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Example: Ethernet-Based Layer 2 Circuit Configuration

 
Figure 1: Ethernet-Based Layer 2 Circuit Topology Diagram
Ethernet-Based Layer 2 Circuit
Topology Diagram

In Figure 1, a Layer 2 circuit is established between routers PE1 and PE2 to deliver Layer 2 traffic between customer routers CE1 and CE2. A Layer 2 circuit VC connection is configured on the PE routers only. No special configuration is required on the CE routers, and the provider core P0 router only requires MPLS and LDP on the appropriate interfaces to enable labels to be shared between the PE routers.

On Router CE1, configure the Fast Ethernet interface to handle VLAN traffic. Be sure to use the same VLAN ID both here and on the Fast Ethernet interface of Router CE2.

Router CE1

On Router PE1, configure the Ethernet-based CE-facing interface with the CCC encapsulation type of your choice. If you use VLAN CCC, include the vlan-tagging statement at the [edit interfaces ethernet-interface-fpc/pic /port] hierarchy level. Also, include the encapsulation vlan-ccc statement at both the [edit interfaces ethernet-interface-fpc/pic/port] and [edit interfaces ethernet-interface-fpc /pic/port unit unit-number] hierarchy levels.

Establish your Layer 2 circuit with configuration of the l2circuit statement at the [edit protocols] hierarchy level. Remember to include in your Layer 2 circuit configuration the IP address of your remote PE neighbor (usually the loopback address of the neighbor), the interface connected to the CE router, and a virtual circuit identifier for this VC. Then, configure MPLS, LDP, and an IGP (such as OSPF) to enable signaling for your Layer 2 circuit.

Router PE1

On Router P0, configure LDP, MPLS, and OSPF on the interfaces connected to the PE routers. The core router provides the MPLS backbone needed to tunnel Layer 2 traffic from the ingress PR router to the egress PE router.

Router P0

On Router PE2, complete the Layer 2 circuit by configuring statements to match those previously set on Router PE1. Configure the Ethernet-based CE-facing interface with CCC encapsulation. Again, you must include the vlan-tagging statement at the [edit interfaces ethernet-interface-fpc/pic/port] hierarchy level when you use VLAN CCC. Also, include the encapsulation vlan-ccc statement at both the [edit interfaces ethernet-interface-fpc/pic/port] and [edit interfaces ethernet-interface-fpc/pic/port unit unit-number] hierarchy levels.

Establish your Layer 2 circuit with configuration of the l2circuit statement at the [edit protocols] hierarchy level. Remember to include in your Layer 2 circuit configuration the IP address of your remote PE neighbor (Router PE1), the virtual circuit identifier previously configured on Router PE1, and the interface connected to the CE router. Finally, configure MPLS, LDP, and OSPF to enable signaling for your Layer 2 circuit.

Router PE2

On Router CE2, configure the Fast Ethernet interface to handle VLAN traffic. Be sure to use the same VLAN ID on this interface as the one seen on the Fast Ethernet interface of Router CE1.

Router CE2

Verifying Your Work

To verify proper operation of Layer 2 circuits, use the following commands:

  • ping mpls l2circuit interfaceinterface-name

  • ping mpls l2circuit virtual-circuit virtual-circuit-id neighbor ip-address

  • show l2circuit connections

  • Options: [brief] | [down] | [extensive] | [history] | [instance] | [local-site] | [remote-site] |[status] | [summary] | [up] | [up-down]

  • show ldp database

In addition to displaying bindings for IP prefixes, the show ldp database command also displays the bindings for the Layer 2 FECs.

The following sections show the output of these commands used with the configuration example:

Router PE1 Status

user@PE1> show l2circuit connections

Router P0 Status

user@P0> show ldp database

Router PE2 Status

user@PE2> show l2circuit connections