DSL System Options Grow Richer, Murkier

Posted: 05/15/1999

DSL System Options Grow Richer, Murkier
Flavors, Features, Carrier-Class Claims To Proliferate at SUPERCOMM '99 in Atlanta
By Peter Lambert

Digital subscriber line technologies are coming of age in mid-1999 with an emphasis on efficiency, flexibility and business user functionality.

Thanks to that maturity, carriers shopping for digital subscriber line (DSL) now may find themselves blessed and cursed with choices as they confront equipment options both more appealing and more bewildering. Highlights of DSL advances scheduled to be showcased at SUPERCOMM '99 include:

• Increased DSL access equipment port density yielding more DSL interfaces per central office (CO) rack at improving costs per port;
• Integration into single, multiservice boxes serving all forms of local-loop access;
• Equipment component redundancy, hot-swappability and other capabilities associated with large-scale, carrier-class operations requirements;
• A wider range of DSL flavors--including high-speed DSL 2 (xDSL-2) products designed to deliver two-way T1 (1.5 megabits per second [mbps]) capacity over one, rather than two, pairs of copper wires--enabling varied service speeds at varied distances appropriate to a range of market segments; and
• Increased support for business customer functionality, including customer premises routing, virtual private network (VPN) services, quality of service (QoS) controls and multiline voice over DSL (VoDSL).

As a prime example of the increasing complexity of DSL options, some of the early xDSL-2 product vendors claim more complete compliance with an incomplete standard than their competitors. Further, xDSL-2 vendors are implementing varied line code schemes, each claiming superior compliance with emerging spectral compatibility rules designed to prevent interservice interference.

Adding to the murkiness, the lines between consumer-oriented and business-oriented DSL show signs of blurring as vendors from both camps move up- and down-market to pursue small businesses and home office customers in the middle. Hawkers of asymmetrical DSL (ADSL) products originally associated with single consumer customers, for example, will pitch "symmetrical ADSL" at SUPERCOMM.

Further, modems and DSL access multiplexers (DSLAMs) no longer make an end-to-end system. Faced with the challenge of scaling DSL services such as VPN to tens of thousands of users per market, carriers also must shop for "services selection," or "broadband remote access services" (BRAS) platforms designed to terminate each user both physically and logically to a range of services and service providers in the public voice and Internet protocol (IP) network cores.

Still, if DSL equipment selection grows more nettled, it has begun to move out of the niche fringe into the carrier-class mainstream.

Carrier Class

Many SUPERCOMM exhibitors will emphasize higher-density DSLAMs and BRAS equipment. So, too, will they underscore integrated routing and service management functionality.

Startup AccessLan Communications Inc., San Jose, Calif., for example, will demonstrate a new Turbo SDSL 20-line card for its Packet Loop concentrator/router, featuring up to 960 ports at $500 per DSL port and the ability to forward thousands of IP connections at up to 250,000 packets per second (pps). AccessLan also will offer the ability to bond up to six DSL loops to deliver up to 9-megabit services in the underserved, "sweet-spot gap between T1 and (45mbps) T3," says Marketing Vice President Kumar Shah. "Then DSL carriers can begin to attach digital video, games and other high-end applications."

PairGain Technologies Inc., Tustin, Calif., will show its integrated access Avidia System, which it says now accommodates up to 18 channel cards for concentration of up to 144 xDSL-2 T1 ports into asynchronous transfer mode (ATM) virtual circuits (VCs). Similarly, Paradyne Corp., Largo, Fla., will unveil its 24-port HotWire Packet single-line DSL (SDSL) SDSL card capable of scaling to 432 ports per CO shelf, and ADTRAN Inc., Huntsville, Ala., will demonstrate its Total Access 3000 integrated access box with up to 28 xDSL-2 circuits in a 6-inch rack in a box that serves as a multiplexer for xDSL-1, integrated services digital network (ISDN) and fiber optic uplinks.

Building on its MAX remote access server (RAS) and Total Access Operating System, Ascend Communications Inc., Alameda, Calif., will demonstrate in its MAX TNT and MAX 20 platforms DSL concentration, routing, remote access dial-in user service (RADIUS) security and VPN management. "It can concentrate DSL loops then also route any number of IP sessions to multiple destination networks," says DSL Product Director Muthu Logan.

Similarly, the Cisco Systems Inc. 6400 Universal Access Concentrator now claims the ability to support 14,000 user-to-service provider IP connections, plus up to 3,500 simultaneous VPN connections and accounting features for service level agreements (SLAs) and wholesale DSL. "People have realized that DSL is another addition to your access toolkit, and all the networking learned in dial access is applicable," says Tim McShane, DSL business marketing director at the San Jose, Calif.-based company. "You must offer a full set of services, the ability to control the network and support service levels and high-touch IP services, as well as simple density and price."

The CopperEdge DSL multiplexer/concentrator from Copper Mountain Networks Inc., Palo Alto, Calif., featuring 768 SDSL ports, also offers per-flow routing and IP connection provisioning. "Existing routers can only terminate hundreds of end-to-end virtual circuits when you need tens of thousands," says Product Marketing Director Richard Shekar. "Our DSLAM can aggregate hundreds of users into one VC from central office to each ISP (Internet service provider), and the data rate of each VC can be throttled from the central office."

Redstone Communications Inc., Westford, Mass., soon to be integrated into Siemens AG's Unisphere Solutions Inc., Burlington, Mass., will unveil DSL software for its RX 1400 Edge Switch Router, which is designed to create 30,000 IP connections per physical interface and to apply its classification, queuing and scheduling processors to deliver service classes per IP flow.

Newbridge Networks Corp., Kanata, Ontario, also will demonstrate advanced service management, including VPNs and entertainment, for more than 1,000 ADSL or SDSL lines on its MainStreetXpress multiservice switch.

Business parks, campuses and multitenant unit (MTU) buildings also can benefit from advancing DSL chip integration by companies including ADTRAN; Alcatel Microelectronics Fab, Oudenaarde, Belgium; and Level One Communications Inc., Sacramento, Calif.

Ascend, for example, will unveil the MAX 20 DSL access concentrator designed to support from eight to 32 SDSL ports at 144 kilobits per second (kbps) to 768kbps, or 2.3mbps per port at a base price of $495 per port.

With that range of speeds on this low-end child of Ascend's 90- to 360-port DSL TNT, "the building manager can sell tiered services to his tenants," says Amra Tareen, line manager for Ascend's access switching products. The system precludes the need for new building wiring and for any external router or digital service unit (DSU). In the coming months, Ascend will add asymmetrical, plug-and-play G.Lite DSL to the MAX 20. Ascend projects 11 million MTUs overall could take advantage of broadband access in the long term.

Similarly, AccessLan will debut its $11,995 PL-1010 MTU DSL concentrator, with up to four T1-equivalent uplinks to carrier COs. Copper Mountain also will demonstrate its CopperEdge 150 DSL concentrator for the MTU market, available in 24- or 48-port configurations and selectable from 128kbps to 1.5mbps symmetrical speeds.

On the VoDSL front, Jetstream Communications Inc., Los Gatos, Calif., expects to formalize a program for making its high-density IP telephony gateway interoperable with multiple DSLAM and customer premises equipment (CPE) makers. Jetstream competitor CopperCom Inc., Santa Clara, Calif., will debut its CopperCom Gateway designed to support 44 T1 connections and 1,056 IP-to-circuit phone calls, while using GR-303 digital loop carrier (DLC) interfaces to extend Class 5 voice switch call-control features to IP-based VoDSL calls.

Flexibility Equals Reach

When carriers take into account the varied data rates, local-loop distances and spectral compatibility afforded by each flavor of SDSL, ADSL, xDSL and isochronous DSL (IDSL) technology, "you end up realizing that you need a variety of DSL services to deal with all conditions," says Frank Wiener, vice president of broadband DSL products for Paradyne.

Consequently, Paradyne will debut an SDSL product based on carrierless amplitude pulse (CAP) modulation to carry 1.5mbps service over 18,000 feet without generating spectral interference in adjacent voice services, while alternative 2B1Q modulation will be limited to 768kbps at less than 18,000 feet. Paradyne also will introduce a new ADSL intelligent service node with integrated routing, native address translation and other features associated with enterprise requirements.

Similarly, Nortel Networks, Richardson, Texas, will showcase its Universal Edge 9000, designed to accommodate multiple flavors of full-rate ADSL, G.Lite, xDSL, IDSL and Nortel's own 1 Meg Modem and 10-Mbps Etherloop access, as well as to support circuit and packet voice and VPNs.

The newest DSL flavor, single pair xDSL-2, will seek attention at SUPERCOMM as vendors including ADTRAN; PairGain; ADC Telecommunications Inc., Minneapolis; Fibex Systems Inc., Petaluma, Calif.; Metalink Ltd., Mountain View, Calif.; and Telco Systems Inc., Norwood, Mass.--a division of Atlanta-based World Access Inc.--debut early products.

And finally, CPE will proliferate at SUPERCOMM '99, with an emphasis on meeting business-customer requirements.

Efficient Networks Inc., Dallas, for example, will debut not only ADSL plug-and-play ease of use by consumers, but also full routing and bridging functions aimed at small businesses and branch office and home office users.

Fujitsu Network Communications Inc., Richardson, Texas, meanwhile, expects to announce a partnership with a large CPE maker, and it will demonstrate both ATM and frame relay-based end-to-end DSL.

Alcatel USA, Plano, Texas, which last month added Philadelphia-based Bell Atlantic Corp. to its long list of Bell company ADSL customers, will seek to widen its targets at SUPERCOMM, says Jay Fausch, senior access business development director. In addition to showcasing G.Lite, Alcatel will show its "Pro" and "Office" CPE lines and 768kbps symmetrical capabilities. "For competitive providers, we have not pitched our business-friendly symmetric capabilities," Fausch says. "We're also working voice over DSL, which will figure largely in CLEC (competitive local exchange carrier) decisions."

Deep Fiber Lives
FITL Lays Ground for FTTC
By Peter Lambert

BellSouth Corp. is doing it.

So are Bell Atlantic Corp. and US WEST Inc.

So is competitive provider McLeodUSA Inc.

Driven by high-speed data requirements, local-loop operating costs and, in some cases, entry into broadband video services, these carriers are taking fiber optic cable, rather than copper lines, deep into their last-mile networks.

In contrast to visions of three years ago, this construction is in most cases not yet fiber to the curb (FTTC) or fiber to the home (FTTH), but rather fiber in the loop (FITL), generally in new-build construction reaching nodes still hundreds or thousands of feet away from end customers. However, as lower-cost passive optical network (PON) technologies debut later this year, these carriers and their vendors believe that, in some service areas, FITL and broadband copper loop technologies such as digital subscriber line (DSL) could prove only a temporary step toward FTTC and FTTH.

"Some vendors have now achieved very high levels of integration in their designs, reducing the number of connection points and power consumption, and so the costs and early concerns about complexity are being minimized," says Dave Swanson, general manager of multimedia technology deployment for Atlanta-based BellSouth.

In areas where capacity needs and operational savings can be met by the combination of DSL and digital wireless cable, BellSouth will use them, Swanson says. In other areas--starting with Atlanta and Orlando--BellSouth says it is on schedule to pass 200,000 homes this year with FTTC, aided by equipment integration and by factory-spliced fiber that Swanson says cuts labor costs by one-quarter to one-third.

FITL, FTTC and PONs will be on the radar screen at SUPERCOMM '99 in Atlanta next month, as Plano, Texas-based Alcatel USA (Cedar Rapids, Iowa-based McLeodUSA's supplier); Cleveland-based RELTEC Corp. (BellSouth's supplier); Rohnert Park, Calif.-based NextLevel Communications Inc. and Herndon, Va.-based NEC Eluminant Technologies Inc. (both suppliers to Philadelphia-based Bell Atlantic and Denver-based US WEST); Murray Hill, N.J.-based Lucent Technologies Inc. (supplier to Tokyo-based Nippon Telegraph and Telephone Corp.); and other vendors display their wares.

NEC Eluminet, the digital loop carrier (DLC) FITL equipment of which is designed to extend fiber reach while also freeing up remote cabinet space for DSL equipment, anticipates that growing consumer demand for broadband will bring back the FTTC debate within a few years. Eluminet is developing PONs technology to extend FITL nodes affordably to the curb and home when that time comes, says Marketing Vice President Jim Holley.

Similarly, RELTEC will debut DSL cards for both its FITL and DLC equipment. "We see DSL from the central office as just a temporary step, because if you're going to deliver broadband to every home, you'll have to take fiber deep," says Mark McDonald, managing vice president of RELTEC 's access network product line.

"The closer we get to the home the more able we are to deliver full-service voice, digital data and multichannel video," says Bob Keating, senior manager for Alcatel's FITL and FTTC products. "Fiber to the economic point is what drives all this, and some people now are seeing that point at the curb."

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