September 2000

Looking For An Edge On The Edge
Beyond Bundling With VoDSL Integrated Access Devices

These providers anticipate that access to basic telephony and raw transport will eventually become commodities. They expect they'll need some way to further differentiate the services available to customers. They know that ultimately, they'll have to deploy highly customizable enhanced services, such as real-time Web-based user provisioning, unified messaging, follow-me services, call center applications, distance learning, and video conferencing.

The question, then, is how such services -- or, rather, applications -- should reach customers. Should the applications emerge from well within the service provider's cloud, from a feature server or a services node, or even an ASP? Or should the applications migrate, as far as possible, to the edge? From the service provider's point of view, the very edge would be the integrated access device (IAD), that is, equipment owned and maintained by the service provider, but residing on the customer's premises.

A relatively "dumb" IAD would be more than adequate for accessing applications within the service provider's cloud. A relatively "smart" IAD might offer enhanced functionality itself. The relatively smart equipment would be, potentially, more expensive -- at least the box itself, that is. However, it might also permit more economical use of network resources.

In the long term, intelligence will migrate to the edge. In the meantime, however, we'll likely see a variety of approaches, and a variety of IADs. Already, IADs are available in dizzying array.

With so many IADs available, the promise is that there should be IADs for any and every market segment. The concern, however, is whether these IADs will interoperate with other network elements. Standardization efforts are, as yet, immature. While standards gel, equipment providers are busy forging alliances and partnerships, developing certification programs, and staging their own interoperability tests. Thus, service providers may elect to move forward without delay, provided they are satisfied the necessary elements will work together, and yet allow for future growth, without locking them into a particular vendor's solutions.

The partnerships link together elements that reside downstream (the IADs), upstream (DSL access multiplexors), and yet further upstream (VoDSL gateways or next-gen switching platforms). The VoDSL gateways connect to Class 5 switches, typically via GR-303 or V5.2 interfaces. The next-gen switches, often described as Class 5 replacements, are packet-based platforms, and may be preferred in greenfield deployments, or by service providers interested in capping their investments in circuit-switched equipment.

VoDSL gateways offer several advantages. They leverage the value of existing circuit-switched equipment. Also, the service provider may deliver CLASS features while using the existing billing system. Next-gen switching systems, on the other hand, are an alternative to traditional TDM switches. The new platforms rely on IP, ATM, or IP-over ATM to transport voice traffic. In addition to providing CLASS features, they may work with external call control elements or call agents, which are sometimes called softswitches.

The providers of next-gen switching platforms hasten to cite the advantages of packet-based infrastructures for the creation of new services. So, it is possible to form the impression that there is a clear distinction between approaches described by providers of VoDSL gateways, and approaches described by providers of next-gen packet switches. However, it appears that technology abhors clear distinctions. Already, one VoDSL gateway vendor, CopperCom, has announced a strategy to enable a migration to a full packet telephone network. The strategy takes advantage of CopperCom's DTI acquisition, which accounts for the company's new CopperController. CopperCom intends to transform its packet-switched gateway and its CSX 2100 circuit switch into a full function media gateway controlled by the CopperController, communicating via the Megaco/H.248 standard protocol.

But whether a service provider deploys VoDSL gateways or packet-based Class 5 replacements, the interoperability challenge remains. VoDSL gateways typically work with IADs that support AAL2 signaling, while the packet switches typically work with IADs that support MGCP. Many IADs support (or will support) both standards.

In both types of deployment the DSLAM is of central importance, facing the IADs in one direction (the customer side), and the VoDSL gateway, IP router, or ATM switch in the other direction (trunk side). Located in the central office point of presence, the DSLAM delivers DSL services on copper loops to customer locations.

The DSLAM may offload Internet traffic directly to an ISP, conserving switch resources for voice traffic. Also, the DSLAM may support multiple DSL standards in a single chassis, typically through different line cards. These standards include SDSL, HDSL2, G.HSDSL, and ADSL-DMT.

And so, in brief, those are the basic elements in a VoDSL deployment: IADs, DSLAMs, and VoDSL gateways (interfaced with a Class 5 switch) or packet-based switches. In the remainder of this article, we will concentrate on the IADs, giving a variety of vendors an opportunity to clarify a selection of VoDSL issues, including interoperability, service quality, and the prospects for migrating intelligence to the edge (and delivering differentiated services).

Since we've emphasized interoperability, we've included comments from start-ups. However, we would be remiss if we did not mention, at least in passing, the solutions available from the largest vendors, that is, from Lucent, Nortel, and Cisco. Lucent, in addition to maintaining an interoperability program (the "Wired For DSL" program) for third-party certification, provides a range of equipment, including the CellPipe IAD, the Stinger DSLAM, and the PathStar Access Server. (Lucent partners with CopperCom, Tdsoft, and Jetstream for voice gateway functionality.)

Nortel's Succession architecture includes the Passport 4740 IAD, the Universal Edge 9000 multi-service access switch and the Passport 15000 CO cell switch. Finally, Cisco has entered the market through an aggressive series of acquisitions, including Fibex and TransMedia.

Do you foresee VoDSL solutions moving beyond cost-efficient bundling of basic services? What about quality issues (echo cancellation, effects of compression)? What about enabling the delivery of innovative enhanced services?

ADTRAN:
For VoDSL to flourish, service providers will have to think up creative methods for bundling advanced services. This is one key benefit to having a modular IAD that can grow and provide additional features based on customer demand. The IAD of choice will not only provide room to grow (both in terms of physical ports and features), it will be absolutely carrier class. Having a carrier-class IAD and a vendor with a proven track record for service and support will bode well for the service provider that chooses to deploy that particular product. In addition, the IAD will have to support remote management.

COPPER MOUNTAIN NETWORKS:
Initially, VoDSL will leverage its significant cost advantage to deliver basic bundled voice and data services. GR-303 platforms allow the reuse of existing CLASS and Centrex services like hunt groups and call transfer, and the softswitch platforms are readily customizable to tailor services and features for customer market segments, and even individual enterprises. As more service providers deploy this technology, they will diversify their offerings with value-added services such as real-time Web-based user provisioning, unified and universal messaging, follow-me services, call center applications, distance learning, and video conferencing.

Quality issues must be solved early on to ensure the delivery of toll-grade voice to subscribers, and to assure those subscribers that VoDSL is a robust and reliable alternative to traditional telephony. All the network components, including the IADs, DSL concentrators, switching elements, and voice gateways must take into account jitter, latency, toll-quality compression schemes, and echo in their design and implementation. Another issue, scalability, is dependent upon the delivery of carrier-class OSS, provisioning, and management systems to handle service turn-up, billing, customer service, and maintenance.

SEDONA NETWORKS:
Sedona believes that VoDSL solutions must move beyond simple bundling of basic services. The provision of "basic" CLASS features for voice is really "table stake" now, as is toll-quality voice. The next step, in our perspective, is the migration to provide complete end-to-end access solutions that facilitate delivery of customized bundled services. Starting with high-value services such as video-on-demand and unified messaging (which require tight voice and data integration), the solution must also address issues like network scalability, provisioning, as well as the ability to provide highly customizable services to satisfy needs of different segments of end users.

WOODWIND COMMUNICATIONS SYSTEMS:
VoDSL solutions, as they are being implemented today, are only the first steps toward providing value-added services. Basic voice and data services will quickly become commodity services. To attain customers which are now being served by a LEC, the successful new service provider will have to deliver even more services that are perceived as having higher quality, lower price, and more innovative and better customer care. The LEC will have to defend its customer base more aggressively by matching or surpassing the services, both in scope and quality, of the new, aggressive service providers.

The new service providers are already adding CLASS and calling features to basic voice services. Even though some service providers may enter the market with prices 20�30 percent lower than the ILECs, they are delivering these voice services as part of their product portfolio. Other service providers are entering the market with a bundle of managed services that they will deliver to the desktop. The more value added, the lower the churn and the higher the account control.

Echo cancellation, silence suppression, and compression are the expectation from service providers today. As the small business becomes more sophisticated, applications such as unified messaging and CTI will become more available for this market segment. As IADs attempt to span this broad range of network and customer requirements they must be more flexible and intelligent.

What sorts of IADs might prove most advantageous? Do some lend themselves to centralized service delivery? Do some lend themselves to distributed service delivery ("intelligent" IADs)? What about "PBX extender" or "remote PBX" functionality?

COPPER MOUNTAIN NETWORKS:
IAD functionality depends on the upstream gateway and VoDSL delivery technology. For GR-303 gateways, most if not all of the intelligence resides in the centralized Class 5 switch, so the IADs themselves may be relatively "unintelligent." For softswitch/media gateway combinations, the IADs must understand the signaling protocol of choice, most likely a form of MGCP. These IADs are intelligent and can "learn" new features under the direction of the softswitch server as a client in a distributed client-server VoDSL network. Intelligent IADs can also take part in call switching and routing decisions.

PBX extension is a valuable application for teleworkers, and also for enterprises that wish to exactly duplicate the corporate phone system at remote SOHO or branch office sites.

IADs are being developed for all market segments. They will be differentiated by 1) their voice functionality (whether they offer multiple port configurations -- 4, 8, 16, 24 analog ports -- or dsx-1 for digital PBX); and by 2) their data functionality (whether they offer features such as Frame Relay, VPN, and encryption and other security features).

EFFICIENT NETWORKS:
Efficient believes that an entire suite of next-gen IADs is required to serve the varying needs of residential, SOHO, and SMB customers. As carriers move "up" the customer continuum, the ability to decentralize the service points increases. For instance, a residential consumer offering may still lend itself to centralized services, via a Class 5 or softswitch architecture in the core. For enterprise solutions, call routing and management decisions can be pushed to the edge for local control and optimum network resource consumption in high call volume environments. The VoDSL architecture is highly flexible in this regard, allowing integrated communications providers to deploy an architecture today that can be scaled to meet the needs of varying service models in the near future.

VINA TECHNOLOGIES:
"Intelligent" IADs allow service providers to enter new markets quickly and accelerate services with minimal infrastructure investment. VINA defines an intelligent IAD as a device that is deployed in the customer environment (business customer) to serve all voice and data communication needs locally. These IADs provide Centrex services, local call routing, voice switching, data routing, and Internet firewalling. These are all built into the IAD and may be provisioned remotely.

"Basic" IADS (devices that do not incorporate any service intelligence) are better suited for established markets where the service provider has already invested in the necessary central office infrastructure to deliver centralized services. This type of IAD will slave to the centralized switch.

IADs that provide "bare bones" functionality will eventually be replaced by intelligent IADs that offer full feature voice functionality. VINA focuses on providing intelligent features in all of our product line.

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Several equipment providers offer SMBs CPE that combines broadband data connectivity (often via DSL) and phone system functionality, including auto-attendant, voice mail, and (in some cases) unified messaging.

BIZFON
Bizfon has concentrated on designing an affordable phone system that includes features that make sense for a small office. Thus, the Bizfon 680, a 6 inbound by 8 extension SOHO PBX/key system. Listing at $1,499, it features auto-attendant, voice mail, five-way digital conferencing, remote user access, and dial-by-name directory.

It is expandable up to a 24 x 32 system and it is designed to accommodate customers with little or no prior experience in configuring phone systems. A user can access instant human support via the Bizfon call center by dialing "299" from any extension. The 680 will automatically call Bizfon's 800 number and relay information about the customer and any previous call history. The 680 can be remotely configured by the call control agents via its dial-up modem and embedded Web browser.

FLEXION
The heart of the Flexion approach is the BusinessGuardian X300, an integrated communications platform that brings together the benefits of voice, data, and fax communications and business applications. The X300, a stand-alone hardware platform, works in conjunction with Microsoft Windows NT Server, Windows 2000 Server, and Exchange. The X300 currently support BRI, PRI T1, and broadband ATM T1 WAN connectivity; by the end of Q3 2000, the X300 support will support VoDSL (and data) in the form of G.SHDSL, a "superset" of HDSL2.

By harnessing the power of Windows NT Server, the X300 is able to deliver unified messaging, CTI, and other business applications, in addition to full PBX functionality.

MERLOT COMMUNICATIONS
The Merlot MAGNUM Applications and Services Platform (ASP) connects to VoDSL/VoATM circuits with an internal interface card that supports SDSL, HDSL2, VDSL, and T1. The MAGNUM is a one-box solution that offers a hybrid key system/PBX, 10/100 Mbps Ethernet switching, and a set of secure, WAN access capabilities.

The converged voice/data solution employs Merlot's Deterministic Ethernet technology to extend the single wire solution to the desktop, which Merlot asserts will deliver toll-quality voice over a single Ethernet link while preserving telephony quality and reliability. The system supports both digital and analog telephones, and its modular design allows business customers to configure a system to meet evolving communications needs.

PRAXON
The Phone Data eXchange is described by Praxon as a next-gen telephone system that goes beyond basic telephone functionality by integrating four essential business communications functions: voice, data networking, messaging, and Internet access capabilities. Designed for small and medium-sized businesses, the system supports ISDN, ATM, T1, and analog. A VoDSL release is slated for early next year. The product can scale from 8 lines to 32, and can support up to 64 extensions.

SONOMA SYSTEMS
The Integrator Xi and the xChange systems together offer broadband connectivity and intelligent telephony features. The Integrator Xi delivers analog and digital voice services, Internet access services, transparent LAN service, and Frame Relay services. It supports inverse multiplexing over ATM (IMA) over T1/E1 or HDSL2/G.SHDSL. Sonoma's IMA over HDSL2/G.SHDSL solution allows subscribers extensibility for DSL, supporting up to 6 Mbps of bandwidth over unconditioned copper.

The Integrator Xi delivers ATM traffic shaping and per-VC queuing deliver high performance services with QoS for service level agreements.

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