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Any configuration changes made locally on the switch won't be synchronized with Sophos Central. We recommend making changes from the Sophos Central control panel instead.

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https://docs.sophos.com/nsg/switch/help/en-us/index.html?contextId=user-guide-features-configure-STP-global-settings

Global settings

Use Global settings to turn STP on or off and to view Root bridge information.

You can configure the following global settings:

Option Description
STP state Select Turned on or Turned off to turn on or off spanning tree on Sophos Switch.
BPDU forwarding Select Turned on or Turned off to turn on or off BPDU forwarding on Sophos Switch.
Forced version Select the version of STP to use from the drop-down menu. The available options are MSTP or RSTP.
Configuration name Set the configuration name of the STP setting. The maximum number of characters is 32.
Configuration revision Set the MSTP revision level. The range of the level is from 0 to 65535. The default is 0.
Priority Set the priority to define the root bridge of the switch. The Priority number must be a multiple of 4096.
Forward delay Set the maximum time required for a frame to be transmitted through all bridges. The default is 15 seconds.
Maximum age The maximum age timer controls the maximum length of time before saving the configuration BPDU information of a bridge port. By default, this time is 20 seconds, but you can set the time between 6 and 40 seconds.
Tx hold count

Tx hold count controls the number of BPDUs sent before pausing for one second.

Default: 6 seconds

Range: 1-10 seconds.
Hello time Hello time is the interval for BPDUs being sent on a port. The default is 2 seconds, and can be changed between 1 and 2 seconds.

Click Apply to save the settings or Reset to clear the settings.

Root bridge information

The Root Bridge is an administrative point for all spanning tree calculations to determine which links to block to prevent network loops. From here, you can view all the information regarding the Root Bridge within the STP.

All other decisions regarding a root bridge are made in a spanning-tree network, such as ports being blocked and ports being put in a forwarding mode. The root bridge is the "root" of the "tree" within a spanning-tree network. The root bridge has the lowest bridge ID in the spanning-tree network. STP devices exchange Bridge Protocol Data Units (BPDUs) periodically. All bridges listen for Hello BPDUs transmitted from the root bridge. If a bridge does not get a BPDU after a predefined interval (Maximum Age), the bridge treats the link to the root bridge as being down. The bridge then negotiates with other bridges to reconfigure the network to reestablish a valid network topology.

Option Description
Bridge Address Shows the MAC address of the bridged network.
Root Address Displays the root bridge MAC address. Root in root bridge refers to the base of the spanning tree.
Priority Shows the priority for the bridge. Switches running STP are each given a priority. Once BPDUs are exchanged, the switch with the lowest priority value becomes the root bridge.
Forward Delay Shows the Switch Forward Delay Time. This is the time (in seconds) the root switch will wait before changing states (called listening to learning).
Maximum Age This is the time a bridge waits before sending a configuration message. The default is 20 seconds.
Hello Time Shows the switch Hello time. This is how long a bridge stays in a listening and learning state before packets are forwarded. The default is 2 seconds.