Service providers competing in this new era of converged voice and data services face a varied set of business and technical challenges as they seek to implement these services over their existing or green-field optical networks. The challenges are based not only on their service mix, but also on their installed service base, regulatory environment, and business history.

CLECs

Competitive local exchange carriers (CLECs) face many access challenges, especially in delivering direct access to unbundled local loops or bundled services to a multitenant dwelling. To meet these challenges, CLECs require the following:

• a cost-effective method of maximizing expensive carrier co-location space an efficient means of delivering multiple voice and data services on a cost-competitive basis
• a clear method of limiting capital expenditures on a point-of-presence (PoP) by PoP basis, thereby allowing the CLEC to expand its geographic footprint rapidly and cost effectively
• a simple means of provisioning and billing multiple voice and data services

ISPs

Internet service providers (ISPs), often delivering Internet access services in conjunction with a CLEC or incumbent local exchange carrier (ILEC), require fast and reliable interconnection of their IP/ATM and router-based networks to optical metro access networks. To deliver the next-generation, IP–based services that are critical to their success, ISPs require the following:

• an effective method of aggregating traffic from multiple metropolitan synchronous optical network (SONET)/synchronous digital hierarchy (SDH) rings
• an efficient method of linking SONET/SDH and IP/ATM network cores
• a cost-effective method of maximizing co-location space (where necessary)
• the ability to deliver next-generation access services without the requirement to replace existing network infrastructures

ILECs

Incumbent local exchange carriers (ILECs) face strong competitive pressure from all sides. Critical to their success is their ability to protect their established base of customers and services while developing and delivering the next-generation voice and data services their customers demand. To accomplish this transition successfully, they must find a means of optimizing existing infrastructures as they utilize them to deliver new, competitive service offerings. ILEC optical metro access requirements therefore include the following:

• a means of delivering next-generation voice and data services without disturbing existing SONET/SDH infrastructures
• a method of optimizing that SONET/SDH infrastructure for nonvoice traffic
• an efficient way of delivering combined voice and data services
• a simple means of provisioning and billing emerging voice and data services

To comprehend the complexities that today’s competitive service provider faces, consider the task of offering bundled voice and data services in a multitenant dwelling such as a high-rise, as shown in Figure 2.

Figure 2. Offering Bundled Services in a Multitenant Environment

Offering services in a multitenant environment requires not only a myriad of physical interfaces (such as T1/E1, T3/E3, Ethernet, optical carrier [OC]–x) but a diverse array of protocols (such as time division multiplexed [TDM], ATM, frame relay, xDSL, IP) as well. For example, to offer customers transparent local-area network (LAN) over Ethernet, the access device must be able to perform Layer-3 routing, including the support of routing protocols such as border gateway protocol (BGP), open shortest path first (OSPF), and routing information protocol (RIP). Another customer might have the need to concentrate digital signal (DS)–1s into a DS–3 for transport to a corporate headquarters; hence the access device must have the functionality of an M13. To access the service provider’s SONET ring, the device must also perform the functions of an add/drop multiplexer (ADM) and perhaps a digital cross-connect (DCS) switch. This resulting heterogeneous mix of traffic types, protocols, and multilayer processing calls for a very advanced architecture optimized for the metro edge.