Rapid Spanning Tree Protocol (RSTP) Interface Settings on ESW2-550X Switches

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 the network efficiency.

Rapid Spanning Tree Protocol (RSTP) is an enhanced version of STP, that provides a faster convergence to obtain a loop free topology. It is most effective when the network topology is naturally tree-structured, and therefore faster convergence might be possible.

This article explains how to configure RSTP interface settings on the ESW2-550X stackable managed switches.

Applicable Devices

• ESW2-550X
• ESW2-550X-DC

Software Version

• v1.2.9.44

RSTP Interface Settings

Before the configuration of the RSTP interface settings, you should choose the Rapid STP mode of operation from Spanning Tree > STP Status & Global Settings. Refer to article Configure Spanning Tree Protocol (STP) Status and Global Settings on ESW2-550X Switches for more information.

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

Step 2. Choose the desired interface from the Interface drop-down list. Click Go.

Individual Interface Settings

Step 1. Click the radio button of the Port or LAG you want to modify and click Edit. The Edit RSTP Interface Settings page opens:

Step 2. (Optional) In the Interface field click the desired radio button .

• Unit/Slot and Port — The unit identifies the whether the switch is active or a member in the stack (unit 1 is active and unit 2 is a member). The slot identifies whether the switch is ESW2-550 or ESW2-550X (slot 1 is ESW2-550 and slot 2 is ESW2-550X). Choose the desired option from the Unit/Slot drop-down list and choose the desired port from the Port drop-down list. If you are unfamiliar with the terms used, check out Cisco Business: Glossary of New Terms.

• LAG — Choose the desired LAG from the LAG drop-down list. A Link Aggregate Group (LAG) is used to link multiple ports together. LAGs multiply bandwidth, increase port flexibility, and provides link redundancy between two devices to optimize port usage

Step 3. Click the desired radio button in the Point to Point Administrative Status field. The available options are:

• Enable — When it is enabled, the port acts as a RSTP edge port.

• Disable — The edge port is not a RSTP port, STP is used in the port.

• Auto — The port decides on its own with the help of RSTP BPDUs. BPDUs are used to transmit spanning tree information.

The following information is displayed.

• Point to Point Operational Status — The status of  the Point to Point Administrative Status field.

• Role — The role of the port assigned by the STP to provide STP paths. The available roles are:

– Root — It has the lowest cost path to forward packets to the Root Bridge.

– Designated — The interface through which the bridge is connected to the LAN, which provides the lowest cost path from the LAN to the Root Bridge.

– Alternate — Provides an alternate path to the Root Bridge from the root interface.

– Backup — Provides a backup path to the designated port. Backup ports are also used when a LAN has two or more established connections to a shared segment.

– Disabled — The port is not participating in Spanning Tree.

• Mode — The current mode of spanning tree such as Classic STP or RSTP.

• Fast Link Operational Status — Status of the edge port.

– Enable — Edge port is enabled.

– Disable — Edge port is disabled.

– Auto — Once the interface is active for a few seconds the edge port is enabled.

• Port Status — The STP status on the port chosen.

– Disabled — STP is disabled on the port.

– 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.

Step 4. Click Apply and then click Close to return to the RSTP Interface Settings Table.

Step 5. (Optional) If a link partner is discovered by the use of STP, then this test is used to discover if the STP in the link partner still exists, and if so whether it is migrated to RSTP or MSTP. If the link partner is in STP the device communicates with STP, if it has been migrated to RSTP or MSTP, the device also changes to RSTP or MSTP respectively.

Copy Settings to Multiple Interfaces

Step 1. Click Copy Settings to copy the settings of one interface to others. The Copy Settings page opens:

Step 2. Enter the interface(s) or range(s) of interface to which the settings are applied in the provided field.

Step 3. Click Apply.