Posted: 10/1997
Getting Full Network Utilization From SONET Multiplexing Equipment
A New Onramp to the Information Highway
By John Shaunfield
At last, carriers can tap the full capabilities of their SONET/SDH networks, thanks to a new generation of SONET add/drop multiplexers (ADM). The new SONET multiplexers provide onramps or gateways to the information highway--those SONET/SDH networks that are universally operated by local exchange carriers (LECs). The new multiplexers remove foreseeable limits on the amount or types of traffic that can be carried on the information highway.
They also allow carriers and end users to successfully manage bandwidth and effectively streamline network operations. Carriers can now simultaneously control their costs and improve their service offerings. By deploying these multiplexers in their networks, carriers can better deliver the services that end users want. Better customer responsiveness is key as carriers struggle for market share in an increasingly competitive environment.
A Look Back
At the time, competitive LECs (CLECs) were not yet a major market force, and end users had few carriers from which to choose.
With such limited competition, incumbent LECS (ILECs) were not compelled to provide lower-speed service, such as DS-0 (64 Kbps) lines. Those who did not need the speed of a T1 or larger line had even fewer service options than customers with higher-capacity needs. At the time, customers did not expect carriers to directly provide lower-speed lines.
Someone who wanted a DS-0 line used one of two methods. The first option was to install channel banks, which break each T1 line into 24 DS-0 lines. The customer used the DS-0s as phone lines, four-wire circuits, RS-232 lines, low-speed data channels, or a combination. The second method was to install bridges and routers on both ends of a T1 network. While providing customers with needed DS-0 capacity, each method had serious disadvantages. End-user organizations paid for much higher-capacity lines than they needed and for costly channel banks, bridges, routers and other customer premises equipment (CPE).
These drawbacks are eliminated by the new generation of SONET multiplexers, whose underlying technology, ironically, is not new. The multiplexers simply tap the inherent capabilities of the SONET/SDH architecture. Moreover, muxes of this kind were not developed until CLECs entered the market, spawning both greater competition and more demanding, savvy customers. With a choice of more service options, customers realized they could demand more from their carriers.
Less Additional Hardware
The new muxes also eliminate the need for additional hardware by providing terminal and add/drop functions within the same shelf. It supports common telco interfaces that end customers want--in a single piece of equipment. The new multiplexers support interfaces such as voice, two- and four-wire, and low-speed data, including V.35 and RS-232. They also provide direct interfaces to local area network (LAN) protocols such as Ethernet and asynchronous transfer mode (ATM), as well as video surveillance and distribution. The best of the new multiplexers provide interfaces to multiple Ethernet ports. Again, this new breed performs these functions directly without requiring additional equipment. In turn, network operators can meet end users' needs without installing channel banks, bridges and routers, and in some cases, digital cross-connects.
More Simple Network Management
The new SONET multiplexers also help customers achieve bandwidth management. End-user organizations buy only the capacity they need.
The advantages of bandwidth management are particularly clear in video security and surveillance applications. Some of the new SONET multiplexers can support full-motion video over T1 or smaller circuits and provide the switching functions for video channels throughout the SONET network. The best of these determines the bandwidth required by the number of active monitors in a control center, and not by the number of cameras in the network. With this capability, video security and monitoring can be done from remote locations in a SONET network. A security company can offer expanded services to customers while charging affordable rates for the video circuits--as can ILECs and CLECs. These previously cost-prohibitive services can give the provider a temporary competitive advantage in the marketplace.
In addition to reducing the need for additional hardware, they solve another problem for carriers. Because terminal, ADM and other functions are incorporated directly into the multiplexer, the carrier no longer must manage these functions. Now, such functions are managed directly by the SONET network management system. By eliminating the problem of multiple-vendor support for a single function, the new multiplexer helps reduce the cost of maintenance, training and support.
A Booming Application
The recent experience of a rural county government in the southern United States illustrates both the importance of the new generation of multiplexer and the market potential for competitive county officials who wanted to network four buildings as they converted paper documents to CD-ROM. The ILEC that served them proposed connecting the buildings with three DS-3 lines at a cost of $6,000 per line a month over 10 years. County supervisors balked at the cost and looked for other bids; no CLECs then serviced the rural area. Instead, the county awarded the contract to a private network operator. For less than $100,000, the county bought an OC-3 network, equivalent to three DS-3s.
The county now will have its network paid for in a year, as compared to paying $18,000 a month for 10 years to lease DS-3 lines. The government also reduced long distance telephone charges because the network uses a single telephone system. Network management is so simplified that the county's information systems staff can handle the job. In addition, network management is streamlined because the multiplexer provides all the services that the county needs in a single piece of equipment.
For CLECs nationwide, these multiplexers open new markets and, at the same time, save money. Typically, a CLEC leases space from the manager of a customer-site building to install the CPE equipment necessary to meet the customer's telecommunications needs. Because the new generation of multiplexer consumes less power and utilizes only one shelf, the CLEC will be able to reduce its lease expense, because it requires less space. The CLEC, therefore, can reduce capital costs while still meeting end user needs.
The new generation of SONET multiplexers present many advantages with virtually no drawbacks. If carriers deploy multiplexers that take full advantage of the SONET/SDH's architecture, both the carrier and end user stand only to benefit.
The new breed of SONET/SDH multiplexer allows for such effective bandwidth management that customers pay only for the capacity they need. The advantages of bandwidth management are evident in video surveillance and security applications. As shown in Figure 2, the typical video network allocates bandwidth to the input signal. A network of 95 cameras and 20 monitors consumes 90 percent of the available bandwidth, leaving little room to expand the network or support other applications. By comparison, the new generation SONET multiplexer used in the same network consumes only 20 percent of available bandwidth, as shown in Figure 3. This efficiency is achieved because the new multiplexers assign bandwidth based on the output signal.
The new breed of SONET multiplexer holds particular promise for government services applications (See Figure 4). Municipal and county governments across the country are moving paper records to CD-ROM, requiring high-bandwidth networks. The new SONET mulitplexers perform key functions in such a network.
John Shaunfield, vice president of SonetLYNX architecture for Richardson, Texas-based Intelect Network Technologies, is responsible for the design, development and commercialization of fiber optics systems. For more information, call (972) 367-2100.
