white paper The Avidia Advantage Series Subtending: Reduce Equipment Cost and Complexity Executive Summary In today’s competitive telecommunications environment, you are faced with the challenge of minimizing the cost and complexity of equipment at the network edge. To meet this need, the ADC Avidia Integrated Access Switch (IAS) combines the functionality of an ATM edge switch with a DSLAM. Then, through subtending, in which several systems are viewed and managed by a single management platform, deployment of Avidia allows you to lower equipment and network management costs. Avidia concentrates multiple traffic streams to a single network uplink, enabling the elimination of expensive ATM edge switches. By reducing the number of network elements, you can reduce the number of element management systems, eliminating associated overhead costs such as training and staffing. Through subtending, you can lower the cost of delivering high-speed services to remote customers. This white paper explores subtending in more detail, by: • discussing two different configuration types (daisy-chain and star) • exploring both Central Office (CO) and remote cabinet deployment • showing the economic benefits that deployment of the ADC Avidia platform provides. Subtending Overview Avidia subtending allows multiple systems to be viewed and managed as if they were one system, through either a star or daisy-chain configuration. In either implementation, multiple systems connect to one system that aggregates the transmission of all the attached systems and provides one network uplink. The aggregating system is known as the subtending or source system and each of the systems connected to it are known as the subtended or destination systems. The figure below illustrates example star and daisy chain systems, and are just a few of the many configurations available through subtending. The subtending systems in each configuration aggregate the transmissions of the subtended systems and provide a network uplink through OC3 to the ATM Switch. Daisy Chain Configuration Star Configuration AV3000 AV8000 AV8000 DS1 ATM Switch Integrated Access Server Internet OC3 OC3 OC3 = Subscribers AV8000 12 PairGain PairGain AVIDIA3000 AV3000 AV3000 12 PairGain PairGain AVIDIA3000 AVIDA 2200 AV 54 1 AV 3 5 1 1 2 -A D S L C E L L 12 9 8 5 4 STATUS 1 PORT FAULT POWER AV 6 30 AV C C 3A 125V B A PG air ain PG air ain PG air ain Tx IN IN OUT MON OUT RED AIS LOS LPBK RAI MON LINEEQUIPMENT Rx SELECT T1 PORT ALARM ACT MAJOR MINOR ACO T1 CRAFT TEST LED POWER FAULT 8xT1 IMA-UNI 1 2 3 12 PairGain PairGain AVIDIA3000 DS1 DS1 DS1 AVIDA 2200 AV 54 1 AV 3 5 1 12 -A D S L C E L L 12 9 8 5 4 STATUS 1 PORT FAULT POWER AV 6 30 AV C C 3A 125V B A PG air ain PG air ain PG air ain Tx IN IN OUT MON OUT RED AIS LOS LPBK R AI MON LINEEQUIPMENT Rx SELECT T1 PORT ALARM ACT MAJOR MINOR ACO T1 CRAFT TEST LED POWER FAULT 8xT1 IMA-UNI 1 2 3 DS1 AV2200 AV2200 Subtending With Avidia Subtending can be set up using any of the four Avidia chassis: AV8000, AV6000, AV3000 and AV2200. AV8000, AV6000 and AV3000 systems can both subtend and be subtended while the AV2200 is typically a subtended only system. The two subtending configurations are explored in detail below. Subtending Through a Star Configuration In a star configuration, multiple subtended systems are attached directly to the subtending system that connects on the edge of the network. The subtending system aggregates the traffic from the subtended systems, switches all the traffic (its own and that of the subtended systems), and provides the network uplink. Each system, whether subtending or subtended, can connect to and manage subscriber traffic through modem connections. The following figure shows subtending within a star configuration. This example shows an OC3 interface as the network uplink for the entire subtended system. An AV8000 is the subtending system. Three chassis are subtended at three separate physical locations (sites). The subtending connection is through a DS1 link. Subtended AV2200 Subtended AV3000 ATM Switch Integrated Access Server Internet OC3 Site B Site C Site A = Subscribers DS1 DS1 12 PairGain PairGain AVIDIA3000 AVIDA 2200 AV 5 41 AV 35 1 1 2 -A D S L C E L L 12 9 8 5 4 STATUS 1 PORT FAULT POWER AV 6 3 0 AV C C 3A 125V B A PG air ain PG air ain PG air ain Tx IN IN OUT MON OUT RED AIS LOS LPBK RAI MON LINEEQUIPMENT Rx SELECT T1 PORT ALARM ACT MAJOR MINOR ACO T1 CRAFT TEST LED POWER FAULT 8xT1 IMA-UNI 1 2 3 Subtended AV3000 DS1 12 PairGain PairGain AVIDIA3000 Subtending AV8000 Subtending Through a Daisy-chain Configuration A daisy-chain is a serial link (or cascaded link) of up to three systems that has one network uplink connection and is viewed as one integrated system. The daisy-chain comprises: • one system functioning on the edge of the network to aggregate and switch ATM transmissions and provide the network uplink • up to two systems functioning as access devices. Each system, whether subtending or subtended, can connect to and manage subscriber traffic through modem connections. The relationship of subtending in a daisy-chain configuration is shown in the following figure. Two cards per system are needed to connect a daisy chain. Each chassis has one card connecting upstream towards the network, and a second card connecting downstream to a subtended chassis. This example shows an OC3 interface as the network uplink for the entire subtended system. An AV8000 is the subtending system. Two AV8000 chassis are subtended at two separate physical locations (sites). The subtending connection is through a DS3 link. When planning a daisy-chain system: • Plan an alternate or second path (such as a SONET ring) to re-route traffic in case of a failure of any link in the daisy chain. • Remember that there is a three system maximum with daisy chaining. • Consider the maximum distance allowed between systems based on transmission type. • Remember that you need to provision enough bandwidth upstream and downstream to maintain Quality of Service (QoS) and overbooking ratios. DS3 OC3 ATM Switch Integrated Access Server Internet AV8000 Subtended AV8000 Subtended AV8000 Network Uplink DS3 = Subscribers Benefits of Subtending Minimize the Expense of Central Office DSL Deployment As DSL networks are built out to Central Office co-locations, the access network must scale to accommodate subscriber growth. While single DSLAMs in each CO require only one network pipe for traffic backhaul, the demands on the network grow as new DSLAMs are added. In order to reduce the backhaul costs and traffic burdens on the core network over the WAN, you must concentrate uplinks from DSL traffic as close to the network edge as possible. Traditionally, this required an ATM edge switch to combine multiple T1s, DS3s, or OC3s into a single OC3 or DS3 pipe out to the network. This approach was used to minimize backhaul transport costs and reduce the burden on the overall WAN. An ATM edge switch takes advantage of QoS and traffic management to ensure network performance is not compromised. You may only deploy a single DSLAM in each CO when service is first turned up. However, business models generally anticipate multiple DSLAMs serving more subscribers as you achieve greater market penetration, as shown in the illustration below. DSLAM CO Colocation DSLAM DSLAM DSLAM Edge Switch ATM OC3 OC3 OC3 OC3 Core Switch OC3 Internet OC3 NOC OC12 BRAS By combining the functionality of an ATM edge switch with a DSLAM, Avidia effectively replaces the ATM edge switch and one DSLAM by performing both traffic concentration and multiplexing within a single chassis. As illustrated in the figure below, one Avidia system can subtend multiple systems, while still serving DSL customers as a DSLAM. This provides the same level of traffic concentration, statistical multiplexing, and traffic management as the ATM edge switch, while eliminating an extra network element. In the NOC, you can use ADC StarGazer EMS to manage all networked elements. By eliminating the ATM edge switch, subtending with Avidia can save you the cost of an entirely new piece of CO equipment, which can be as high as $50,000. In addition to equipment cost savings: • There is less equipment in the network to manage, and consequently fewer points of failure. • Network engineers do not have to provision an extra ATM switch in the co-location, reducing the cost of installation and network management over time. • Network managers have to learn fewer element management systems to provision and manage the subscriber network. • You will see reduced labor costs because of this increased operating efficiency. It is important to note that while many DSLAMs can provide subtending for similar traffic concentration, most can only do this in daisy-chain format where each system is subtended off the next. While you may choose to deploy DSL with this architecture, star-topology subtending, which is also supported by Avidia, is often preferable for traffic control and reliability reasons. AV8000 ATM OC3 OC3 Core Switch OC3 OC3 NOC OC12 BRAS Internet CO Colocation AV8000 AV8000 OC3 AV8000 Minimize the Expense of Remote Cabinet DSL Deployment The Avidia AV2200 chassis is an integrated ADSL DSLAM with POTS splitters, that has been designed for installation in remote Digital Loop Carrier (DLC) cabinets. When the AV2200 is used as part of the Avidia subtending solution, high-speed ADSL lines can be deployed to customers whose telephone lines are terminated in remote DLC cabinets. You can use anywhere from one to eight T1 lines to support the AV2200, depending on the oversubscription ratio and number of subscribers served by the system. This can increase your addressable market by as much as 50 percent. In the following example, an AV8000 in the CO subtends the AV2200s with the DS1 lines, while serving its own DSL subscribers out of the CO. ADSL + POTS Remote Cabinet POTS ADSL + POTS Avidia 2200 Remote Cabinet POTS ADSL + POTS CO NOC BRAS nxT1 nxT1 OC3 Avidia 2200 PSTN DLC DLC Internet ATM AVIDA2200 AV 5 41 AV 3 51 12 -A D S L C E L L 12 9 8 5 4 STATUS 1 PORT FAULT POWER AV 63 0 AV C C 3A 125V B A PG air ain PG air ain PG air ain Tx IN IN OUT MON OUT RED AIS LOS LPBK RAI MON LINEEQUIPMENT Rx SELECT T1 PORT ALARM ACT MAJOR MINOR ACO T1 CRAFT TEST LED POWER FAULT 8xT1 IMA-UNI 1 2 3 AVIDA2200 AV 54 1 AV 35 1 1 2 -A D S L C E L L 12 9 8 5 4 STATUS 1 PORT FAULT POWER AV 6 30 AV C C 3A 125V B A PG air ain PG air ain PG air ain Tx IN IN OUT MON OUT RED AIS LOS LPBK RAI MON LINEEQUIPMENT Rx SELECT T1 PORT ALARM ACT MAJOR MINOR ACO T1 CRAFT TEST LED POWER FAULT 8xT1 IMA-UNI 1 2 3 Avidia 8000 nxT1 nxT1 = Subscribers ISO9 00 1 ISO9 00 1 C E R T I F I E D C E R T I F I E D Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-946-3292 For a complete listing of ADC’s global sales office locations, please refer to our web site. ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. 100223PR 02/00 Original © 2001 ADC Telecommunications, Inc. All Rights Reserved An Equal Opportunity Employer This document is intended for planning purposes only. It therefore does not modify or supplement any ADC specifications, price quotes, or warranties relating to the products or services mentioned herein. Data quoted in this document are based on typical DSL performance. As such, this data cannot be considered applicable to any specific order or contract. ADC cannot assume responsibility for any consequences resulting from the use of this documentation. The information contained herein is subject to change at ADC’s discretion. Avidia and PairGain are registered trademarks of PairGain Technologies, Inc. ADC and the ADC logo are registered trademarks of ADC Telecommunications, Inc. No right, license, or interest to such trademarks is granted hereunder, and you agree that you shall assert no such right, license, or interest with respect to such trademarks. All other product names mentioned in this document are used for identification purposes only and may be trademarks or registered trademarks of their respective companies. The Power of Avidia DSL equipment that supports subtending offers a compelling value solution for today’s competitive telecommunications environment. Subtending with Avidia, supporting both daisy-chain and star configurations, gives you a financial and operational edge, allowing higher margins through reduced capital and operating expenses. With many versatile chassis sizes and a variety of network and subscriber side interfaces, ADC’s Avidia is the most powerful integrated DSL access switch available. Let us show you how the power of Avidia can work for you. Contact Information Matt Hemenez Product Marketing Manager, North America matthew_hemenez@adc.com Tel: 714.481.4686 or 800.370.9670 ext. 4686 Fax: 714.481.2111 Chris Sleath Product Marketing Director, International christopher_sleath@adc.com Tel: +1 972.680.7695 Fax: +1 972.680.0370 . white paper The Avidia Advantage Series Subtending: Reduce Equipment Cost and Complexity Executive Summary In today’s competitive. you are faced with the challenge of minimizing the cost and complexity of equipment at the network edge. To meet this need, the ADC Avidia Integrated Access