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Example: Configuring Loop Prevention in VPLS Network Due to MAC Moves

 

This example shows how to prevent a loop in the VPLS network due to MAC moves between different physical interfaces.

When a MAC move is detected in the VPLS network, Junos OS allows the prevention of the loop in the network by disabling the interface using a base IFL or statistical approach algorithm.

Requirements

This example uses the following hardware and software components:

  • Four MX Series 5G Universal Routing Platforms

  • Junos OS Release 14.2 or later running on all devices

Before you begin:

  1. Configure the VPLS topology.

  2. Configure the VPLS routing instances.

  3. Enable VPLS MAC move action on a VPLS instance.

  4. Configure the routing and signaling protocols.

Overview

Starting with Junos OS Release 14.2, the loop creation in the VPLS network due to frequent MAC moves between different physical interfaces can be prevented by identifying and disabling such interfaces using the base IFL approach or statistical approach algorithm.

The base IFL approach algorithm is the primary approach. Base interface information is maintained for every MAC in the routing instance. If the MAC stays at the interface it was first learned for 300 seconds, then the interface-MAC association is considered to be stable, and this interface is considered as the base interface of the MAC. If the MAC move happens frequently between the local interface and the LSI interface while the base interface of the MAC is an LSI, then the local interface is considered to be looped and has to be disabled.

The statistical approach algorithm is the secondary approach used to disable the looped interface. If the MAC has not been learned for over 300 seconds at an interface, then it does not have a base interface and hence the statistical approach is used. If the MAC that has no base interface information( Base Learning interface is null) starts moving then the statistics of such MAC moves between different interfaces is learned. If the statistics show MAC moves from LSI to local interface or from local interface to local interface then the local interface is considered to be looped and is disabled.

Topology

In the topology shown in Figure 1, a loop was detected on Device PE1 in the VPLS network.

Figure 1: Example Loop Prevention Due to MAC Move in VPLS Network
Example Loop Prevention Due to MAC
Move in VPLS Network

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

This example uses the global-mac-move command, which replaced the vpls-mac-move command starting with Junos OS Release 17.4R1.

PE0

PE1

PE2

PE3

Configuring Device PE1

Step-by-Step Procedure

The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure Device PE1:

Note

Repeat this procedure for Routers PE0, PE2, and PE3 after modifying the appropriate interface names, addresses, and any other parameters for the router.

  1. Configure the interfaces.
  2. Configure the routing options.
  3. Configure the MPLS protocol on the interface.
  4. Configure the OSPF protocol.
  5. Configure the LDP protocols on the interfaces.
  6. Configure the threshold time and the threshold count to detect MAC moves.
  7. Configure VPLS MAC move parameters like cooloff time, statistical approach wait time, interface recovery time, and virtual MAC.
  8. Enable MAC move action on the interface for the VPLS instance vpls_1.

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show routing-options, and show routing-instances commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

If you are done configuring the device, enter commit from configuration mode.

Verification

Verify that the configuration is working properly.

Verifying the MAC Move in a VPLS Network

Purpose

Verify that the MAC move is observed in a VPLS network.

Action

From operational mode, run the show vpls mac-move-action command for Device PE1.

user@PE1> show vpls mac-move-action

Meaning

The output shows Instance name, Local interface and Algorithm used indicating that VPLS MAC Move is observed in a VPLS network.

Verifying the MAC Move in a VPLS Instance

Purpose

Verify that the MAC move is observed in a VPLS instance.

Action

From operational mode, run the show vpls mac-move-action instance instance-name command for Device PE1.

user@PE1> show vpls mac-move-action instance vpls_1

Meaning

The output shows Local interface, and Algorithm used indicating that VPLS MAC move has been observed in a VPLS instance.

Verifying the MAC Move Buffer in a VPLS Network

Purpose

Verify the MAC move buffer to monitor the MAC moves that are occurring in the VPLS network.

Action

From operational mode, run the show l2-learning mac-move-buffer command for Device PE1.

user@PE1> show l2-learning mac-move-buffer

Verifying the VPLS MAC Table for the Base IFL Approach Algorithm

Purpose

Verify the base learning interfaces for the MAC addresses. .

Action

From operational mode, run the show vpls mac-table extensive command to obtain extensive information of VPLS MAC table.

user@PE1> show vpls mac-table extensive

Meaning

The output of the command show vpls mac-table extensive shows the base learning interface of the MAC address.

Verifying That the Interface Is Disabled

Purpose

Verify that the base learning interface of the MAC address is disabled.

Action

From operational mode, run the show interfaces interface-name command for Device PE1.

user@PE1> show interfaces xe-1/3/1.600

Meaning

The flag link-layer-down in the output indicates that the interface is disabled.

Verifying the VPLS MAC Table for the Statistical Approach Algorithm

Purpose

Verify the VPLS MAC table for the statistical approach algorithm.

Action

From operational mode, run the show vpls mac-table extensive command for Device PE1.

user@PE1> show vpls mac-table extensive

Meaning

The Base learning interface is null which indicates that the statistical approach is in use.