AT-GS950/16 Web Browser User Guide

AT-S108 Version 1.1.0 Software

Multiple Spanning Tree Protocol

 

This chapter provides the procedures for configuring Multiple Spanning Tree Protocol (MSTP). You can find an overview and configuration guidelines for this feature in MSTP Overview.

When you configure MSTP, the information should be entered in order on the following web pages:

» Multiple Spanning Tree Configuration

» VLAN Mapping

» Port Configuration

» Port Settings

» Topology Information

Multiple Spanning Tree Configuration

Head2

Head3

To configure the MSTP settings, perform the following procedure:

1. From the main menu on the left side of the page, select Bridge.
The Bridge folder expands.

2. From the Bridge folder, select the Spanning Tree folder.
The Spanning Tree folder expands.

3. From the Spanning Tree folder, select the MSTP folder.
The MSTP folder expands.

4. From the MSTP folder, select MSTP.

The Multiple Spanning Tree Configuration Page is displayed. See Figure 44.

 

Figure 44. Multiple Spanning Tree Configuration Page

The MSTP Configuration page allows you to configure the MSTP parameters as well as to view current settings of the feature.

In the upper portion of the page, you can set the following parameters:

Global MSTP Status - Set this field to Enable or Disable the MSTP feature on the switch. The Global MSTP Status must be set to Enable before the other MSTP configuration parameters can be set.

Both RSTP and BPDU Passthrough must be disabled before you enable MSTP.

 

Enabling or disabling MSTP causes the switch to temporarily stop switching Ethernet network traffic.

Maximum MST Instances - This specifies the maximum number of Multiple Spanning Tree Instances (MSTIs) that can be configured. The range is 1 - 31.

Bridge Priority - This parameter specifies the priority used in determining the regional root for a particular MSTI. For more information about Bridge Priority, see Table 8.

Region Name - This parameter specifies the region’s name where the bridge is a member. This name must be identical to the regional names specified on other switches in the same MSTP region. See Multiple Spanning Tree Regions for more information.

Region Revision - The parameter indicates the region’s revision and must be identical to the regional names specified on other switches in the same MSTP region. See Multiple Spanning Tree Regions for more information.

Dynamic Path Cost Calculation - This parameter is either True or False. When set to True, the path cost of each port on the bridge is dynamically calculated based on the port speed. If the parameter is set to False, the path cost of the bridge is based on the initial value of the port speed.

In the middle section of the page, the status of the MSTP bridge parameters are shown. The bottom section of the page is where you can adjust the values of these parameters. The following fields are listed:

Maximum Age - The Maximum Age defines the amount of time a port will wait for STP/RSTP information. MSTP uses this parameter when interacting with STP/RSTP domains on the boundary ports. Its range is 6 - 40 seconds.

Forward Delay - The Forward Delay defines the time that the bridge spends in the listening and learning states. Its range is
4 - 30 seconds.

Maximum Hop Count - The Maximum Hop Count is a parameter set in a BPDU packet when it originates. It is decremented by 1 each time it is retransmitted by the next bridge. When the Hop Count value reaches zero, the bridge drops the BPDU packet. Its range is 6 - 40 hops.

Transmit Hold Count - The Transmit Hold Count specifies the maximum number of BPDUs that the bridge can send per second. Its range is 1 - 10.

5. Once you have configured the parameters, click Apply.

6. From the main menu on the left side of the page, select Save Configuration to Flash to permanently save your changes.

VLAN Mapping

You can create, modify and delete MSTP settings with the procedures in the following sections:

» Open MSTP VLAN Mapping Page

» Create VLAN Mapping to MST Instance.

» Modify MST Instance.

» Delete MST Instance.

Open MSTP VLAN Mapping Page

1. From the main menu on the left side of the page, select Bridge.
The Bridge folder expands.

2. From the Bridge folder, select the Spanning Tree folder.
The Spanning Tree folder expands.

3. From the Spanning Tree folder, select the MSTP folder.
The MSTP folder expands.

4. From the MSTP folder, select MSTP VLAN Mapping.
The MSTP VLAN Mapping Page is displayed. See Figure 45.

 

Figure 45. MSTP VLAN Mapping Page

Create VLAN Mapping to MST Instance

1. Enter the MSTP Instance ID. You can enter any number of MSTP IDs up to the maximum MSTP ID. See Multiple Spanning Tree Configuration for more information.

2. Enter an existing VLAN ID in the ADD VLAN field that you want to associate with the MSTI ID entered in step 4.

3. Click Add.
The Instance ID and the Mapped VLAN will be displayed in the table on the page.

4. You may add as many VLANs to one MST Instance by repeating steps 4 through 6.

5. From the main menu on the left side of the page, select Save Configuration to Flash to permanently save your changes.

Modify MST Instance

If you wish to modify a MST Instance, you must first delete the instance and then redefine it. Refer to Create VLAN Mapping to MST Instance for more information.

Delete MST Instance

1. In the Action column of the table, click on Delete for the MST Instance that want to delete.
The instance is deleted along with the mapped associations to the VLANs that are listed.

2. From the main menu on the left side of the page, select Save Configuration to Flash to permanently save your changes.

Port Configuration

To configure the MSTP parameters for each of the ports, perform the following procedure:

1. From the main menu on the left side of the page, select Bridge.
The Bridge folder expands.

2. From the Bridge folder, select the Spanning Tree folder.
The Spanning Tree folder expands.

3. From the Spanning Tree folder, select the MSTP folder.
The MSTP folder expands.

4. From the MSTP folder, select MSTP Port Configuration.
A partial view of the AT-GS950/16 MSTP Port Configuration Page is displayed. See Figure 46.

 

 

Figure 46. AT-GS950/16 MSTP Port Configuration Page

You may choose a port and configure its MSTP parameters on this page. The following information is displayed:

Port - Indicates ports 1 through 16 on the AT-GS950/16 switch. Use the All row to apply the same settings for the Point-to-Point Status, Edge Port, MSTP Status, Protocol Migration, AutoEdge Status, Restricted Role, Restricted TCN fields to all the ports on your switch.

Path Cost - Specifies the cost of a port to the root.

Priority - Specifies the spanning tree port priority.

PointToPoint Status - Indicates if the port is connected to another network device (point-to-point) in the network topology. See Point-to-Point and Edge Ports for more information.

ForcedTrue - The port is connected to a network device in the network topology.

ForcedFalse - The port is not connected to a network device in the network topology.

Auto - The switch will automatically determine the port type.

Edge Port - Indicates if a port is connected to an edge device in the network topology or not. See Point-to-Point and Edge Ports for more information.

True - The port is connected to an edge device and the port will always be in a forwarding state.

False - The port is not connected to an edge device.

MSTP Status - Indicates if MSTP is Enabled or Disabled.

Enabled - MSTP is active on the port.

Disabled - MSTP is inactive on the port.

Protocol Migration - A switch running MSTP supports a built-in protocol migration mechanism that enables it to inter-operate with legacy 802.1D switches.

True - The switch is able to inter-operate with 802.1D BPDU packets.

False - This switch can only operate with RSTP and MSTP packets.

Hello Time - The Hello Time is frequency with which the root bridge sends out a BPDU. See Hello Time and Bridge Protocol Data Units (BPDU) for more information.

AutoEdge Status - This parameter allows the switch to detect if the port functioning as an edge port.

Restricted Role - This parameter prevents the port from becoming a root port.

True - The port is prevented from being a root port or a port that is used to communicate with the root bridge.

False - This switch can only operate with RSTP and MSTP packets.

The net effect of setting all ports on the switch to True is that it forces the switch into the role of the root bridge regardless of other path costs in the network.

Restricted TCN - The Restricted TCN parameter does not allow Topology Change Notification (TCN) BPDUs to be processed on the port.

True - The port cannot process receive/transmit TCN BPDUs.

False - The port can process receive/transmit TCN BPDU packets.

5. Once you have configured the parameters, click Apply in the Action column.

6. If you choose to change the MSTP port configuration for other ports, repeat steps 4 and 5.

7. From the main menu on the left side of the page, select Save Configuration to Flash to permanently save your changes.

Port Settings

To configure the MSTP port settings, perform the following procedure:

1. From the main menu on the left side of the page, select Bridge.
The Bridge folder expands.

2. From the Bridge folder, select the Spanning Tree folder.
The Spanning Tree folder expands.

3. From the Spanning Tree folder, select the MSTP folder.
The MSTP folder expands.

4. From the MSTP folder, select MSTP Port Settings.
The MSTP Port Settings Page is displayed. See Figure 47.

 

Figure 47. MSTP Port Settings Page

You may choose a port and configure its MSTP parameters on this page. The following information is displayed:

Port - Indicates ports 1 through 16 on the AT-GS950/16 switch. Use the All row to apply the same settings for the Port State field to all the ports on your switch.

MSTP Instance ID - Indicates the MSTP Instance that associated with this port.

Port State - This parameter activates or deactivates the port. Select one of the following choices from the pull-down menu:

Enable - Allows the port to forward packets.

Disable - Does not allows the port to forward packets.

Priority - This is the port priority used by MSTP in calculating path costs when two ports on the switch have the same port cost.

Cost - This is the port cost used by MSTP when calculating path cost to the root bridge.

5. Once you have configured the parameters, click Apply in the Action column.

6. If you choose to change the MSTP port settings for other ports, repeat steps 4 and 5.

7. From the main menu on the left side of the page, select Save Configuration to Flash to permanently save your changes.

Topology Information

To configure the MSTP port settings, perform the following procedure:

1. From the main menu on the left side of the page, select Bridge.
The Bridge folder expands.

2. From the Bridge folder, select the Spanning Tree folder.
The Spanning Tree folder expands.

3. From the Spanning Tree folder, select the MSTP folder.
The MSTP folder expands.

4. From the MSTP folder, select MSTP Port Settings.
A partial view of the AT-GS950/16 Topology Information Page is displayed. See Figure 48.

 

Figure 48. AT-GS950/16 Topology Information Page

The following information displayed on this page shows the current status of MSTP for each port:

Port - Indicates ports 1 through 16 on the AT-GS950/16 switch.

Designated Root - The designated root bridge to which the switch’s root port is actively connected.

Root Priority - This parameter specifies the priority used in determining the regional root for a particular MSTI. For more information, see Table 8.

Designated Bridge - The bridge providing the least cost path to the root bridge from a network segment.

Designated Port - The port providing the least cost path to the root bridge from a network segment.

Designated Cost - The cost from the designated bridge to the root bridge.

Regional Root - The root bridge of the MST instance.

Regional Root Priority - The priority of the regional root port.

Regional Path Cost - The path cost from the regional root port to the regional root bridge.

Type - This specifies the regional port type which can be either a point-to-point or an edge type port. See Point-to-Point and Edge Ports for more information.

Role - Indicates the port’s role which may be Disabled, Root, Designated, Backup, or Alternate. See the parameter definitions described for Role under Configure the Basic RSTP Port Settings for more information.

Port State - Indicates the ports spanning tree state which may be Blocking, Listening, Learning, Forwarding, Disabled. See the parameter definitions described for Port State under Configure the Basic RSTP Port Settings for more information.