Applications for Interconnecting a Layer 2 Circuit with a Layer 2 Circuit

MPLS-based Layer 2 services are growing in demand among enterprise and service providers. This creates new challenges for service providers who want to provide end-to-end value-added services. There are various reasons to stitch different Layer 2 services to one another and to Layer 3 services, for example, to expand the service offerings and to expand geographically. Junos OS has various features to address the needs of the service provider.

In Layer 2 circuits with structure-aware TDM Circuit Emulation Service over Packet-Switched Network (CESoPSN) encapsulation, you can configure the payload size for virtual circuits that terminate on Layer 2 interworking (iw) logical interfaces. The payload size must be specified to enable stitching of LDP-signaled TDM pseudowires in environments where an interconnection between two Layer 2 circuits is required. You can include the payload-size bytes statement at the [edit interfaces interface-name cesopsn-options] hierarchy level, to define the size in bytes (from 32 through 1024 bytes).

Interconnecting a Layer 2 circuit with a Layer 2 circuit includes the following benefits:

• Interconnecting a Layer 2 circuit with a Layer 2 circuit enables the sharing of a service provider's core network infrastructure between Layer 2 circuit services, reducing the cost of providing those services. A Layer 2 MPLS circuit enables service providers to create a Layer 2 circuit service over an existing IP and MPLS backbone.

• Service providers do not have to invest in separate Layer 2 equipment to provide Layer 2 circuit service. A service provider can configure a provider edge router to run any Layer 2 protocol. Customers who prefer to maintain control over most of the administration of their own networks want Layer 2 circuit connections with their service provider instead of a Layer 3 VPN connection.