• Wireless Network Manager
• Getting Started with Wireless Network Manager
  • About Wireless Network Manager
  • Using the Wireless Network Manager Interface
  • Using Wireless Network Manager Guide
• Overview
  • Dashboard
  • Alerts
  • Threats
  • Logs
  • Audit
• Using Air Marshal
  • RF Survey
    • Discovered Aps
    • Discover and Report Unassociated Wireless Clients
  • RF Spectrum
  • RF Monitor
  • Packet Capture
    • Wireless
    • Ethernet
  • Bluetooth LE
• Managing Your Network
  • Network Hierarchy
  • Network Topology
  • Zones
  • Devices
    • Managing Access Points
      • Managing the Configuration of Access Points
        • General
          • Bridge Mode
          • NAT Mode
        • Radio
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          • Activating SSL VPN
          • Editing SSL-VPN
      • Upgrading the Firmware for Specific Access Points
      • SonicWave Diagnostics
        • Testing Connectivity With Your Gateway or DNS Addresses
        • Testing Connectivity With Ping, Traceroute, or NSLookup
    • Viewing the Wireless Client Journey
    • Port Settings
    • Managing Switches
    • Managing Switch Clients
• Managing Policies
  • Policy Hierarchy
    • Select an AP Policy
      • General
      • System
      • Radio
      • Mesh Network
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      • • Certificate
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      • RRM (Radio Resource Management)
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      • General
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        • Spanning Tree Protocol
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        • Dynamic Host Configuration Protocol (DHCP) Relay
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          • Sign-on with One-Time Passwords
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        • Customized Splash Page
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          • Collect User Feedback from a Customized Splash Page
    • Select a Security Policy
      • CFS (Content Filtering Service)
        • General
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        • General
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        • Customize Block Page
      • CAV (Cloud Gateway Anti-Virus)
        • General
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        • Customize Block Page
      • ACL
        • General
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      • Geo-IP & Botnet
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  • AP Policies
  • Using Tags to Manage Access Points and SSIDs
    • Using Tags to Manage Access Points
      • Adding Tags to an Access Point
      • Removing Tags Associated with an Access Point
      • Viewing Tags Associated with an Access Point
    • Using Tags to Manage SSIDs
      • Adding Tags to an SSID Group
      • Removing Tags from an SSID Group
      • Viewing Tags Associated with an SSID Group
  • QoS Policies
  • Wi-Fi Multimeda (WMM) Profiles
    • Creating Wi-Fi Multimeda (WMM) Policies
    • Enabling Wi-Fi Multimeda (WMM) Policies
  • Managing Switch Policies
    • Adding Switch Policies
    • Editing Switch Policies
  • Managing Switch Port Policies
    • Adding Switch Port Policies
      • General
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    • Capture Advanced Threat Protection
      • Creating Capture Advanced Threat Protection Security Policies
      • Adding an MD5 Hash to the Exclusion List
    • Cloud Anti-Virus
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      • Creating and Editing Access Control Policies
    • Geo-IP & Botnet
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  • Managing SNMP Policies
    • Setting the SNMP ID
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• Objects
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• Admin
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  • Certificates
    • Batch Import
    • Import Certificates
  • Using the WiFi Planner
• SonicWall Support
  • About This Document

Spanning Tree Protocol

The Spanning Tree Protocol (STP) can be used to detect and disable network loops, and to provide backup links between Switches. This allows the Switch to interact with other bridging devices in your network to ensure that only one route exists between any two stations on the network, and provide backup links which automatically take over when a primary link goes down.

STP provides a tree topology for the Switch. There are different types of Spanning tree versions, supported, including Spanning Tree Protocol (STP) IEEE802.1D, Multiple Spanning Tree Protocol (MSTP) IEEE802.1w, and Rapid Spanning Tree Protocol (RSTP) IEEE802.1s. Please note that only one spanning tree can be active on the Switch at a time.

Spanning Tree Protocol (STP) is a Layer 2 protocol that runs on Switches. Spanning Tree Protocol (STP) allows you to ensure that you do not create loops when you have redundant paths in the network. STP provides a single active path between two devices on a network in order to prevents loops from being formed when the Switch is interconnected via multiple paths.

STP uses a distributed algorithm to select a bridging device that serves as the root for the spanning tree network. It does this by selecting a root port on each bridging device to incur the lowest path cost when forwarding a packet from that device to the root device. It then selects a designated bridging device from each LAN which incurs the lowest path cost when forwarding a packet from that LAN to the root device. Next, all ports connected to designated bridging devices are assigned as designated ports. After determining the lowest cost spanning tree, it enables all root ports and designated ports, disabling all other ports. Network packets are therefore only forwarded between root ports and designated ports, eliminating any possible network loops. STP provides a single active path between two devices on a network in order to prevent loops from being formed when the Switch is interconnected via multiple paths.

Once a stable network topology has been established, all bridges listen for Hello Bridge Protocol Data Units (BPDUs) transmitted from the Root Bridge of the Spanning Tree. If a bridge does not receive a Hello BPDU after a predefined interval (known as the Maximum Age), the bridge will assume that the link to the Root Bridge is down and unavailable. This bridge then initiates negotiations with other bridges to reconfigure the network to reestablish a valid network topology.

To activate the Spanning Tree Protocol options for a device

1. Navigate to Policies > Policy Hierarchy > Switch Policy.
2. Select the System tab.
3. Enable the toggle bar, Spanning Tree Protocol Enable under the Spanning Tree Protocol section.
4. Select the Bridge Priority. When Switches or bridges are running STP, each is assigned a priority. After exchanging BPDUs, the Switch with the lowest priority value becomes the root bridge. The default value is: 32768.
5. Specify the Forward Delay in seconds. The minimum value is 4 and the maximum value is 30.
6. Specify the Maximum Age in seconds. The minimum value is 6 and the maximum value is 40.
7. Specify the Tx Hold Count. The minimum value is 1 and the maximum value is 10.
8. Choose the Hello Time in seconds from the drop-down. This is the amount of time between each bridge protocol data unit sent on a port.The options are one or two.

9. Specify the MST details. The VLAN ID number range is from 1 to 4094. Choose the Priority from the drop-down. When Switches or bridges are running STP, each is assigned a priority. After exchanging BPDUs, the Switch with the lowest priority value becomes the root bridge. The default value is: 32768. The range is from 0-61440. The bridge priority is a multiple of 4096.

   You can add more MST instances clicking on the add icon.