April 2002

Is Cable Able? Can SMBs Access Commercial-Grade IP Services Over Cable?

BY DEV GUPTA

It has long been assumed that ribbons of fiber optic cables would be the conduits by which broadband access will be brought to the businesses of America. It is only a matter of time, the thinking goes, before the myriad challenges are surmounted and we find ourselves in a world where �glass rules.�

It hasn�t happened � and there are those who think it probably never will. Cost and technology issues are keeping fiber snuggly bottled up in the network�s core and out of access networks. It is only seen in the offices of businesses in the most densely packed service areas. Moreover, there is no compelling reason to think this is going to change anytime soon.

This doesn�t mean, however, that the nation will be left to suffer interminably, coaxing bits and bytes through today�s aging copper infrastructure. The savior will be the cable industry, which is finally in position to realize its dream of effectively provisioning services to businesses. Slowdowns in its residential business and the exigencies of multi-billion dollar acquisitions � Comcast�s purchase of AT&T Broadband is only the latest � makes this move into a vibrant new market a top agenda item.

Overall, the cable industry is well positioned to move into the business market. On the corporate front, the regionalization and consolidation of the past decade play well to the business market. On the infrastructure side, it has overhauled its metropolitan-area networks, which are equal or even superior to legacy-based incumbent local exchange carrier (ILEC) networks. Likewise, operators have effectively replaced their prehistoric tree-and-branch local access systems, and now offer high-quality broadband hybrid fiber-coaxial (HFC) local access networks. Some estimates say that 70 percent of the small and medium-sized businesses (SMBs) in the United States are on or near this upgraded cable plant.

CHASING THE DREAM
There is, of course, a tremendous amount of effort that goes into making a dream into a reality, and the cable industry�s dream of entering into the business market is no exception. The problem is that the last few hundred feet of a coaxial cable system �the oft-mentioned last mile � is wholly unsuited for the kind of throughput and security required to serve businesses.

Cable operators use spectrum up to 750 MHz and infrequently up to the 860 MHz-range. The problems with intermingling residential and business services in this spectrum are fairly obvious. There simply is not enough bandwidth to support bandwidth-intensive business operations. This is especially true in the upstream, where its asymmetric nature�it generally supports less than 40 MHz�simply doesn�t work for most business applications. Finally, interspersing mission-critical, time-sensitive business traffic with low security, best-effort residential applications is an unworkable solution from the management and security points of view, especially as residential services proliferate and become more difficult to manage.

ALTERNATIVES
Operators have three alternatives if they want to use their metropolitan-area networks (MANs) to serve businesses. They can use their systems as they are. They can create essentially new, fiber-intensive �last hundred foot� infrastructures. Or, they can find a solution that really does serve business needs � but without reinventing the wheel.

The first solution is really no solution at all. The customer base willing to run its business services over today�s infrastructure are bargain hunters, usually smaller businesses or home-based workers satisfied with small swatches of bandwidth supporting quasi-secure applications. Perhaps some larger companies would run non-mission-critical applications on this network as a way to reserve cheap redundancy in case of an emergency.

This approach will never amount to anything more than a boutique business. Note, however, that this is the �solution� being used today. Some estimates say that more than half of the enterprises willing to give cable telecom carriers a try are turned away by the operator simply because the infrastructure in place can�t support the service the customer wants.

Those opting to create an essentially new last mile infrastructure must choose between active and passive approaches. In both cases, they may not like what they see.

The active approach involves a mix of SONET and ATM. The problem is that only about 10 percent of the nation�s businesses are near enough to SONET/ATM MANs to make this an economically viable solution. Construction experts estimate the cost of laying fiber and installing the necessary electronic devices at about $50,000 per end point. Even if this number is somewhat high, you can be sure of one thing � it�s an expense that notoriously parsimonious cable operators are not going to undertake.

There is a good deal of hype surrounding passive optical networking. People sometimes make the assumption that the absence of active devices reduces expense. This assumption is indeed true � to a point. But in most cases, this approach entails the laying of fiber, which is the greatest cost point of any infrastructure build. A PON/SONET scheme can cost $15,000�$20,000 per end point, which is still beyond the range of most cable operators.

Even if some take this leap, the results may not thrill them. This technology is liable to latencies in the 10-millisecond range. This makes them unsuitable for emerging ultra-fast applications such as storage-area networks and dubious candidates, at best, to carry voice traffic. Furthermore, bandwidth is limited to about 10 Mbps. That sounds like a lot, but can be exhausted pretty quickly.

So, are cable operators doomed to the frustrating fate of having a wonderfully efficient and high-capacity network laying helplessly a stone�s throw from business customers willing to pay them handsomely?

A CONTRADICTORY SOLUTION?
The solution is to use the coaxial cable already in the ground to or very near most of the businesses in the United States. But doesn�t this pose a contradiction? Didn�t we just dismiss the coaxial cable into premises as unsuitable? The answer shows that there is no contradiction whatsoever.

As we have seen, operators� success will be limited if they attempt to intermingle services in the relatively small 860 MHz residential spectrum space. Luckily, coaxial cable has huge capacity above 860 MHz � something on the order of 5-10 GHz. This can be unlocked, just as WDM and DWDM unlocked the huge latent potential of fiber. The challenge is finding an economically viable way to break out this bandwidth from the starting point of today�s installed base.

Operators can exploit the spectrum above 860 MHz to deploy switched Ethernet over existing physical connections. They can cost-effectively utilize the higher-frequency spectrum by creating shorter runs and regenerating signals at shorter intervals. One way to make this previously unused spectrum productive is to divide the tree-and-branch coaxial network into a number of point-to-point coaxial segments interlinked by switching elements. Additional bandwidth beyond 860 MHz can therefore be effectively used for transmitting and receiving high data rate signals while maintaining acceptable signal characteristics.

Each coaxial segment can be viewed as a point-to-point link over which the new data channel operates. Data is received and relayed at each endpoint. Signaling is required only link-to-link, eliminating the need to synchronize with a central head-end control device and the corresponding end-to-end ranging operations typical of Data over Cable Service Interface Specification (DOCSIS) systems. The existing services below 860 MHz coexist on the same physical cable plant and continue to operate as before, without degradation or other disruption.

REALIZING THE POTENTIAL
While alternatives will continue to exist for small and medium businesses hoping to finally take advantage of broadband, one fact remains: The cable industry can be more than a bit player when it comes to serving this large and lucrative market. By utilizing advances in technology designed to squeeze all the available bandwidth out of the existing infrastructure, cable is finally in a position to realize its potential of effectively provisioning next-generation broadband services to businesses.

Dev Gupta is the founder, chief executive officer, and president of Narad Networks and the visionary behind Narad Networks� strategic direction and services platform. Narad Networks enables tomorrow�s broadband IP services over today�s existing cable infrastructure by creating True Broadband networks. For more information, please visit the company online at www.naradnetworks.com.

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