Creating Services-Oriented Building Area Networks

Pat Evans
06/01/2001

One of today's hottest acronyms in the telecom arena these days is MTU. MTUs, or multitenant units may be traditional tall, shiny buildings or campus-style office parks with groups of small buildings.

Many new service providers, including BLECs, CLECs and ICPs, are competing to address this market, alongside the ILECs, with varying degrees of success. Equipment providers have arrived on the scene to develop the ultimate MTU broadband solution. With approximately 70 percent of small and medium-sized businesses residing in multitenant office space, according to the Yankee Group (www.yankeegroup.com), the MTU market has evolved into a lucrative opportunity for delivering broadband communications services to the businesses and residents housed in these units.

As high-speed Internet access becomes a commodity and voice revenues continue to decline, providers must deploy advanced, converged broadband communications services. The service provider with the most cost-effective architecture that can be quickly and efficiently deployed will win this market battle.

Existing Solutions

Multiple architectures have evolved to create in-building broadband communications networks. These networks have been built using existing data networking and telecommunications equipment in various combinations. Although these solutions were not specifically designed for MTU applications, until now they have provided sufficient functionality to satisfy the basic voice and high-speed Internet access needs of the end user. However, in order to remain competitive, service providers must look to delivering advanced voice and multimedia applications. Existing solutions are unable to optimally deliver converged broadband services on a single network in MTU environments.

Digital Subscriber Line

DSL, primarily full rate asymmetric DSL (ADSL) and symmetric DSL (SDSL), is an attractive solution for delivering bandwidth within an MTU because it exploits the existing copper wiring within the building. However, DSL faces challenges that range from the consistency and stability of the existing wiring, to the legal access of using the wiring itself. It is often more cost-effective to install new riser systems to deliver broadband services, rather than attempting to use the existing building copper infrastructure that is owned by an incumbent carrier.

The DSL architecture includes a DSLAM, a WAN access device and an IAD or DSL modem. The DSLAM concentrates traffic within the MTU. The WAN access unit is typically a router with limited traffic management capabilities. An IAD is deployed for packet voice and high-speed Internet access; a simple DSL modem is deployed for high-speed Internet access only.

DSL solutions offer up to 8mbps per tenant, with a potential up to 26mbps symmetric, using very high-speed DSL (VDSL) solutions. In order to provide advanced data services, additional "boxes" are required; packet voice solutions are limited by the DSL solution. IAD-based packet voice solutions today are limited to a set of POTS lines (4, 8, 16 or 24). Additional voice services are deployed using a parallel in-building TDM network and equipment.

In order to provide DSL solutions, providers usually must acquire the IAD and DSLAM from two different vendors and perform system integration to ensure interoperability between the access and aggregation devices. QoS has not been thoroughly addressed by the IAD and DSLAM vendors, posing a serious provisioning problem for converged voice/data services.

DSL remains a very attractive architecture for delivering high-speed Internet access. However, its lack of robust voice offerings, as well as its lower bandwidth capacity and lack of a sufficient QoS, limits this solution to low-end commercial class C buildings or residential applications.

Ethernet Switches

Ethernet switches appear to be an obvious choice for delivering broadband to the MTU. Large switches with multiple 10/100 mbps ports, virtual local area network (VLAN) support or limited Layer 3 capabilities were designed to satisfy high-speed data networking needs. Simple data-only applications can be delivered via Ethernet drops directly to each tenant's office, eliminating the need for terminating devices at each end point. A WAN access device, such as a router, is needed for network access and a VoIP gateway is required for derived voice support.

The Ethernet switch architecture deployed today offers 10/100 mbps service to each tenant. However, Ethernet technology over copper is limited to 100 meters, which is not great enough to reach much of the multitenant office space. Since service providers are already building out new riser systems, they are beginning to install multimode and single-mode fiber optic cable in addition to the CAT 3/5 cable. In response to the Ethernet range limitation problem, Ethernet over fiber with future gigabit Ethernet capabilities is being deployed.

Similar to the DSL solution, the Ethernet switch solution is primarily a high-speed Internet access solution, solving the bandwidth issue to the tenant. With more fiber optic cable being installed in the risers and the opportunity for migration to gigabit Ethernet transport, bandwidth-intensive application delivery is possible for the foreseeable future.

However, advanced data services require additional "boxes", packet voice solutions are costly and limited, and a majority of voice services are still delivered using a parallel in-building TDM network, requiring additional boxes. The lack of VoIP availability and quality limit Ethernet switches as a complete MTU solution. As in the DSL approach, this solution requires the service provider to invest in system integration and increases the cost of operations for nonconverged voice and data networks.

Metro Optical Platforms

With high capacity network capability within the building and seemingly unlimited capacity available from the backbone network providers, the "last mile" bottleneck is becoming more of a "mid-mile" issue. Mid-mile or metro-fiber/metro access products are typically designed to sit on a metropolitan fiber optic ring and deliver multiple services including TDM, IP and ATM. These products have high bandwidth capabilities and are designed to bring broadband transport into high-density metropolitan areas.

According to Cahners In-Stat (www. in-stat.com), only 3 percent to 5 percent of all MTUs currently have fiber access into the building. Undoubtedly this will advance, but for now, deploying fiber optic connectivity into an MTU is a costly undertaking delaying deployment for awhile. Also, these platforms will continue to be surrounded by additional equipment in order to deliver consumable services to end users. Optical platforms are high-capacity access devices that do little toward breaking down the large access pipe into billable services for the service provider.

Finally, as in the Ethernet switch approach, optical access technologies do not support legacy voice services in a converged network. Existing voice traffic revenue can only be wholesaled, and packetized voice services will require expensive upgrades. In the meantime, the MTU will need to be managed with two separate, nonconverged broadband networks.

In-building network architectures continue to evolve in response to customer needs and market pressures, with a general direction toward a converged, simpler architecture and higher speeds.

The Solution

While many are attempting to deliver services or products for the MTU market, few have addressed the true network issues in the delivery of broadband inside the building. An MTU-centric broadband infrastructure is required to address the deficiencies of today's existing solutions. An MTU-centric architecture should have the following attributes to be optimized for the delivery of high performance broadband services to these shared tenant facilities:

Cost-effective deployment of equipment and services
Lowers the overall cost of operations
Enables the delivery of converged multimedia services
Platform for billable value-added services

A services-oriented building area network (SBAN) is specifically designed for the cost-effective delivery of converged basic and advanced broadband services within MTUs. Instead of many standalone boxes and multiple networks, an SBAN provides a top-to-bottom systems approach that is optimized for converged services.

By implementing an SBAN, service providers will be capable of delivering unprecedented services to their customers. In addition, by deploying broadband access equipment directly into the communications rooms of MTUs, the expense and complexity of collocation required for traditional broadband service delivery can effectively be bypassed, enabling the service providers to realize higher returns on investments, increased profitability and faster customer penetration.

Pat Evans is vice president of business development for Kenetec Inc. (www.kenetec.com) He can be reached at (203) 723-4242.

Comparison of MTU Broadband Solutions

The nonprofit Resilient Packet Ring Alliance (RPRA, www.RPRAlliance.com), which promotes the standardization of a new data-oriented, fiber optic ring technology, expects to formalize a standard next spring. RPR will optimize metro-and wide-area fiber networks for data traffic, combining the protection benefits of optical rings with the on-demand bandwidth benefits of Ethernet. Principal members of RPRA include Cisco Systems Inc. (www.cisco.com), Lantern Communications Inc. (www.lanterncom.com), Luminous Networks Inc. (www.lumnet.com) and Nortel Networks Ltd. (www.nortelnetworks.com).

Cisco Systems Inc. (www.cisco.com) expanded its widely deployed Multiprotocol Label Switching Traffic Engineering (MPLS TE) technology to support three new features: DiffServ-aware Traffic Engineering (DS-TE), Cisco AutoBandwidth allocator, and Fast Reroute (FRR). DS-TE enables service providers to offer highly available, high-throughput applications with strong QoS guarantees. DS-TE also allows service providers to perform constraint-based routing of traffic requiring bandwidth or improved delay or jitter characteristics, such as voice traffic, thus achieving the highest levels of QoS end-to-end for that traffic. This feature is ideal for building services such as virtual leased lines for voice toll-bypass applications. The new Cisco MPLS AutoBandwidth allocator automatically increases or decreases MPLS TE tunnel bandwidth based on measured traffic load. The Fast Reroute feature enables quick recovery in case of link failures, which prevents end-user applications from timing out and also prevents loss of data. MPLS traffic engineering with Fast Reroute decreases fail-over times competitive with SONET for link restoration.

FirstMile Technologies, a national on-site service provider, will purchase up to $30 million in network infrastructure and services from Nortel Networks Ltd. (www.nortelnetworks. com) over three years to build community intranets for master planned communities in Dallas, Denver, Indianapolis and Tampa, Fla.

A new four-wire counterpart to the HDSL2 (T1.418) standard, known as HDSL4, is being established to complement HDSL2 by extending reach to customer circuits that extend beyond the carrier serving area range. ADTRAN Inc. (www.adtran.com) is serving as editor for Issue 2 of that standard, which will define HDSL4.

Bird On A Wire Networks (www.birdonawire.com), a Canadian managed hosting service provider, selected NetScreen Technologies Inc. (www.netscreen.com) line of broadband Internet security appliances to offer its customers integrated detection system solutions combining firewall, VPN and traffic management functionality using a single dedicated-hardware platform.

The new ThruWAVE Wireless Broadband Router from Hybrid Networks Inc. (www.hybrid.com) is a single-carrier, multiple-modulation router that enables fixed broadband wireless service providers to increase their customer capacity and coverage by offering near-line-of-sight capabilities. It supports quadrature phase-shifting key (QPSK), 16 quadrature amplitude modulation (QAM) and 64 QAM modulation schemes and interleaving options that improve system capacity and enable service providers to increase their subscriber bases by 20 to 40 percent. The ThruWAVE router is the CPE portion of Hybrid's fixed broadband wireless system. The headend unit, located at the transmission site, uses a new downstream modulator card to manage the multiple modulation schemes and interleaving options. The complete system will be available this year.

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