Configure Spanning Tree Protocol (STP) Status and Global Settings on ESW2-350G Switches

Objective

Spanning-Tree Protocol (STP) prevents loops from being formed when switches or bridges are interconnected via multiple paths. Spanning-Tree Protocol implements the 802.1D IEEE algorithm by exchanging Bridge Protocol Data Unit (BPDU) messages with other switches to detect loops, and then removes the loop by shutting down selected bridge interfaces. This algorithm guarantees that there is one and only one active path between two network devices. The ESW2-350G Series Managed Switches are fixed configuration managed Ethernet switches. These switches provide 52 ports of Gigabit Ethernet connectivity.

The objective of this article is to explain how to configure STP status and global settings on ESW2-350G Switches.

If you are unfamiliar with terms in this document, check out Cisco Business: Glossary of New Terms.

Applicable Devices

• ESW2-350G
• ESW2-350G-DC

Software Version

• 1.3.0.62

Configuration of STP Status and Global Settings

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

Configuration of Global Settings

Step 1. Check the Enable check box in the Spanning Tree State field to enable STP.

Step 2. Click a radio button in the STP Operation Mode field to choose the desired STP operating mode.

• Classic STP — Provides a single path between any two end stations which avoids and eliminates loops.
• Rapid STP — Detects network topologies to provide faster convergence of the spanning tree. This is most effective when the network topology is naturally tree-structured, and therefore faster convergence might be possible. RSTP is enabled by default.
• Multiple STP — Detects Layer 2 loops and attempts to mitigate them by preventing the involved port from transmitting traffic. MSTP enables several STP instances, which makes it possible to detect and mitigate loops separately in each instance. MSTP provides full connectivity for packets allocated to any VLAN. In addition, MSTP transmits packets assigned to various VLANs through different multiple spanning tree (MST) regions. 

Step 3. In the BPDU Handling field, click the radio button according to the desired Bridge Protocol Data Unit (BPDU) handling. BPDU is used to transmit spanning tree information when STP is disabled on the port or the switch. 

• Filtering — Filters BPDU packets when spanning tree is disabled on an interface.
• Flooding — Floods BPDU packets when spanning tree is disabled on an interface.

Step 4. Click the radio button according to the desired path costs to the STP ports in the Path Cost Default Values field.

• Short — Specifies the range 1 through 65,535 for port path costs.
• Long — Specifies the range 1 through 200,000,000 for port path costs.

Configuration of Bridge Settings

Step 1. Enter a priority value in the Priority field. After the exchange of BPDUs, the device with the lowest priority becomes the Root Bridge. A Root Bridge is the bridge which becomes the active, in charge of the network and all other decisions, such as which port needs to be blocked and which port needs to be in the forward mode. In the case that all bridges use the same priority, their MAC addresses are used to determine which is the Root Bridge. The bridge priority value is provided in increments of 4096. The range is 0 - 61440.

Step 2. Enter the hello time in the Hello Time field. This is the interval in seconds that a root bridge waits between configuration messages. The range is 1 - 10 seconds.

Step 3. Enter the maximum age in the Max Age field. This is the interval in seconds that the switch waits without receiving a configuration message before the switch makes an attempt to redefine its own configuration. The range is 6 - 40 seconds.

Step 4. Enter the forward delay in the Forward Delay field. This is the interval in seconds that a bridge remains in a learning state before forwarding packets. The range is 4 - 30 seconds.

Step 5. Click Apply.

Designated Root Parameters

The following information is displayed in the Designated Root area:

• Bridge ID — The bridge priority concatenated with the MAC address of the switch.
• Root Bridge ID — The Root Bridge priority concatenated with the MAC address of the Root Bridge.
• Root Port — The port that offers the lowest cost path from this bridge to the Root Bridge. 
• Root Path Cost — The cost of the path from this bridge to the root.
• Topology Changes Counts — The total number of STP topology changes that have occurred.
• Last Topology Change — The time interval that elapsed since the last topology change occurred. The time is displayed in days/hours/minutes/ seconds format. 

Related Articles

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

Address Resolution Protocol (ARP) Manual Configuration on ESW2-350G Switches