Configuring the Rapid Spanning Tree Protocol

Introducing RSTP

Ethernet ports 3 and 4, located on the front of the 140 NOP 850 00 module, support the Rapid Spanning Tree Protocol (RSTP). is an OSI layer 2 protocol defined by IEEE 802.1D 2004. RSTP performs 2 services:

It creates a loop-free logical network path for Ethernet devices that are part of a topology that includes redundant physical paths.
It automatically restores network communication — by activating redundant links — in the event the network experiences an interruption of service.

NOTE: RSTP can take up to 50 ms to restore network communication in case of a service interruption. During this time, Ethernet packets may be dropped.

RSTP software, operating simultaneously in all network switches, obtains information from each switch, which enables the software to create a hierarchical logical network topology. RSTP is a flexible protocol that can be implemented on many physical topologies, including ring, mesh, or a combination of ring and mesh.

Use the RSTP tab of the Communication Settings window to configure RSTP for the embedded Ethernet switch in the 140 NOP 850 00 module. After you make your selection, click Apply to preserve your edit.

NOTE: RSTP can be implemented only when all network switches are configured to support RSTP.

Configuring RSTP Settings

The following setting can be viewed and edited in the Communication Settings → RSTP tab:

Setting	Description
RSTP Operational State: Bridge Priority	Select one of the following RSTP roles for the module: Root (0) Backup Root (4096) Participant (32768) (default) NOTE: Network switches running RSTP software periodically exchange information about themselves using special packets called Bridge Protocol Data Units (BPDUs), which act as a heartbeat. The Bridge Priority value is contained in the BPDU and establishes the relative position of the switch in the RSTP hierarchy.

Setting

Description

RSTP Operational State: Bridge Priority

Select one of the following RSTP roles for the module:

Root (0)
Backup Root (4096)
Participant (32768) (default)

NOTE: Network switches running RSTP software periodically exchange information about themselves using special packets called Bridge Protocol Data Units (BPDUs), which act as a heartbeat. The Bridge Priority value is contained in the BPDU and establishes the relative position of the switch in the RSTP hierarchy.