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Example: Configuring FEC 129 BGP Autodiscovery for VPWS

This example shows how to configure the virtual private wire service (VPWS), where remote provider edge (PE) devices are automatically discovered dynamically by BGP, and pseudowires are signaled by LDP using FEC 129. This arrangement reduces the configuration burden that is associated with statically configured Layer 2 circuits while still using LDP as the underlying signaling protocol.

Requirements

This example requires Junos OS Release 13.2 or later on the PE devices.

Overview

Because VPWS is a point-to-point service, FEC 129 VPWS routing instances are configured as instance-type l2vpn. As with FEC 129 VPLS, FEC 129 VPWS uses the l2vpn-id statement to define the Layer 2 VPN of which the routing instance is a member. The presence of the l2vpn-id statement designates that FEC 129 LDP signaling is used for the routing instance. The absence of l2vpn-id indicates that BGP signaling is used instead.

The point-to-point nature of VPWS requires that you specify the source access individual identifier (SAII) and the target access individual identifier (TAII). This SAII-TAII pair defines a unique pseudowire between two PE devices.

The SAII is specified with the source-attachment-identifier statement within the FEC 129 VPWS routing instance. You configure the source attachment identifier and the interfaces to associate with that source attachment identifier. Under each interface, you can configure the TAII with the target-attachment-identifier statement. If the configured target identifier matches a source identifier advertised by a remote PE device by way of a BGP autodiscovery message, the pseudowire between that source-target pair is signaled. If there is no match between an advertised source identifier and the configured target identifier, the pseudowire is not established.

Sample: VPWS Configuration with Multiple Interfaces and Sites

You can configure multiple interfaces within a site, because each SAII-TAII pair defines a unique pseudowire, as shown with pseudowires 1-2 and 1-3 in the sample configuration. Both the source and target access identifiers are 4-byte numbers and can only be configured in FEC 129 VPWS instances where the instance-type is l2vpn and the l2vpn-id configuration statement is present.

You can specify the source and target identifiers as plain unsigned integers in the range 1 through 4,292,967,295.

The Layer 2 circuit and Layer 2 VPN services allow many optional parameters to be included on a per-pseudowire basis. FEC 129 VPWS allows such parameters as MTU settings, community tagging, and inclusion of a control word, as shown in this sample configuration:

Sample: VPWS Configuration with Optional Configuration Parameters

When configured within the site, the defined parameters affect any pseudowire originating from that site. When configured under an interface, the defined parameters affect that single specific pseudowire. This allows you to manipulate the parameters across all pseudowires associated with a particular local site in one place in the configuration.

Like other point-to-point services, the interfaces configured as members of the FEC 129 VPWS instance must be configured for CCC encapsulation and the CCC address family, as shown here:

You can use vlan-ccc instead of ethernet-ccc.

To support the basic FEC 129 VPWS functionality, the BGP sessions on the PE devices also need to be configured with the BGP auto-discovery-only address family to allow exchange of the autodiscovery routes. If traditional BGP VPLS or Layer 2 VPN service is also provisioned on the PE devices, the address family l2vpn signaling is also required, as shown here:

The following configuration sample shows an FEC 129 VPWS routing instance with the operation, administration, and maintenance (OAM) (ping and BFD) configuration options:

Sample: VPWS Configuration with OAM

OAM options configured under protocols l2vpn apply to all sites and pseudowires in the routing instance. OAM options configured under a particular site apply to the pseudowires configured under that site. OAM options configured under a particular interface apply to the pseudowire configured under that interface.

Topology Diagram

Figure 1 shows the topology used in this example.

This example uses a simple topology with two PE devices and two customer edge (CE) devices.

Figure 1: Simple VPWS TopologySimple VPWS Topology

CLI Quick Configuration shows the configuration for all of the devices in Figure 1. The section #configuration646__vpws-fec-129-topo-step-by-step describes the steps on Device PE1.

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.

Device CE1

Device CE2

Device PE1

Device PE2

Procedure

Step-by-Step Procedure

To configure a FEC 129 VPWS:

  1. Configure the interfaces.

  2. Configure MPLS on the core-facing interface.

  3. Configure BGP.

  4. Configure an interior gateway protocol, such as IS-IS or OSPF.

    If you use OSPF, enable traffic engineering. Traffic engineering is supported by IS-IS by default.

  5. Configure LDP on the core-facing interface and on the loopback interface.

  6. Configure the VPWS routing instance.

    LDP listens for routes from instance.l2vpn.0 for any instance configured for FEC 129 VPWS. These routes are identified by the instance-type l2vpn statement in the routing instance and the presence of the l2vpn-id statement.

    Make sure that the target-attachment-identifier matches the source-attachment-identifier in the remote PE device’s corresponding site. In this example, the pseudowire is established between Device PE1 and Device PE2. Device PE1 uses SAI 1 and TAI 2, while Device PE2 uses the opposite, SAI 2 and TAI 1.

  7. Configure the autonomous system (AS) number.

  8. If you are done configuring the device, commit the configuration.

Results

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

Verification

Confirm that the configuration is working properly.

Verifying the Routes

Purpose

Verify that the expected routes are learned.

Action

From operational mode, enter the show route command.

Meaning

The output shows all the learned routes, including the autodiscovery (AD) routes.

Checking Connectivity Between the CE Devices

Purpose

Verify that Device CE1 can ping Device CE2.

Action

Meaning

The output shows that the VPWS is operational.

Checking the VPWS Connections

Purpose

Make sure that all of the FEC 129 VPWS connections come up correctly.

Action

Meaning

As expected, the connection is up. The output includes the source attachment ID and the target attachment ID.

Checking Connectivity Between the PE Devices

Purpose

Verify that Device PE1 can ping Device PE2. The ping mpls l2vpn fec129 command accepts SAIs and TAIs as integers or IP addresses and also allows you to use the CE-facing interface instead of the other parameters (instance, local-id, remote-id, remote-pe-address).

Action

Meaning

The output shows that the VPWS is operational.