RSTP Tab

Introduction

The Ethernet DEVICE NETWORK ports on the front of the M580 CPU support rapid spanning tree protocol (RSTP). RSTP is an OSI layer 2 protocol defined by IEEE 802.1D 2004. RSTP performs these services:

RSTP creates a loop-free logical network path for Ethernet devices that are part of a topology that includes redundant physical paths. When either DEVICE NETWORK port (ETH 2 or ETH 3) on the CPU is disconnected, the RSTP service directs traffic to the other port.
RSTP automatically restores network communication by activating redundant links when a network event causes a loss of service.

NOTE: When an RSTP link is disconnected, the RSTP service acts on an event and forwards traffic through the correct port. During this re-connect time (50ms max), some packets may be lost.

The RSTP service creates a loop-free logical network path for Ethernet devices that are part of a topology that includes redundant physical paths. When the network experiences a loss of service, the RSTP-enabled module automatically restores network communication by activating redundant links.

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

Changing these parameters can affect sub-ring diagnostics, RIO determinism, and network recovery times.

Assign the Bridge Priority for RIO/DIO Scanner Service

A bridge priority value is used to establish the relative position of a switch in the RSTP hierarchy. Bridge priority is a 2-byte value for the switch. The valid range is 0 ... 65535, with a default of 32768 (the midpoint).

Assign the Bridge Priority on the RSTP page:

Step	Action
1	Select RSTP to see the RSTP Operational State .
2	Select a Bridge Priority from the drop-down list in the RSTP Operational State area: Root (0) (default) Backup Root (4096) Participant (32768)
3	Finish the configuration: OK: Assign the Bridge Priority, and close the window. Apply: Assign the Bridge Priority , and keep the window open.

Step

Action

1

Select RSTP to see the RSTP Operational State .

2

Select a Bridge Priority from the drop-down list in the RSTP Operational State area:

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

3

Finish the configuration:

OK: Assign the Bridge Priority, and close the window.
Apply: Assign the Bridge Priority , and keep the window open.

RSTP Parameters for CPUs with RIO and DIO Scanner Service

RSTP tab:

Field	Parameter	Value	Comment
RSTP Operational State	Bridge Priority	Root (0)	default
		Backup Root (4096)	–
		Participant (32768)	–

RSTP Parameters for CPUs without RIO Scanner Service (DIO Scanner Service Only)

RSTP tab:

Field	Parameter	Value	Comment
RSTP Operational State	Bridge Priority	Root(0)	–
		Backup Root(4096)	–
		Participant(32768)	default
Bridge parameters	Force version	2	You cannot edit this value.
	Forward delay (ms)	21000
	Maximum Age Time (ms)	40000
	Transmit Hold Count	40
	Hello Time (ms)	2000
Port 2 Parameters	–	–	You cannot edit these field parameters.
Port 3 Parameters	–	–	You cannot edit these field parameters.