| The advantage of the "optical" cross-connects is that they can reduce costs significantly in core networks. |
Optical network infrastructure at SUPERCOMM was all about size: bigger pipes, faster switches, more wavelengths, greater data capacities. Rather than merely increasing by a healthy percentage, the capacities of infrastructure equipment was increasing by factors of two, four and even 10.
In dense wavelength-division multiplexing (DWDM) equipment, the numbers of wavelengths on a single fiber were as high as 160, four times current products, and capacities of 240 are promised after the millennium. Cross-connects and switches for optical networks promise speeds of more than 2 terabits per second (tbps) in the next year, and hundreds of interfaces at the OC-48 (2.5 gigabits per second [gbps]) level. Even hoary synchronous optical network (SONET) equipment is now looking at speeds of OC-768 (40gbps).
Some would suggest that even with such strides in the capacity of the infrastructure, data networks are staying just one step ahead of the tidal wave of Internet packets that will descend on networks in the next decade. If so--and there is every indication that, with the growth of broadband access, that tidal wave is on the way--it will be a very good decade indeed for optical equipment vendors.
SUPERCOMM '99 was the coming-out party for a new generation of large-scale intelligent optical systems that operate strictly at the wavelength level. Although most were announced before SUPERCOMM, the convention was the first opportunity for many potential customers to kick the tires and look under the hood. From companies such as Monterey Networks Inc., Richardson, Texas; Sycamore Networks Inc., Chelmsford, Mass.; Tellium Optical Networking Systems, Oceanport, N.J.; and Corvis Corp., Columbia, Md., a new approach to optical network architectures emerged, with mesh-based systems such as router networks, and routes and restoration under control of intelligent network (IN) management systems. These systems are aimed strictly at the core of long-haul networks, with switching only at the wavelength level.
|
Today optical switching "would impact cost negatively because it is very expensive and not as reliable" as electrical switching.
--Nick DeVito, director of marketing and product management, Tellium Optical Networking Systems |
Although billed as "optical," these products mostly perform optical-to- electrical-to-optical (OEO) conversions to switch wavelengths, though the data streams are not demuxed. The advantage of the "optical" cross-connects is that they can reduce costs significantly in core networks. Because they leave pass-through traffic payloads untouched, they eliminate vast amounts of SONET demux/mux equipment and are highly efficient switching fabrics.
Certainly the most controversial optical product at SUPERCOMM was the Corvis Corp. CorWave, which the company claims is truly an all-optical network, but it refuses to identify the optical technology used in switching. The CorWave provides transport of 160 OC-48s (or 40 OC-192s) on a single fiber, and supports up to six fibers, with transmission distances up to 3,200 kilometers without electronic regeneration. It includes what the company calls "transparent" optical switching with a capacity up to 2.4tbps all on three racks of equipment.
Terry Unter, Corvis chief operating officer and vice president of manufacturing, says the elimination of the OEO conversions "provides an order of magnitude saving over OEO boxes." He says the Corvis system exploits that 70 percent of the traffic in a point of presence (POP) is transit-only. Also, an optical switch is not a real-time switch at the packet level, he says, and reconfigures only at the wavelength level. He says the company will "ship significant quantities in 1999," some in the third quarter, but declined to identify customers.
Tellium upped the ante on its "optical switches," as it terms its products, introducing the Aurora 512 to augment its existing Aurora 32. As its name suggests, the switch offers 512 optical connections, each operating at 2.5gbps (OC-48) for a total capacity of 1.28 terabits. Nick DeVito, director of marketing and product management, says the compact 512 takes up three standard bays and replaces 90 bays of SONET equipment. It will be available in about a year.
Tellium recently received a $250 million contract from interexchange carrier (IXC) Extant Inc., Aurora, Colo., for equipment to support national asynchronous transfer mode (ATM) services for competitive local exchange carriers (CLECs). DeVito says Tellium sees the optical cross-connect market as $20 billion to $25 billion over the next five to eight years.
Monterey Networks showed its 20000 Series Wavelength Router interconnected with the Cerent 454 by Cerent Corp., Petaluma, Calif., which aggregated and concentrated SONET traffic then fed it to the Monterey product for transport. Although Monterey is another company with a product that is not yet truly an optical switch, it is significant, says Michael Zadikian, founder and vice president of marketing, because it transports and switches at the wavelength level. Also, each wavelength router is part of an IN which the router elements communicate with each other and make dynamic routing decisions. Zadikian says the Monterey solution is attractive to larger network providers that need to control large data streams.
Also, he says, it is more attractive to a company selling a more uniform service, such as Omaha, Neb.-based Level 3 Communications Inc.'s Internet protocol (IP) network, rather than one selling finer-grained and leased services, such as Williams Communications Group, Tulsa, Okla. With a Level 3 "IP-only network, finally we get big enough pipes," Zadikian says. He says the cost of a Monterey router is in the range of "seven to eight figures."
Sycamore Networks, also a proponent of wavelength-based intelligent optical networking, introduced a network management system, Silvx, at SUPERCOMM. It can assess capacity across multiple rings--and eventually across a mesh network--and provision capacity. It sets up parameters to measure network performance and notifies of shortfalls. It also provides "metadata" tags on system software to identify which version of each software module is in use, a system that greatly simplifies upgrades.
Ciena Corp., Linthicum, Md., introduced its new architecture, LightWorks, for both long- and short-haul applications, which includes features for scalability, real-time provisioning, fast survivability and lower costs. A key product in that line is MultiWave CoreDirector, an intelligent optical core switch with bandwidth up to 640gbps. The switch matrix is 256-by-256 OC-48s, scaleable to 48tbps. Like other products in its class, it replaces multiple SONET optical add/drop multiplexers (ADMs) in a ring and allows traffic to be switched from one stacked ring to another, as well as services over multiple rings. Rick Dodd, director of product management, describes the CoreDirector as a "classic cross-connect with intelligence" that allows it to provision services, restore services and provide linear, ring and mesh protection.
As for the "issue" that most optical switches aren't really optical, most vendors insist it isn't an issue. Today, optical switching "would impact cost negatively because it is very expensive and not as reliable" as electrical switching, says Tellium's DeVito, "and the footprint is still big."
"It will be a progression," says Rod Alferness, chief technical officer of the Optical Networking Group, Lucent Technologies Inc., Murray Hill, N.J. True optical cross-connects for backbone applications could appear by 2001, he says, starting at about 256 ports and growing to more than 1,000. He says Lucent is not yet prepared to say which optical switching technologies it finds most promising, a position echoed by most optical networking vendors, who consider the question a key competitive issue.
More conventional offerings--but also of interest because they significantly increase the performance of traditional SONET architectures--included a number of new large "optical" cross-connects. They also use the term "optical" because all interfaces are optical, although switching is still accomplished inside the device at the electrical level. Most offer other features for managing high-volume networks.
Fujitsu Network Communications, Richardson, Texas, showed the Flash-192, a new SONET time-slot assignment/time-slot interchange (TSA/TSI) cross-connect with a 768 by 768 matrix, the largest available fully switched at STS1 (45 megabits per second [mbps]) granularity. It offers the ability to do integrated fiber rings, because it can produce OC-3s (155mbps), -12s (600mbps), and -48s (2.5gbps) from the same shelf, greatly decreasing the amount of equipment required. It also gives the ability to feed "subtending" rings, which are secondary rings split off from a main ring, at multiple speeds. The product also offers synchronous digital hierarchy (SDH, similar to SONET) signaling on all cards for applications outside the United States, an advantage in the long distance market. Combined with DWDM transmission, the Flash-192 gives the ability to support 32 10gbps lines or 320gbps in total.
Richardson, Texas based-Nortel Networks' new Optera Connect DX and HDX deliver a hierarchical solution to scale networks as volume increases. The DX provides 120gbps of total capacity, composed of eight 10gbps ports plus 16 2.5gbps ports, with the 2.5gbps inputs that can be configured as OC-3s, OC-12s or OC-48s. The matrix is 192 by 192 at the STS-1 level. The platform scales to a total throughput of 480gbps with a four-bay footprint. The HDX offers ports only at OC-48 and OC-192 (with the ability to move up to OC-768 in the future), and at total throughput that can scale to hundreds of 10gbps wavelengths in a DWDM system. The DX will go into trials in the fourth quarter of 1999 with general availability in the first quarter of 2000, while the HDX is slated to be available in the first quarter of 2001.
Alcatel Network Systems, Richardson, Texas, showed what it calls an optical gateway manager, the Optinex 1680, which combines digital cross-connect and ADM capabilities. It supports multiple inputs, from DS-3 through OC-768, and can manage wavelength-based services. The product has the ability to feed stacked rings, which normally require multiple network elements, yet it functions as one network element.
The 6500 cross-connect by Tellabs, Lisle, Ill., not only terminates SONET/SDH connections and provides cross-connects, but also acts as an IP/ATM switch. It will support any mixture of interfaces including DS-3/STS-1, OC-3/STM-1, OC-12/STM-4 and OC-48/STM-16. OC-192 interfaces will be available in the future. The total capacity is equivalent to 6144 DS3/STS-1 ports, or 320gbps, with support for expansion to 2.56tbps. A future release will manage ATM virtual circuits (VCs) and IP flows, using the same switching fabric, enabling operators to migrate from SONET/SDH management to ATM and IP management. The 6500 will be in trials in the fourth quarter of 1999 and available in the first quarter of 2000.
Hitachi Telecom (USA) Inc., Norcross, Ga., showed an optical routing and transport solution that links its AMN 6100 DWDM System with the Nexabit NX64000 Multi-Terabit Core Switch/Router via a 10gbps optical interface. The interface allows direct transport of IP and ATM data traffic at 10gbps between a transport system and a router without the use of an intermediate OEO conversion. The solution was to be in trials by the end of the second quarter of 1999.
Long-Haul DWDM
The agenda in long-haul DWDM products introduced at SUPERCOMM was simple: bigger capacities and longer spans. Spans of more than 500 kilometers with regenerators are common, and the increased exploitation of the so-called L-band (for long) of wavelengths of light, above 1,565 nanometers, has pushed the number of channels in systems to more than 160. The addition of channels in the S-band (for short), below 1,490 nanometers, will put the number of channels over the 200 mark.
| Vendors have agreed on a standard interface between rings of different vendors, so traffic can be ATM or circuit-switched end-to-end, even if across multiple vendors. |
Fujitsu showed its FlashWave 320G full-duplex DWDM system. The 32-channel system offers both OC-48 and OC-192 speeds in a 31-inch shelf. Over LEAF single-mode nonzero-dispersion-shifted fiber by Corning Inc., Corning, N.Y., Fujitsu demonstrated transmission for 600 kilometers without regeneration (six spans of 100 kilometers, each with a FlashWave in-line amplifier).
Fujitsu's long-haul DWDM system uses erbium-doped amplifiers with a 100-kilometer range. Fujitsu offers the option to use integrated transmitters, a money-saving strategy. Using transponders instead of integrated transmitters gives more flexibility and allows the use of multiple vendors in a DWDM system. However, for those who do not need that flexibility or multiple-vendor support, integrated transmitters are an economical alternative.
Alcatel showed a new addition to its Optinex 1640 line, a fixed, four-channel, in-line optical ADM that is very low cost because it is fixed. Alcatel plans to migrate the 1640 to 240 DWDM channels over the next two years. It has 40 now, and will have 80 by the fourth quarter, 160 by the third quarter of 2000 and 240 in 2001. Lucent is another that plans to exploit the L-band channels to add another 40 or so channels to its DWDM systems with its new WaveStar L-Band Amplifier. It has also shown a Bell Labs experimental system that transmits 40gbps per channel over 40 channels, for a total throughput of 1.6tbps.
Ciena pumped up its core long-haul product line with the MultiWave CoreStream, a follow-on product to its MultiWave Sentry, that can expand to 2tbps capacity.
NEC America Inc.'s Public Networks Group, Herndon, Va., added the SpectralWave Ring System to its SpectralWave line. The new product is a wavelength-based protection technology enabling carriers to deploy and protect high-speed data, such as IP and ATM traffic. It has interfaces for OC-48 only, designed to link directly to the IP routers and ATM switches of many different vendors. Available by the fourth quarter, the new product is designed to work with, but not replace, OC-3/12 infrastructure.
Fujitsu showed a spectrum analyzer that monitors the optical signal's power. The Fujitsu product monitors continuously and controls attenuators that change the signal strength. Fujitsu says it is the only vendor offering automatic power balancing, and that it has a number of patents for its monitoring system.
Bringing a low-cost solution to the question of replacement transmitters for DWDM, Fujitsu also showed a tunable laser. The initial product covers a range of eight channels, so it can replace any transmitter within an eight-channel range. Therefore, four different tunable lasers would be needed to provide backup for a 32-channel DWDM system. By 2000, Fujitsu plans to be able to offer a tunable laser that covers a range of 32 channels, so the same laser can be used to back up any channel in the system.
Lucent also showed its first tunable lasers, the WaveStar Tunable Laser, which it will introduce into its systems in the second quarter of 2000. The lasers will have a 20-channel range.
Fujitsu also offers a high-density OC-192 regenerator card that allows eight cards in a single shelf. The greater density will reduce cost in the system.
Still in the lab but announced at SUPERCOMM was technology for 170-channel DWDM by Fujitsu. Specifically, the company announced it had developed an amplifier for an additional 90 wavelengths above 1,580 nanometers. It also has developed a tunable laser for those wavelengths, which delivers a lower-cost way to provide back-up lasers or "spares."
Metro DWDM
Low-cost products that enable the use of DWDM in short-range (under 100 kilometers, so-called "metro") systems were a central feature of many companies' offerings at SUPERCOMM. There has been great pressure from customers to reduce the cost of DWDM for metro applications, and the first generation of equipment, most of which was composed of retooled long distance products, has had few sales.
Fujitsu's FlashWave Metro WDM line features a totally passive, 16-channel, two-way system the company describes as "very low cost." Its first customer is CLEC Allegiance Telecom Inc., Dallas.
Fujitsu has added a compact passive optical ADM that will drop up to four different wavelengths. The low-cost system does not offer a great deal of flexibility, says Jay Prichard, marketing manager, "but customers say this is what they want right now."
The Alcatel Optinex 1690 optical add/drop multiplexer (OADM) is a completely passive (no amplifiers) metro DWDM system with a range up to 40 kilometers, designed for short rings serving customers directly. The product, which is an OEM system from ADVA Optical Networking Inc., Ramsey, N.J., will have unidirectional rings, another cost saver. The reason, says Dana Hartgraves, director of product marketing and strategic business development, is that such systems tend to carry a lot of "homing" traffic--that is, traffic that comes from a large number of customers into a central point. The system is 16 channels now, but will migrate to 32 channels.
The company's 1686 is a "regional" metro DWDM system with a range of 40 to 150 kilometers designed to link smaller rings based on the company's 1690 product. Like the 1690, it has unidirectional rings because it also carries mostly homing traffic. "These are totally new products, not just tweaked long-haul products," Hartgraves says, adding it had been impossible to reduce prices sufficiently on the retooled long-haul products.
Tellabs debuted the Titan 6100, a 32-channel DWDM product for mesh and ring applications, as well as point-to-point. The product has been designed to eliminate transponders to reduce costs.
Osicom Technologies Inc., San Diego, has developed a new management system, LambdaGuard, for its GigaMux DWDM product line to provide optical-layer protection and management. LambdaGuard includes LambdaPath, an IP-based service channel on the fiber for use by management services. LambdaView is a probe that can sample all 32 channels of the GigaMux product optically to diagnose and adjust parameters such as power level, frequency and modulation. The product shows trends in the performance as well as failures. GigaMux product manager Don Buell describes LambdaGuard as "new and pricey," but says the company already has requests for field trials, which will begin in the fall. The product is unlikely to be used in campus or access applications, Buell says, but carriers will likely want to deploy it because "the more lambdas, the more it is worth it."
Ciena announced a sale to Cable & Wireless of its MultiWave Metro system to provide intracity connections in 20 metropolitan centers in the United States. The metro connections are part of a nationwide Internet network.
SONET
Fujitsu's Flash600 ADX ADM provides a range of multiservice options with support for IP interfaces (10Base-T and 100Base-T Ethernet), ATM (through DS3 OC-3 and OC-12) and traditional telephone (DS-1s, DS-3s, EC-1, OC-3 and OC-12), as well as SONET at OC-3, OC-12 and OC-48 rates.
A number of SONET equipment vendors are cooperating on a new interoperability standard, called Data-Aware Transport Activity (D.A.T.A.), for SONET and ATM transport. The SONET equipment and software are able to identify ATM cells, and the system is aware of the bandwidth requirements of data streams. It enables the establishment of flexible permanent VCs (PVCs) from 64kbps to the full bandwidth of the system (usually 150mbps or OC-3, or 600mbps or OC-12), solving the problem of inflexible bandwidths in SONET and inefficient use of bandwidth. One of the applications would be in transport of digital subscriber line (DSL) traffic from Internet service providers (ISPs) because of D.A.T.A.'s superior ability to handle bursts of traffic.
Vendors have agreed on a standard interface between rings of different vendors, so traffic can be ATM or circuit-switched end-to-end, even if across multiple vendors. "This is important to CLECs, because they are the ones pushing high-speed services," says Michael McLaughlin, vice president of Siemens Information and Communication Networks Inc., Boca Raton, Fla., "and they usually don't have an end-to-end network."
Cerent announced it has added Ethernet interface cards to its Cerent 454 SONET access and aggregation product. The new interfaces will enable gigabit Ethernet and packet switching over SONET, allowing service providers to switch and statistically multiplex Ethernet/IP traffic, and have that traffic operate seamlessly with the existing SONET infrastructure. Rob Kozlowsky, director, marketing, says the advantage of Cerent is that many service providers are already familiar with SONET, as opposed to other transport technologies, such as ATM. The products also are compact, with the ability to aggregate 192 DS-3s in three feet of rack space. Kozlowsky says Cerent will add ATM interfaces and later frame relay. The company also announced a $25 million contract from Williams for its Cerent 454 optical transport system, and that it has more than 70 customers, including CLECs, cable operators, utilities and incumbent carriers.
Hitachi Ltd., Tokyo, increased the top capacity of its SONET systems to OC-192 with the introduction of new 10gbps modules for its systems.
NEC Eluminant Technologies, the company's new optical fiber and access division, launched the Vista Intelligent Access Multiplexer, an economical line of OC-3/OC-12 multiplexers. Jim Holley, vice president of marketing, says the product was designed "in response to the lack of deployment of SONET in the access portion of the network." He says only 50 percent of the fiber in access is SONET because of cost and complexity. The new product also addresses some outstanding application problems by providing a mix of T1, low-speed optical and high-bit-rate DSL (HDSL) interfaces that had been lacking. He says the company also is investing in passive optical networking, a fiber-to-the-home technology with no active elements.
