Level 3 provides connections between Level 3 Gateway cities over the Level 3^® Network. In North America, on-net SONETS is available in 70 gateway locations. For more detail, please see Appendix A. The major cities are currently served in both Europe and CONUS. These cities are shown in Figure 3.7-1. Details of Level 3’s metro fiber rings provided in Appendix A. SONETS can be implemented on any Level 3 metro ring. In addition, new construction and purchasing of third-party dark fiber can be used to provide connectivity to government buildings at additional cost.

Using Level 3 Network assets and third-party CLEC and Local Exchange Carrier (LEC) network assets, Level 3 will provide SONETS access to the required Government locations. Level 3 manages more than 100 off-net service providers daily.

The Level 3^® SONETS is provided by using standard industry Add and Drop Multiplexer (ADM) and Wavelength Division Multiplexing (WDM) equipment with the appropriate interfaces (e.g., OC-3, OC-12). For long-distance connection, there is a dedicated long-haul ADM network employing four-fiber Bi-directional Line-switched Ring (BLSR) self-healing rings around Continental United States (CONUS). To reach the customer site, metropolitan (metro) area fiber rings are employed. Level 3 will deploy a metro ADM at the customer site with the appropriate interface card(s) to support the service(s). The metro ADM will be connected to the Level 3 facility using 1+1 protection, Unidirectional Path Switched Ring (UPSR) protection, or two-fiber BLSR protection, as appropriate for the demand of that Government site. The metro ADM is connected to the long-haul ADM if it is a long-distance circuit or to another metro ADM if it is a metro-area circuit. After equipment installation, the circuit is provisioned according to the Government order (e.g., as an OC 12 or OC-12c). The customer connection is either protected (four-fiber handoff) or unprotected (two-fiber handoff) according to the customer order.

The interfaces are supported through the commercially available interface cards installed in the ADMs at the customer site. Then, the circuits are provisioned according to the Government order (e.g., as an OC-12 or an OC 12c).

Network Topologies
Level 3 supports the required topologies and protection methods using commercially available ADMs and standard commercial practices. Ring topology is supported by using diverse fiber rings throughout the entire Level 3 Network. These are the standard, commonly used topologies implemented and operated daily by Level 3. Level 3 will not support the optional mesh topology.

Metro Point-to-Point: Metropolitan (Metro) SONETS provide a dedicated and fully route-diverse circuit between two or more Government-specified locations within one metropolitan market. Although the circuit will be configured to traverse the Level 3 Gateway, neither end of a metro point-to-point configuration terminates at the Level 3 Gateway.

Dedicated Metro Ring Service
Level 3 will support this optional service. Dedicated Metro Ring provides the Government with a dedicated optical metro ring service connecting two or more Government locations within a single metro market. Dedicated multi-node SONETS rings are custom-built to the locations specified by the Government and at the speeds specified by the Government.

Level 3 Intercity SONETS
The Level 3 intercity SONETS provide a fully route-diverse intercity circuit between two or more government-specified locations.

Protection Methods
The Level 3 Network is built using a ring architecture, and restoration is achieved through SONETS and SDH protection. The Level 3 long-haul network utilizes four-fiber BLSR, while Level 3 metro networks utilize two-fiber UPSR, 1+1, or two-fiber BLSR. The entire Level 3 Network is completely route-diverse and all protect capacity is non-preemptable.

Protection is supported through the ADMs and Distributed Communications Systems (DCSs) in the network. They can provide protected or unprotected handoffs, using 1+1 protection at the SONETS rates. The 1: N protection applies to electrical interfaces (DS-1, DS-3) and is supported by the DCS equipment.

For network protection, the equipment supports all required protocols except for Mesh. Mesh is not currently commercially viable and raises many operational issues that may cancel its cost-savings benefits.

The particular protocol used depends on the customer application. By employing protection on each ring separately (an end-to-end circuit may traverse multiple SONETS-protected rings), the end-to-end circuit availability is increased.

Unprotected Service: Level 3 has offered unprotected SONETS for years. Our unprotected Private Line service is offered at OC-3 and OC-12 rates. For OC-48 and OC-192 unprotected service, Level 3 provides wavelengths.

Alternatives

• OWS
• IPS
• EthS
• NBIP-VPNS

Restrictions

• None