displays the identifier (in priority / port number). |
External Path Cost Operation | Path cost is the cost of transmitting a frame on to a LAN through that port. It is recommended to assign this value according to the speed of the bridge. The slower the media, the higher the cost |
Internal Path Cost Operation | Path cost is the cost of transmitting a frame on to a LAN through that port. It is recommended to assign this value according to the speed of the bridge. The slower the media, the higher the cost |
Designated Root Bridge | Root bridge refers to the base of the spanning tree. |
External Root Cost | This field displays the external root cost. |
Regional Root Bridge | Root bridge refers to the base of the spanning tree. |
Internal Root Cost | This field displays the internal root cost. |
Designated Bridge | For each LAN segment, a designated bridge is selected. This bridge has the lowest cost to the root among the bridges connected to the LAN. |
Edge Port Operation | An edge port changes its initial STP port state from blocking state to forwarding state immediately without going through listening and learning states right after the port is configured as an edge port or when its link status changes. |
P2P MAC Operation | This field displays the state of the P2P MAC operation. |
Port Role | This field displays the state of the port role. |
Port State | This field displays the state of the port. |
MST Settings
Use this screen to view the Switch’s spanning tree MST instance. Click Monitor > Spanning Tree > MST.
Each field is described in the following table.
Label | Description |
|---|---|
MST Instance | |
MST ID | This is the unique identifier for this MST. Select a number from the drop-down menu to display results. |
State | This field displays the state. |
Regional Root Bridge | Root bridge refers to the base of the spanning tree. |
Internal Root Cost | This field displays the internal root cost. |
Designated Bridge | For each LAN segment, a designated bridge is selected. This bridge has the lowest cost to the root among the bridges connected to the LAN. |
Root Port | On each bridge, the bridge communicates with the root through the root port. The root port is the port on this Switch with the lowest path cost to the root (the root path cost). If there is no root port, then this Switch has been accepted as the root bridge of the spanning tree network. |
Remaining Hops | This field displays the number of remaining hops. |
Last Topology Change | Topology change information is directly propagated throughout the network from the device that generates the topology change. |
MST Port
Use this screen to view the Switch’s spanning tree MST port status. Click Monitor > Spanning Tree > MST Port.
Each field is described in the following table.
Label | Description |
|---|---|
MST Port | |
MST ID | This is the unique identifier for this MST. Select a number from the drop-down menu to display results. |
Port | This field displays the port number. |
MSTI ID | A VLAN can be mapped to a specific Multiple Spanning Tree Instance (MSTI). MSTI allows multiple VLANs to use the same spanning tree. |
Identifier (Priority / Port Id) | This field displays the identifier (in priority / port number). |
Internal Path Cost(Operation) | Path cost is the cost of transmitting a frame on to a LAN through that port. It is recommended to assign this value according to the speed of the bridge. The slower the media, the higher the cost. |
Regional Root Bridge | Root bridge refers to the base of the spanning tree. |
Internal Root Cost | This field displays the internal root cost. |
Designated Bridge | For each LAN segment, a designated bridge is selected. This bridge has the lowest cost to the root among the bridges connected to the LAN. |
Port Role | This field displays the state of the port role. |
Port State | This field displays the state of the port. |
STP Statistics
(R)STP detects and breaks network loops and provides backup links between switches, bridges or routers. It allows a Switch to interact with other (R)STP-compliant switches in your network to ensure that only one path exists between any two stations on the network.
The Switch uses IEEE 802.1w RSTP (Rapid Spanning Tree Protocol) that allows faster convergence of the spanning tree than STP (while also being backwards compatible with STP-only aware bridges). In RSTP, topology change information is directly propagated throughout the network from the device that generates the topology change. In STP, a longer delay is required as the device that causes a topology change first notifies the root bridge and then the root bridge notifies the network. Both RSTP and STP flush unwanted learned addresses from the filtering database. In RSTP, the port states are Discarding, Learning, and Forwarding.
In this user’s guide, “STP” refers to both STP and RSTP.Use this screen to view the Switch’s spanning tree STP statistics. Click Monitor > Spanning Tree > STP Statistics.
Each field is described in the following table.
Label | Description |
|---|---|
MST Port | |
Port | This field displays the port number. |
Configuration BDPUs Received | This field displays the configuration BDPUs received. |
TCN BDPUs Received | This field displays the TCN BDPUs received. |
MSTP BDPUs Received | This field displays the Multiple Spanning Tree Protocol (MSTP) BDPUs received. |
Configuration BDPUs Transmitted | This field displays the configuration BDPUs transmitted. |
TCN BDPUs Transmitted | This field displays the TCN BDPUs transmitted. |
MSTP BDPUs Transmitted | This field displays the Multiple Spanning Tree Protocol (MSTP) BDPUs transmitted. |