Example: Configuring BGP Autodiscovery for LDP VPLS

This example uses the following hardware and software components:

• Four MX Series 5G Universal Routing Platforms

• Junos OS Release 10.4R2 or later

If you are using M Series or T Series routers, the PE routers must have either virtual loopback tunnel (vt) interfaces or label-switched interfaces (LSIs). On M Series and T Series routers, VPLS uses tunnel-based PICs to create virtual ports on vt interfaces. If you do not have a tunnel-based PIC installed on your M Series or T Series router, you can still configure VPLS by using LSIs to support the virtual ports. Use of LSIs requires Ethernet-based PICs installed in an Enhanced Flexible PIC Concentrator (FPC).

You do not need to use routers for the CE devices. For example, the CE devices can be EX Series Ethernet Switches.

All PE routers in a VPLS network operate like a large, distributed Ethernet switch to provide Layer 2 services to attached devices. This example shows a minimum configuration for PE routers and CE devices to create an autodiscovered VPLS network. The topology consists of five routers: two PE routers, two CE routers, and an optional route reflector (RR). The PE routers use BGP to autodiscover two different VPLS instances that are configured on both PE routers. Then the PE routers use LDP to automatically signal two pseudowires between the discovered end points. Finally, the PE routers bring up both VPLS instances for forwarding traffic. Each CE device is configured with two VLANs, with each VLAN belonging to different VPLS instances in the PE routers.

This example includes the following settings:

• auto-discovery-only—Allows the router to process only the autodiscovery network layer reachability information (NLRI) update messages for LDP-based Layer 2 VPN and VPLS update messages (BGP_L2VPN_AD_NLRI) (FEC 129). Specifically, the auto-discovery-only statement notifies the routing process (rpd) to expect autodiscovery-related NLRI messages so that information can be deciphered and used by LDP and VPLS. You can configure this statement at the global, group, and neighbor levels for BGP. The auto-discovery-only statement must be configured on all PE routers in the VPLS. If you configure route reflection, the auto-discovery-only statement is also required on P routers that act as the route reflector in supporting FEC 129-related updates.

  The signaling statement is not included in this example but is discussed here for completeness. The signaling statement allows the router to process only the BGP_L2VPN_NLRIs used for BGP-based Layer 2 VPNs (FEC 128).

  For interoperation scenarios in which a PE router must support both types of NLRI (FEC 128 and FEC 129), you can configure both the signaling statement and the auto-discovery-only statement. For example, a single PE router might need to process a combination of BGP-signaled virtual private wire service (VPWS) and LDP-signaled VPLS assisted by BGP autodiscovery. Configuring both the signaling statement and the auto-discovery-only statement together allows both types of signaling to run independently. The signaling statement is supported at the same hierarchy levels as the auto-discovery-only statement.

• cluster—Configuring a route reflector is optional for FEC 129 autodiscovered PE routers. In this example, the cluster statement configures Router RR to be a route reflector in the IBGP group. For inbound updates, BGP autodiscovery NLRI messages are accepted if the router is configured to be a route reflector or if the keep all statement is configured in the IBGP group.

• l2vpn-id—Specifies a globally unique Layer 2 VPN community identifier for the instance. This statement is configurable for routing instances of type vpls.

  You can configure the following formats for the community identifier:

  • Autonomous system (AS) number format—l2vpn-id:as-number:2-byte-number. For example: l2vpn-id:100:200. The AS number can be in the range from 1 through 65,535.

  • IPv4 format—l2vpn-id:ip-address:2-byte-number. For example: l2vpn-id:10.1.1.1:2.

• vrf-target—Defines the import and export route targets for the NLRI. You must either configure the vrf-target statement or the vrf-import and vrf-export statements to define the instance import and export policy or the import and export route targets for the NLRI. This example uses the vrf-target statement.

• route-distinguisher—Forms part of the BGP autodiscovery NLRI and distinguishes to which VPN or VPLS routing instance each route belongs. Each route distinguisher is a 6-byte value. You must configure a unique route distinguisher for each routing instance.

  You can configure the following formats for the route distinguisher:

  • AS number format—as-number:2-byte-number

  • IPv4 format—ip-address:2-byte-number

Two notable statements are included in this example. These statements are important for interoperability with other vendors’ equipment. The interoperability statements are not necessary for the topology that is used in this example, but they are included for completeness.

The interoperability statements are as follows:

• input-vlan-map pop—Removes an outer VLAN tag from the top of the VLAN tag stack.

• output-vlan-map push—Adds an outer VLAN tag in front of the existing VLAN tag.

Topology Diagram

Figure 1 shows the topology used in this example.

Figure 1: BGP Autodiscovery for LDP VPLS

• CLI Quick Configuration
• Router PE1
• Device CE1
• Router PE2
• Device CE2
• Router RR

To verify the operation, use the following commands:

• show route extensive

• show route advertising-protocol bgp neighbor

• show route receive-protocol bgp neighbor

• show route table bgp.l2vpn.0

• show route table vpls100.l2vpn.0

• show route table vpls200.l2vpn.0

• show vpls connections extensive

• show vpls mac-table detail

• show vpls statistics

AD in the routing table output indicates autodiscovery NLRI.