Port

Note: Deactivate the Spanning Tree protocol for the ports connected to a HIPER-Ring, Fast HIPER-Ring, or Ring/Network coupling, because Spanning Tree and Ring Redundancy or Ring/Network coupling affect each other.
Activate the MRP compatibility in an MRP-Ring if you want to use RSTP and MRP in combination.
If you combine RSTP with an MRP-Ring, you must give the devices in the MRP-Ring a better (i.e. numerically lower) RSTP bridge priority than the devices in the connected RSTP network. You thus help avoid a connection interruption for devices outside the Ring.

The MSTI tabs in the dialog allow you to manage the individual Multiple Spanning Tree Instances. The tab is named MSTI, followed by the number of the instance, e.g. “MSTI 2”.

Tab. Port-related STP settings and displays, CIST

Parameters

Meaning

Possible values

Default setting

Tab „CIST“

Port configuration and information on the global MSTI (IST) and the CST.

   

Module.Port

Port identification using module and port numbers of the device, e.g. 2.1 for port one of module two.

STP active

Here you can switch Spanning Tree on or off for this port. If Spanning Tree is activated globally and switched off at one port, this port does not send STP-BPDUs and drops any STP-BPDUs received.

Note: If you want to use other layer 2 redundancy protocols such as HIPER-Ring or Ring/Network coupling in parallel with Spanning Tree, make sure you switch off the ports participating in these protocols in this dialog for Spanning Tree. Otherwise the redundancy may not operate as intended or loops can result.

On, Off

On

Port status (read only)

Displays the STP port status with regard to the global MSTI (IST).

discarding, learning, forwarding, disabled, manualForwarding, notParticipate

-

Port Role (read only)

Displays the STP port role with regard to the global MSTI (IST).

root

alternate

designated

backup

master

disabled

-

Port path costs

Enter the path costs with regard to the global MSTI (IST) to indicate preference for redundant paths. If the value is 0, the Switch automatically calculates the path costs for the global MSTI (IST) depending on the transmission rate.

0 - 200000000

0 (automatically)

Port priority

Here you enter the port priority (the four highest bits of the port ID) with regard to the global MSTI (IST) as a decimal number of the highest byte of the port ID.

16 ≤ n∙16 ≤ 240

128

Received bridge ID (read only)

Displays the remote bridge ID from which this port last received an STP-BPDU.a

Bridge identification
(format ppppp / mm mm mm mm mm mm)

-

Received port ID (read only)

Displays the port ID at the remote bridge from which this port last received an STP-BPDU.a

Port ID,
format pn nn,
with p: port priority / 16,
nnn: port No., (both hexadecimal)

-

Received path costs (read only)

Displays the path costs of the remote bridge from its root port to the CIST root bridge.a

0-200000000

-

Admin Edge Port

Only activate this setting when a terminal device is connected to the port (administrative: default setting). Then the port immediately has the forwarding status after a link is set up, without first going through the STP statuses. If the port still receives an STP-BPDU, the device blocks the port and clarifies its STP port role. In the process, the port can switch to a different status, e.g. forwarding, discarding, learning.

Deactivate the setting when the port is connected to a bridge. After a link is set up, the port then goes through the STP statuses first before taking on the forwarding status, if applicable.

This setting applies to all MSTIs.

active (box selected), inactive (box empty)

inactive

Auto Edge Port

The device only considers the Auto Edge Port setting when the Admin Edge Port parameter is deactivated.
If Auto Edge Port is active, after a link is set up the device sets the port to the forwarding status after 1.5 ∙ Hello Time (in the default setting 3 s).
If Auto Edge Port is deactivated, the device waits for the Max Age instead (in the default setting 20 s).
This setting applies to all MSTIs.

active (box selected),
inactive (box empty)

active

Oper Edge Port

The device sets the “Oper Edge Port” condition to true if it has not received any STP-BPDUs, i.e. a terminal device is connected. It sets the condition to false if it has received STP-BPDUs, i.e. a bridge is connected.

This condition applies to all MSTIs.

true, false

-

Oper PointToPoint

The device sets the “Oper point-to-point” condition to true if this port has a full duplex condition to an STP device. Otherwise it sets the condition to false (e.g. if a hub is connected).
The point-to-point connection makes a direct connection between 2 RSTP devices. The direct, decentralized communication between the two bridges results in a short reconfiguration time.
This condition applies to all MSTIs.

true, false

The device determines this condition from the duplex mode:
FDX: true
HDX: false

 

Tab. Port-related STP settings and displays, guards

Parameters

Meaning

Possible values

Default setting

Tab „Guards“

Protective settings for the ports.

   

Module.Port

Port identification using module and port numbers of the device, e.g. 2.1 for port one of module two.

Root Guard

The “Root Guard” setting is only relevant for ports with the STP role designated.
If such a port receives an STP-BPDU with better path information on the root that what the device knows, the device discards the BPDU and sets the port status to discarding, instead of assigning the port the STP port role root.

Thus the device helps protect your network from attacks with STP-BPDUs that try to change the topology, and from incorrect configurations.

If there are no STP-BPDUs with better path information on the root, the device resets the transmission status of the port according to the port role.

Note: The “Root Guard” and “Loop Guard” settings are mutually exclusive. If you activate one setting when the other is already active, the device switches off the other one.

active (box selected), inactive (box empty)

inactive

TCN Guard

If the “TCN Guard” setting is active (TCN: Topology Change Notification) the port ignores the topology change flag in the STP-BPDUs received, which is reporting a topology change.

Thus the device protects your network from attacks with STP-BPDUs that try to change the topology.

If the “TCN Guard” setting is inactive, the device follows the protocol in reacting to the STP-BPDUs received: it deletes its address table and forwards the TCN information.

Note: If the received BPDU contains other information apart from the topology change flag that causes a topology change, the device processes the BPDU even if the TCN guard is activated. Example: the device receives better path information for the root than that already known.

active (box selected), inactive (box empty)

inactive

Loop Guard

The “Loop Guard” setting is only meaningful for ports with the STP role alternate, backup or root. If the “Loop Guard” setting is active and the port has not received any STP-BPDUs for a while, the device sets the port to the discarding condition (port sends no more data).
The device also sets the port to what is known as the “loop inconsistent status” and displays this in the “Loop Status” column.
The device prevents a potential loop if no more STP-BPDUs are received if, for example, you switch STP off on the remote device, or the link only fails in the receiving direction.
When the port receives BPDUs again, the device resets the loop status of the port to false, and the transmission status of the port according to the port role.
If the “Loop Guard” setting is inactive, however, the device sets the port to the forwarding status when STP-BPDUs have not been received.

Note: The “Root Guard” and “Loop Guard” settings are mutually exclusive. If you activate one setting when the other is already active, the device switches off the other one.

active (box selected), inactive (box empty)

inactive

Loop State (read only)

Display the status of the Loop Status.

The device sets the loop status of the port to true if the “Loop Guard” setting is active at the port and the port is not receiving any more STP-BPDUs.

Here the device leaves the port in the discarding transmission status, thus helping to prevent a potential loop.

When the port receives STP-BPDUs again, the device resets the loop status to false.

true, false

-

Transitions to Loop Status (read only)

Counts how often the device has set the port to the loop status (“Loop Status” column true).

0 - 4294967295 (232-1)

0

Transitions from Loop Status

Counts how often the device has set the port out of the loop status (“Loop Status” column true).

0 - 4294967295 (232-1)

0

BPDU Guard Effect (read only)

The “BPDU Guard Effect” status is only relevant for edge ports (ports with the “Admin Edge Port” status true), and only if the “BPDU Guard” global function is active 'Global Spanning Tree settings, local bridge parameters'.
When such a port receives any random STP-BPDU, the device sets the port's “BPDU Guard Effect” status to true and its transmission status to discarding.

Thus the device helps you protect your network at terminal device ports from incorrect configurations or attacks with STP-BPDUs that try to change the topology.

To return the port to a normal transmitting status from the locked status, break and reconnect the link, or switch the “Admin Edge Port” port setting off and on again.

true, false

-


Tab. Port-related STP settings and displays, per MSTI

Parameters

Meaning

Possible values

Default setting

“MSTI <ID>” tab

Port configuration and information on the selected MSTI.

Note: Note: the device only displays the MSTI ... tab if you have configured at least 1 MST instance.
   

Port status (read only)

Displays the STP port status with regard to the current MSTI.

discarding, learning, forwarding, disabled, manualForwarding, notParticipate

-

Port role (read only)

Displays the STP port role with regard to the current MSTI.

root, alternate, designated, backup, master, disabled

-

Port path costs

Enter the path costs with regard to the current MSTI to indicate preference for redundant paths. If the value is 0, the Switch automatically calculates the path costs depending on the transmission rate.

0 - 200000000

0 (automatically)

Port priority

Here you enter the port priority (the four highest bits of the port ID) with regard to the current MSTI as a decimal number of the highest byte of the port ID.

16 ≤ n*16 ≤ 240

128

Received bridge ID (read only)

Displays the remote bridge ID of the current MSTI from which this port last received a BPDU.a.

Bridge identification
(format ppppp / mm mm mm mm mm mm)

-

Received port ID (read only)

Displays the port ID of the remote bridge of the current MSTI from which this port last received a BPDU.a

Port ID,
format pn nn,
with p: port priority / 16,
nnn: port No., (both hexadecimal)

-

Received path costs (read only)

Displays the path costs of the remote bridge from its root port to the root bridge of the current MSTI.a.

0-200000000

-


Buttons

Tab. Buttons (Forts.)

Button

Meaning

“Set”

Transfers the changes to the volatile memory (RAM) of the device. To permanently save the changes, open the Basic Settings:Load/Save dialog, select the location to save the configuration, and click “Save”.

“Reload”

Updates the fields with the values that are saved in the volatile memory (RAM) of the device.

“Help”

Opens the online help.