A new generation of service-enabled IP networks

The current economic climate has forced service providers to take a long, hard look at the bottom line.  With reports of bankruptcies, revised revenue forecasts and ever increasing competition, service providers are keeping a watchful eye on any capital spending related to network expansion.  Coupled with a changing economic climate, advancements in optical networking technologies are significantly affecting how next generation networks are being built. 

Now that the core optical network is in place, the attention is on the services layer of the network, which will enable carriers to maximize their return on the invested capital in the optical transport layer with service-enabled IP networks. In many ways, the service provider industry today parallels the dynamics of another capital-intensive service business: the airline industry in the late 1970s.  

As competition increased and profit margins diminished, the airlines became acutely aware of the requirement to leverage their perishable assets–-airplanes--to maximize revenue, create demand for services and grow businesses profitably.  For service providers, perishable assets include bandwidth, servers, switches and routers that must be leveraged as a critical step toward sustained profitable growth. Just as the airlines offer and charge accordingly for different classes -- standby, coach, business and first class services -- service providers also offer four distinct classes of services today:

• High-speed Internet access that enables an enterprise to communicate with other users over the public Internet;
• Frame relay that accommodates bursts and provides low loss, moderate delay and jitter characteristics required to support data-oriented virtual private network applications' 
• ATM-enabled service that offers very low loss, low delay and bounded jitter characteristics required to support streaming traffic classes such as voice over IP (VoIP), video and storage area network (SAN) applications; and
• Private line services that support the isochronous nature of time division multiplexing (TDM) technology delivering premium loss, jitter and latency assurances.   

However, to maintain four distinct classes of service, four separate networks are required.  This approach is costly, resource intensive and basically impossible to maintain in a competitive world. It is an approach analogous to an airline having four different planes for each service class offered.   

...there are some very compelling reasons for service providers to create a single network that can meet the service needs of all applications, such as the evolution and dominance of IP and the need to maximize bandwidth and operational efficiencies to operate in the most profitable way possible.

These four types of services vary greatly in terms of user expectations for reliability, throughput, delay and jitter. For example, an Internet access network often delivers a low-quality, best effort service, while frame relay, ATM and private line networks have proven they are capable of meeting varied service level agreements (SLAs), depending upon the application.    

Given these different expectations, it is no surprise that service providers have traditionally built multiple networks to satisfy the needs of a differentiated customer base. However, there are some very compelling reasons to create a single network that can meet the service needs of all applications. IP-based networks meet this goal.   

The easiest way to determine the types of services that enterprise customers will demand from their IP networks is to simply review the types of services that are currently purchased today, which includes four types:  

• Pure Priority: Voice services over a private line represents a service that mimics the behavior of a TDM private line; namely fixed bandwidth, zero packet loss, fixed delay and negligible jitter. This type of service is also ideal for financial institutions that need completely predictable behavior for transferring their financial data records.

• Real-Time: Many large corporations today run videoconferencing over ISDN lines. Videoconferencing requires very low loss, bounded delay and bounded jitter. Other emerging services that require these attributes are VoIP, and (SAN) protocols over IP.

• Assured Delivery: This service level is typical of frame relay today, and is used for LAN-LAN connectivity, financial applications and SNA protocols. This service level requires variable bandwidth for accommodating bursts, low loss, moderate delay and jitter. Other emerging applications for this service level include extranets between buyers and their suppliers, and e-commerce applications. 

• Best effort: This represents a service without any significant SLA metrics. This is ideal for Internet access, which does not require any SLAs, particularly when traffic traverses multiple Internet service providers (ISPs).

Successfully architecting a service-enabled packet core is not a trivial matter. Traditional packet-based equipment was not built to satisfy the stringent requirements necessary to support a multiservice environment.  Technologies are now available that have incorporated the over-subscription capabilities of frame relay, along with the deterministic switching and class of service capabilities of ATM.  

What is required is a converged network architecture, using deterministic class of service enabled MPLS (multiprotocol label switching), which can deliver service levels that range from virtual private line to best effort.   As the volume of IP traffic dramatically increases, service providers need a packet-based platform that enables them to converge today’s service offerings onto a single IP-enabled network.  As service providers migrate current services to this IP-enabled infrastructure, they must be able to preserve the multiple service levels sold to end users.  

This move, in turn, enables them to capitalize on the emerging IP services marketplace.  Most importantly, this IP-enabled infrastructure will enable service providers to oversubscribe their network, maximizing network utilization while also preserving current services sold. Using packet-based technology at the core of this services layer gives service providers a huge opportunity to slash service deliver costs, while also differentiating their offerings in the face of intense competition.  

The inability to successfully implement verifiable classes of service in IP networks has been, up until now, a critical barrier to the realization of next generation networks. However, advances in silicon technology have opened up new frontiers for packet-based networking.  These breakthroughs, coupled with the valuable lessons learned from technologies such as ATM and frame relay, portend a very favorable environment for service providers that want to gain the benefits of operational efficiency and service flexibility inherent in packet-based networking. 

These new generation technologies will help service providers best use their assets by converging the service infrastructure, preserving classes of service in an over-subscribed network and readying them to delivery enhanced IP services.    
David Tolwinski is President and CEO of Tenor Networks, Acton, MA. He can be reached at david_tolwinski@tenornetworks.com.

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