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Configuring a Spanning Tree—Quick Configuration

Juniper devices provide Layer 2 loop prevention through Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), and Multiple Spanning Tree Protocol (MSTP). You can configure bridge protocols data unit (BPDU) protection on interfaces to prevent them from receiving BPDUs that could result in STP misconfigurations, which could lead to network outages.

You can use the J-Web Quick Configuration to add a spanning tree or to edit or delete an existing spanning tree.

To access the Spanning Tree Quick Configuration:

  1. In the J-Web user interface, select Configure>Switching>Spanning Tree.

    The Spanning Tree Configuration page displays a list of existing spanning trees. If you select a specific spanning tree, the specific spanning tree details are displayed in the General and Interfaces tabs.

  2. Click one of the following:

    When you are adding a spanning tree, select a protocol name:

    Select the Ports tab to configure the ports associated with this spanning tree. Click one of the following:

    When you are adding or editing a spanning-tree port, enter information as described in Table 177.

  3. Click one:

Table 174: STP Configuration Parameters

Field

Function

Action

Protocol Name

Displays the spanning-tree protocol.

View only.

Disable

Disables STP on the interface.

To enable this option, select the check box.

BPDU Protect

Specifies that BPDU blocks are to be processed.

To enable this option, select the check box.

Bridge Priority

Specifies the bridge priority. The bridge priority determines which bridge is elected as the root bridge. If two bridges have the same path cost to the root bridge, the bridge priority determines which bridge becomes the designated bridge for a LAN segment.

Select a value.

Forward Delay

Specifies the number of seconds an interface waits before changing from spanning-tree learning and listening states to the forwarding state.

Enter a value from 4 through 30 seconds.

Hello Time

Specifies time interval in seconds at which the root bridge transmits configuration BPDUs.

Enter a value from 1 through 10 seconds.

Max Age

Specifies the maximum aging time in seconds for all MST instances. The maximum aging time is the number of seconds a switch waits without receiving spanning-tree configuration messages before attempting a reconfiguration.

Enter a value from 6 through 40 seconds.

Table 175: RSTP Configuration Parameters

Field

Function

Action

Protocol Name

Displays the spanning-tree protocol.

View only.

Disable

Specifies whether RSTP must be disabled on the interface.

To enable this option, select the check box.

BPDU Protect

Specifies that BPDU blocks are to be processed.

To enable this option, select the check box.

Bridge Priority

Specifies the bridge priority. The bridge priority determines which bridge is elected as the root bridge. If two bridges have the same path cost to the root bridge, the bridge priority determines which bridge becomes the designated bridge for a LAN segment.

Select a value.

Forward Delay

Specifies the number of seconds a port waits before changing from its spanning-tree learning and listening states to the forwarding state.

Enter a value from 4 through 30 seconds.

Hello Time

Specifies the hello time in seconds for all MST instances.

Enter a value from 1 through 10 seconds.

Max Age

Specifies the maximum aging time in seconds for all MST instances. The maximum aging time is the number of seconds a switch waits without receiving spanning-tree configuration messages before attempting a reconfiguration.

Enter a value from 6 through 40 seconds.

Table 176: MSTP Configuration Parameters

Field

Function

Action

Protocol Name

Displays the spanning-tree protocol.

View only.

Disable

Specifies whether MSTP must be disabled on the interface.

To enable this option, select the check box.

BPDU Protect

Specifies that BPDU blocks are to be processed.

To enable this option, select the check box.

Bridge Priority

Specifies the bridge priority. The bridge priority determines which bridge is elected as the root bridge. If two bridges have the same path cost to the root bridge, the bridge priority determines which bridge becomes the designated bridge for a LAN segment.

Select a value.

Forward Delay

Specifies the number of seconds a port waits before changing from its spanning-tree learning and listening states to the forwarding state.

Enter a value from 4 through 30 seconds.

Hello Time

Specifies the hello time in seconds for all MST instances.

Enter a value from 1 through 10 seconds.

Max Age

Specifies the maximum aging time for all MST instances. The maximum aging time is the number of seconds a switch waits without receiving spanning-tree configuration messages before attempting a reconfiguration.

Enter a value from 6 through 40 seconds.

Configuration Name

MSTP region name carried in the MSTP bridge protocol data units (BPDUs).

Enter a name.

Max Hops

Maximum number of hops a BPDU can be forwarded in the MSTP region

Enter a value from 1 through 255.

Revision Level

Revision number of the MSTP region configuration.

Enter a value from 0 through 65535.

MSTI tab

MSTI Id

Specifies the multiple spanning-tree instance (MSTI) identifier. MSTI IDs are local to each region, so you can reuse the same MSTI ID in different regions.

Click one:

  • Add—Creates a MSTI.
  • Edit—Edits an existing MSTI.
  • Delete—Deletes an existing MSTI.

Bridge Priority

Specifies the bridge priority. The bridge priority determines which bridge is elected as the root bridge. If two bridges have the same path cost to the root bridge, the bridge priority determines which bridge becomes the designated bridge for a LAN segment.

Select a value.

VLAN

Specifies the VLANs for the MSTI.

Click one:

  • Add—Selects VLANs from the list.
  • Remove—Deletes the selected VLAN.

Interfaces

Specifies the interface for the MSTP protocol.

Click one:

  • Add—Selects interfaces from the list.
  • Edit—Edits the selected interface.
  • Remove—Deletes the selected interface.

Table 177: Spanning-Tree Ports Configuration Details

Field

Function

Action

Interface Name

Specifies the interface for the spanning-tree protocol type.

Select an interface.

Cost

Specifies the link cost to control which bridge is the designated bridge and which interface is the designated interface.

Enter a value from 1 through 200,000,000.

Priority

Specifies the interface priority to control which interface is elected as the root port.

Select a value.

Disable Port

Disables the spanning-tree protocol type on the interface.

Select to disable the spanning-tree protocol type.

Edge

Configures the interface as an edge interface. Edge interfaces immediately transition to a forwarding state.

Select to configure the interface as an edge interface.

No Root Port

Specifies an interface as a spanning-tree designated port. If the bridge receives superior STP bridge protocol data units (BPDUs) on a root-protected interface, that interface transitions to a root-prevented STP state (inconsistency state) and the interface is blocked. This blocking prevents a bridge that should not be the root bridge from being elected the root bridge. When the bridge stops receiving superior STP BPDUs on the root-protected interface, interface traffic is no longer blocked.

Select to configure the interface as a spanning-tree designated port.

Interface Mode

Specifies the link mode.

Select one:

  • Point to Point—For full-duplex links, select this mode.
  • Shared—For half-duplex links, select this mode.

BPDU Timeout Action

Specifies the BPDU timeout action for the interface.

Select one:

  • Alarm—Generate a system log file message to record the loop protection event.
  • Block—Configure loop protection on a specific interface.

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