IADs are the democratic revolutionaries of the new competitive telecommunications world. The small, low-cost "pizza boxes" that aggregate and transmit voice and data over the same access connection have brought integrated communications to the masses.
Almost as much as the CLECs who deploy them most avidly, IADs are children of the Telecommunications Act of 1996. Before IADs, small businesses would usually have one or more voice lines, or even a T1, which would be separate from a data connection, which in many instances was dial-up Internet service via a DS-0 or ISDN. Data and voice were completely different systems. IADs gave small and medium-sized businesses integrated access services for the first time.
IADs aggregate voice and data from a customer's premises and transport them to a CO via a single access line. On the customer premises' side, they generally have the ability to connect to PBXs and analog key systems, to digital voice systems and to routers. On the networks' side, most deployed units connect to single or multiple T1s, but ATM and DSL are changing the face of the business. There are a few devices that connect to SONET via an OC-3 port.
Dynamism
A watershed occurred in IADs at the beginning of 1999 as the first affordably-priced products appeared on the market that offered dynamic bandwidth allocation. Although the capability had been available for a couple of years, it wasn't until then that products hit price points that a wide range of CLECs considered attractive.
Before, IADs would integrate voice and data on a channelized basis. An IAD box for a 1.5mbps T1 might have 22 64kbps channels for voice and two for data. The channel assignments could not be changed without reconfiguring the box. This particular configuration was, and still is, widely deployed, such as a very early box from Vina Technologies Inc. (www.vina-tech.com).
Although inflexible, the TDM-based structure of the IADs had the advantage of being compatible with existing CO equipment, and no additional network elements were needed. The 64kbps DS-0s could be switched in the existing Class 5-based CO infrastructure.
However, the overall service was limited. "The big issue behind that is that it is all static," says Alan Ellison, vice president, network services, Actel Integrated Communications Inc. (www.actel.net). "Those working at 2 a.m. don't get the benefit of bandwidth no longer used by phones, so they can download large files or stream audio."
The big change that happened 12 months ago, along with lower prices, was the introduction of ATM for dynamic bandwidth allocation. This enabled products to support both voice and data without predetermining the levels of usage. If phone usage was low, as is often the case late at night, the bulk of the bandwidth could be used for data. One of the first to deploy ATM was Fibex Systems Inc., now a Cisco Systems Inc. (www.cisco.com) company.
Vina announced an ATM-based product in November 1998.
Besides maximizing bandwidth, ATM enables CLECs to offer service level agreements for the first time. ATM equipment measures performance for constantbitrate (CBR) and variable bit rate (VBR) traffic. Jim Diestel, general manager, market planning, Premisys Inc., now a Zhone Technologies Inc. (www.zhone.com) company, says, "Carriers want to deploy that kind of equipment so they can prove that, though a new company, they are worth taking these communications."
Now many IAD vendors offer such capabilities with ATM, such as Adtran Inc. (www.adtran.com), Anda Networks Inc. (www.andanetworks.com), Carrier Access Corp. (www.carrieraccess.com), Mariposa Technology (www.mariposa-atm.com), Telco Systems Inc. (www.telco.com) and Tellabs Inc. (www.tellabs.com).
"The significant appeal to us of dynamic bandwidth allocation is that we can give customers something that they haven't had before," Ellison says. "Also it's helpful from a marketing perspective, in that we can actually show customers that they are getting what they pay for as they demand it."
These products mostly use ATM over T1 lines to give dynamic bandwidth capability. In a typical IAD system, cards convert TDM voice to ATM. Voice cards, which usually come in increments of four or eight voice lines, use bandwidth only when phones are in use. At the CO, voice is converted back to DS-0s and sent to the Class 5 switch, while data traffic is sent to an ATM switch, usually to be routed to an ISP.
Products also include the ability to guarantee QoS for the voice channels, using a variety of schemes to prioritize voice packets over data packets in ATM or in IP over ATM. Most of the solutions are proprietary, though a few use IP QoS standards, such as differentiated services (DiffServ) and multiprotocol label switching (MPLS).
Besides providing great flexibility in bandwidth use, ATM also enables significant economies for bandwidths above T1. Until recently, if an enterprise needed more bandwidth than 1.5mbps, it had to jump to a DS-3 at 45mbps. The cost increment is significant: DS-3s cost upwards of $9,000 per month, compared to T1's approximately $1,000 price tag, and DS3 pricing is distance-sensitive.
With inverse multiplexing for ATM (IMA), a 3mbps ATM stream can be spread out over two T1s, by the IAD. Inverse multiplexing can be used across two to eight T1s. After that point, economics makes it more advantageous to make the jump up to a DS-3. At the CO, the T1s are combined again. Then the voice is separated from the data and forwarded to a Class 5 switch, while data is routed to an ATM switch.
Generation xDSL
Coming to market as the new year turns is the real excitement in IADs, DSL-based IADs, some including voice over DSL (VoDSL). The low cost of the DSL access lines themselves, combined with some aggressive price points from the early providers of DSL IADs, have made it the likely access technology of choice for the future. "We are facing a paradigm shift situation, which is great for the consumer," says Ellison.
The market launched in the last quarter of 1999, with just a few products coming to market from select companies. Best-known are three companies that made a big splash at SUPERCOMM 1999 with VoDSL equipment: CopperCom Inc. (www.coppercom.com), Jetstream Communications Inc. (www.jetstream.com) and TollBridge Technologies Inc. (www.tollbridgetech.com). They use ATM adaptation layer 2 (AAL2) with compression to statistically multiplex voice and make more efficient use of capacity. TollBridge's solution also includes a router for IP capabilities.
Accelerated Networks Inc. (www.acceleratednetworks.com), which is partly owned by Siemens AG (www.siemens.de), announced a VoDSL product in September 1999. Its products were also deployed by FirstWorld Communications Inc. (www.firstworld.com). Other DSL-based IAD systems are expected from leading IAD vendors in the first quarter of this year.
Like T1 systems, DSL-based IADs use ATM as their transport technology between the customer premises and the CO. The IAD in a customer premises is connected to a DSL line, which goes to a DSLAM at the service provider's CO or collocation site. The vendor's ATM equipment is behind the DSLAM and determines which packets go to a Class 5 switch and which to a data network. Equipment in the CO includes a GR-303 signaling interface, which enables the voice traffic to use the interface to the Class 5 switch more efficiently.
Most of the IAD equipment vendors are going to provide both DSL and T1-capable IADs. "The reason for that is that you have a certain base of customers that can be served only with T1, and now a base that you can serve with DSL," says Shahin Razavi, data product manager at KMC Telecom Inc. (www.kmctelecom.com), which uses a Vina product also OEM-ed to Lucent Technologies Inc. (www.lucent.com). "One vendor, one point of contact, and it makes life easier."
Because ATM is integrated into the DSL equipment with no need for a separate ATM edge device, the IADs are by and large much less costly than their T1-based counterparts. In addition, "many of the devices have a considerable amount of functionality of a traditional IP router built in," says Ellison.
So the value proposition is much stronger than in the past." DSL, he adds, allows CLECs to reach under-served markets--the customers that would have been too small for IADs in the past--with price points lower than T1 and comparable performance.
Service providers are unusually enthusiastic about the DSL equipment they are seeing, although Ellison notes one shortcoming: lack of variety of interface options on the premises side. "The limits I see are on the number of individual business lines we can offer from an IAD, such as POTS lines. We need more flexibility. It is more of a physical interface issue than the provisioning piece of it." Also integrated routing and firewall capabilities vary substantially from vendor to vendor. As first-generation products, however, the DSL units can be expected to mature in the future.
Ellison, who has tested equipment from all three and is evaluating product from Integral Access Inc. (www.integralaccess.com), says it is hard to determine at this point who is actually selling equipment. "When we ask who their customers are, they typically have just one to offer. But that's not taking away from the technology. It is just so new." The limiting factor for deployment of DSL right now is not the products, say service providers, but the ability of carriers to get their hands on copper local loops. "I would consider these products ready for prime time," says Ellison.
Deployments are at a very early stage, agrees Claude Romans, director for access networks for telecommunications research firm RHK Inc. (www.rhk.com), and it may be six months before deployment really begins to ramp up.
Nevertheless in the timely DSL IAD market, "Companies are aggressively moving ahead. It's the right idea at the right time."
Built-ins
The capabilities of the new generation of IADs go beyond simply reducing costs and increasing bandwidth.
For example, the flexibility of ATM opens other doors for CLECs, besides basic voice and data services, says Frederic Kunzi, chief technical officer for integrated services provider CTC Communications Inc. (www.ctcnet.com). "Our objective is to bring on board Class 4 and Class 5 switching capability. We can do that by extending virtual connections into the long distance carrier world," he says.
With the addition of an ATM gateway, voice traffic can be routed directly to a long distance carrier, giving the CLEC the ability to offer long distance services. CTC converts the voice from ATM packets to DS-0s to move them to the network of the former Frontier, which is now owned by Global Crossing Ltd. (www.globalcrossing.com). However, CTC is looking to a future when it can transfer calls as ATM packets and also take advantage of the statistical multiplexing of ATM.
Another advantage of IMA, Kunzi says, is the ability to use voice compression to maximize bandwidth use. Rather than use a full 64kbps for voice, service providers can use adaptive differential pulse-code modulation (ADPCM), a widely used audio-compression codec, to halve that bandwidth to 32kbps. Then, in a 3mbps channel, there is room for about 50 voice channels, 768kbps of frame relay and 768kbps of ATM. This enables companies to keep existing voice and frame relay services, and add a new service.
CTC went with a Layer 2 IAD solution from Accelerated Networks, so the company could offer basic connectivity and a clear point of demarcation with the customer premises, as well as the ability to provide services without asking customers to change their PBXs, key systems, routers and other equipment inside their offices.
Network operators are interested in the growing number of products that include an IP router, allowing IP over ATM. CTC plans to use IP to look beyond Layer 2 services. The company says it can use its current equipment with IP over ATM, taking advantage of IP's Layer 3 capabilities. "Today Layer 2 is very much traditional connectivity. We are in the packet-based connectivity business," says Kunzi. "Tomorrow in the IP world we can add value and give consumers bundled services."
Those services would range from e-mail and messaging to hosting, content management, managing firewalls and domain name server (DNS) functions and hosted applications, Kunzi says, all via the ATM-based IADs. "We have a lot of opportunity to help or manage intranets for our customers."
Razavi says KMC Telecom is looking at vendors, such as GVN Technologies Inc. (www.gvntech.com) and Adtran, for basic IP capabilities that allow the CLEC to do firewalls, DNS and dynamic hierarchical configuration protocol (DHCP), the server that assigns temporary IP addresses for sessions. He says vendors are building in such capacities because "they are realizing that the customer is looking for a single-box solution."
Another flexibility Accelerated Networks brought to CTC was the ability to move up to DSL-based IADs. "In our business the high costs are in the access," Kunzi says. "We were looking for a partner that could help us reach the point where we would have alternatives to reach the customer and optimize cost."
Wish List
At this point, few IADs from one vendor have interoperability with another vendor's CO equipment. In some ways, the issue is moot because the network segments where IAD systems operate, from the customer's premises to a CO, tend to be closed networks. Still, service providers would like to have some ability to mix and match products because no single manufacturer can meet all customer needs.
"We are hoping that more vendors will focus on standards," says Ellison. For example, he says, the number of POTS lines ranges from eight to 16 in IADs. It would be useful to be able to use the product that meets a customer's need, irrespective of the interface to CO equipment.
"I can see how operators would like interoperability, but I'm not sure anyone is going to help them," says Romans. In a market already very competitive, lack of interoperability is one of the ways vendors can hold on to customers, though a few have made partnerships with one or two other vendors with complementary products.
Accelerated Networks has an open interface for IP and QoS to which companies such as FlowPoint Corp. (www.flowpoint.com), now owned by Efficient Networks Inc. (www.efficient.com), can build customer premises equipment. CopperCom also opens the interface so other vendors can provide boxes at customer premise, to terminate the DSL line.
