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Spanning Tree Protocol (STP) Interface Settings Configuration on ESW2-350G Switches

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Fri, 07/08/2016 - 11:40
Apr 26th, 2016
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Article ID: 3798

Objective

Spanning Tree Protocol (STP) is a network protocol that prevents the occurrence of loops in the topology. These loops, if caused in a network, use all the resources available on the network and reduce network efficiency.

STP interface settings are used to increase efficiency of STP on a per port basis. The fast link function of an edge port increases the speed of STP convergence because it sets a port to a forwarding state when a device is connected. The Root Guard and Bridge Protocol Data Unit (BPDU) Guard are used to control the STP topology. This extra control in the topology helps to prevent the occurrence of bridge loops.

This article explains how to configure STP interface settings on the ESW2-350G Switches.

Note: To configure STP on interfaces you need to enable STP globally. To do that, refer to article Configure Spanning Tree Protocol (STP) Status and Global Settings on ESW2-350G Switches for more information.

Applicable Devices

• ESW2-350G
• ESW2-350G-DC

Software Version

• 1.3.0.62

STP Interface Settings

STP Configuration

Step 1. Log in to the web configuration utility and choose Spanning Tree > STP Interface Settings. The STP Interface Settings page opens:

Step 2. Choose a type of interface from the Interface Type drop-down list.

• Port — From the Port drop-down lists choose the port to configure. This only affects the single port chosen.

• LAG — From the LAG drop down list choose the LAG to configure. This affects the group of ports defined in the LAG configuration.

Step 3. Click Go to bring up a list of ports or LAGs.

Step 4. Click the radio button of the Port or LAG you want to modify and click Edit

 

Step 5. (Optional) Click the radio button that corresponds to the desired interface type and choose the desired interface from the drop-down list in the Interface field.

Step 6. (Optional) Check Enable in the STP field to enable STP on the interface.

Step 7. Click the radio button that corresponds to the desired use of fast link in the Edge Port field. Fast link is used to automatically set a port or LAG to forwarding state when the port or LAG links up. Fast link optimizes the STP convergence.

• Enable — Enables fast link immediately.

• Auto — Enables fast link a few seconds after the interface becomes active. This allows STP to resolve loops before fast link is enabled.

• Disable — Disables fast link.

Step 8. (Optional) Check Enable in the Root Guard field to enable Root Guard on the interface. This option provides a way to enforce the root bridge placement in the network. Root Guard does not allow newly connected devices to set themselves as the root and thus affect the STP topology.

 

Step 9. (Optional) Check Enable in the BPDU Guard field to enable Bridge Protocol Data Unit (BPDU) Guard on the interface. BPDU Guard allows the user to enforce the STP domain borders on port and keep the active topology predictable. Devices that are connected to a port that have BPDU enabled cannot affect the STP topology. When the switch receives a BPDU on a port with BPDU Guard enabled, the port is disabled and a SNMP trap is generated.

 

Step 10. Click the radio button that corresponds to the desired option in the BPDU Handling field. This determines how BPDU packets are managed when STP is disabled on the port. BPDUs are used to transmit STP information.

• Use Global Settings — Uses the settings defined on the STP Status and Global Settings page.

• Filtering — Screens out  BPDU packets when STP is disabled on the interface.

• Flooding —  Forwards BPDU packets to all ports when STP is disabled on the interface.

 

Step 11. Path cost is calculated by the bandwidth between the switches. The root port is selected based on the path cost. The port with the lowest path cost to the root bridge becomes the root port. Click the radio button that corresponds to the desired path cost in the Path Cost field. 

• Use Default — Use the default cost generated by the system.

• User Defined — Enter a value for the path cost in the User Defined field.

 

Step 12. From the Priority drop-down list choose the priority value of the interface. The priority value determines port choice when a bridge has two ports which can form a loop. The lower the value, the higher the priority that the port has on the bridge.

Step 13. Click Apply.

Port Statistics

Step 1. Log in to the web configuration utility and choose Spanning Tree > STP Interface Settings. The STP Interface Settings page opens:

Step 2. Choose a type of interface from the Interface Type drop-down list.

• Port — From the Port drop-down lists choose the port to configure. This only affects the single port chosen.

• LAG — From the LAG drop down list choose the LAG to configure. This affects the group of ports defined in the LAG configuration.

Step 3. Click Go to bring up a list of ports or LAGs.

Step 4. Click the radio button of the Port or LAG you want to modify and click Edit.

The following fields display statistics of the interface.

• Port State — Current state of the specified port.

– Disabled — STP is disabled on the port. The port forwards traffic and learns MAC addresses.

– Blocking — The port is blocked. The port cannot forward traffic or learn MAC addresses. The port can forward BPDU data.

– Listening — The port cannot forward traffic and cannot learn MAC addresses.

– Learning — The port cannot forward traffic but it can learn new MAC addresses.

– Forwarding — The port can forward traffic and can learn new MAC addresses.

• Designated Bridge ID — The bridge priority and MAC address of the designated bridge.

• Designated Port ID — The priority and interface of the selected port.

• Designated Cost — The cost of the port that is part of the STP topology. Ports with lower costs are less likely to be blocked if STP detects loops.

• Forward Transitions — The number of times the port has changed from the blocking state to the forwarding state.

• Speed — The speed of the port.

• LAG — The LAG to which the port belongs. The LAG settings will override the port settings.

Copy Configuration from One Port to Another

Step 1. Log in to the web configuration utility and choose Spanning Tree > STP Interface Settings. The STP Interface Settings page opens:

Step 2. Click Copy Settings to copy the settings of one interface to others.

 

Step 3. Enter the interface(s) to which it needs to be copied in the provided field. Separate multiple interfaces or ranges with commas. Click Apply.

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