DSL For Small Business: a White Paper

DSL For Small to Medium-Sized Businesses Leveraging Technology For Competitive Advantage

TABLE OF CONTENTS Abstract

2

Introduction

3

What is dsl?

4

HISTORY OF DSL

4

Benefits of dsl technology

5

Types of dsl

6

MAXIMUM SPEED / DISTANCE / KEY APPLICATIONS Dsl equipment

6 8

Security 10 Nortel networks dsl strategy

11

Nortel networks dsl solutions

11

SECURITY CONCERNS ADDRESSED

11

CUT COSTS - ELIMINATE LONG DISTANCE CHARGES

12

POLICY SWITCH IMPROVES NETWORK PERFORMANCE

12

Summary

12

Acknowledgement

13

Appendix a: glossary of terms

14

Appendix b: references

20

Appendix c: dsl resources on the internet

20

The following are all trademarks of Nortel Networks: Nortel Networks Logo; Business Policy Switch; BayStack. All other trademarks are the property of their respective owners.

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ABSTRACT Small to medium-sized businesses, along with home office workers and telecommuters, are being inundated with offers of high-speed Internet access – with options that include cable modems, T1 connections, ISDN and various types of DSL service. With all of the available choices, business owners and network managers must navigate a sometimes confusing sea of acronyms to find the service that best meets the needs of their organization.

Among the technologies listed above, DSL (Digital Subscriber Line)has emerged as a reliable and inexpensive vehicle that provides high-speed access, along with the convenience of an “always on” connection. DSL uses the existing copper wire infrastructure of the Public Switched Telephone Network (PSTN) to provide speeds comparable to T1 at a lower cost than a full-time ISDN connection.

DSL comes in many “flavors,” each with different maximum speed and distance limitations.

This paper will offer a look at the various forms of DSL technology, and will examine the ways in which DSL can help an organization cut costs and reduce overhead. We will also offer an overview of Nortel Networks’ DSL strategy and solutions, which are helping small to mediumsized companies leverage today’s technology for competitive advantage..

Compared to normal dial-up service, DSL is up to 70x faster over the same phone lines.

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INTRODUCTION The deregulation of the Telecommunications industry and the exponential growth in Internet usage have been the primary drivers of DSL technology, which for the first time has put highspeed Internet access within the reach of small and medium-size businesses.

Among the primary benefits of DSL technology is “always on� access to the company intranet or the Internet. Until now, a dedicated T1 connection has been the only viable alternative for companies seeking this type of access.

Another option for small and mid-sized businesses is ISDN, which offers higher speed than traditional modems (with transmission rates of up to 128 kbits per second). Many small and medium-sized businesses use a combination of ISDN and T1 for high-speed data transfer and Internet access. These technologies, however, are cost-prohibitive for many companies.

ISDN is billed on a cost per call and cost per minute basis in most areas, rendering it too costly for businesses that need an open access line. Organizations exploring the feasibility of a T1 connection must factor in the initial costs, which can be substantial; To begin using a T1 connection, some companies must first install a conditioned local loop and other equipment.

This additional expense, coupled with a sizeable monthly service charge, eliminates T1 as an option for many small and mid-sized companies.

Which brings us to DSL. The speed and cost-effective nature of DSL technology make it extremely attractive for telecommuters, small to mid-sized businesses, small office/home office (SOHO) workers, and companies with branch offices.

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WHAT IS DSL?

HISTORY OF DSL

DSL (Digital Subscriber Line) is a technology that brings high-

DSL was first envisioned as a way to deliver video on-demand in

bandwidth connectivity to homes and small businesses over

competition with cable television. While this application hasn’t yet

ordinary copper telephone lines. Connection speeds for DSL range

materialized, the demand for bandwidth generated by growing

from 1.544 Mbps to 512 Kbps downstream, (information sent from

Internet usage focused attention on the technology’s potential, which

host to client) and 128 Kbps upstream (client to host). DSL

led to the development of Internet access via DSL.

bypasses the voice network, placing a high-speed digital link on the copper telephone line and routing information directly to a packetswitching data network for efficient wide-area transmission.

The potential for high-speed Internet access via DSL was made possible by the passage of the Telecommunications Act of 1996, which introduced competition to local telecommunications. This

DSL “modems” use digital coding techniques to squeeze up to 99%

act required the Incumbent Local Exchange Carriers (ILECs) —

more capacity out of a copper telephone line without interfering

local telephone companies that control the local infrastructure —

with regular phone services, meaning you can talk on the phone or

to open up their services and network elements, making them

send a fax while accessing web pages on the Internet. Additionally,

available for resale by competitors. These companies are called

with a DSL connection the portion of the line used for data is

Competitive Local Exchange Carriers (CLECs) and they make DSL

continuously connected, providing “always on” access to the

available by installing equipment at the ILECs’ facilities, called the

Internet and company Intranet.

Central Office (CO). This equipment consolidates traffic from

DSL achieves higher data transfer rates than traditional modems or ISDN technology by utilizing more of the available bandwidth

individual DSL connections into backbone networks, connecting to Internet Service Providers (ISPs) or corporate networks.

spectrum. Ordinary telephone service only makes use of the 0 – 3400 Hz frequency range (which accounts for the 56 Kbps limit on standard analog modems). DSL, on the other hand, uses a much broader range of frequencies than the voice channel. This is done by outmoding the digital-to-analog conversion that modems perform and connecting both ends digitally. A DSL system does not use the analog-to-digital line card converters used for normal telephone lines; Instead, the carriers use special line cards that employ sophisticated digital signal-processing techniques to squeeze more capacity out of the line. As a result, more bandwidth is available, which in turn allows higher transfer rates.

DSL uses a broad range of frequencies to deliver higher transfer rates over ordinary phone lines.

Unused

Voice 5

BENEFITS OF DSL TECHNOLOGY DSL offers a host of benefits, ranging from increased productivity to

Lower cost per connection: Some businesses with hundreds of

reduced expenses. Following is a comprehensive look at some of

employees must pay for multiple T1 lines with monthly costs of up

these benefits:

to $1,500 per line. With DSL, businesses can use a router to share

Speed: First and foremost, DSL technology is about faster connection to the Internet and improved network-to-network communication.

Faster connection speed means less time spent waiting for e-mail

one DSL line and connect to dozens of workstations.

For

businesses that are already using ISDN or T1 services, switching to DSL can significantly lower expenses.

attachments or web pages to download; Files that take several

Lower installation cost: The fact that DSL uses the existing twisted

minutes to download with a 56K analog modem take only a few

pair infrastructure makes it less expensive to install than other

seconds with a DSL connection. To put that in perspective, imagine

services, which often require the laying of additional cable.

a company with 500 employees, each of whom now have an

Installing T1 service can cost upwards of $6,000, in addition to the

additional half-hour per day to devote to their assigned duties (time

monthly per-line charges. DSL typically costs under $1,000 to install,

that would have been spent waiting for a slow modem connection).

plus a minimal monthly fee.

That equates to two hundred-fifty additional man-hours per day in increased productivity – which translates directly to the bottom line.

Fixed cost for easy budgeting / expense control: Most service providers bill for ISDN service on a call-by-call, minute-by-minute

Connection is ‘always on’ : DSL does away with busy signals, which

basis, making it difficult for companies to track and control Internet

are becoming more common as Internet usage expands. It also

access expenses. With DSL, businesses typically pay a flat monthly

eliminates the need for users to log on when they need to send an e-

rate and the line is always open, saving money and simplifying

mail or download information from a Web site. This is especially

expense control.

important if a company is running its own mail or Web server. DSL also eliminates the possibility that remote employees or customers attempting to communicate with you will find a message reading “Host Not Available.” In addition to lost productivity, such a message often means a lost customer.

Performance on demand: Employees often download huge files such as e-mail messages with large attachments - or access Web sites with multiple graphics. If sufficient bandwidth is not available there are significant delays, which can lead to lost productivity. With DSL, files are downloaded much faster than with a traditional

Lower monthly cost: ISDN lines can be cost-effective if usage is

modem. And unlike cable modems, DSL is not a bus technology, so

kept to a minimum; The initial entry cost can be as low as $60 a

the bandwidth available to the end user is more consistent.

month, however costs go up as usage increases. T1 service costs between $900 and $1,500 a month, with varying installation costs (depending on the equipment that must be installed prior to the

Easy to manage: DSL allows you to focus your efforts on growing your company, rather than managing Internet access.

T1). DSL service, on the other hand, starts at around $40 per month

Online collaboration with vendors / partners / branch offices:

with no usage limit.

becomes much easier with the increased speed provided by DSL technology.

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TYPES OF DSL DSL is sometimes called xDSL, because there are several types, each with differing maximum speeds — ranging from twice as fast to 125 times as fast as a 56K analog modem.

Asymmetric DSL (ADSL) is best suited for applications patterned on a client server model. In such cases, most of the information is sent downstream from host to client. (The upstream channel can support less traffic.) Symmetric forms of DSL are more effective for business applications that require a symmetric or equal, bi-directional link.

Maximum Speed / Distance / Key Applications Below is a look at the various types of DSL, including maximum range and key applications.

ADSL (Asymmetric DSL) Delivers high-speed data and voice service over the same line.

Speeds are determined by the distance from the CO; as the distance increases, the speed available decreases.

Downstream Speed - 1.5 Mbps to 8 Mbps Upstream Speed - 64 Kbps to 800 Kbps Max. Distance From CO - 18,000 ft. (3.4 miles)* Key Applications - Small businesses and home applications, where downstream speeds are more important than upstream.

G.Lite ( pronounced “gee’-dot-light”) G.Lite is a variation on ADSL; DSL that the end user can install and configure. It is not yet fully plug and play, and has lower speeds than full-rate ADSL. Downstream Speed - 1.5 Mbps Upstream Speed - 384 Kbps Max. Distance From CO - 18,000 ft. (3.4 miles)* Key Applications - Consumer Internet access SDSL (Symmetric DSL) Downstream speed is the same as upstream. Does not support voice connections on the same line. Speeds are determined by the distance from the CO; as the distance increases, the speed available decreases.

Speeds - 160 Kbps to 2.3 Mbps Max. Distance From CO - 22,000 ft. (4.1 miles)* Key Applications - Business Internet access

* This is an approximate number; actual distance varies with setup.

IDSL (ISDN DSL) A hybrid of ISDN and DSL; it’s an always on alternative to dial up ISDN. Does not support voice connections on the same line.

Speed - 144 Kbps Max. Distance From CO - 35,000 ft. (6.6 miles)* Key Applications - As an alternate solution: it has a longer range than other DSLs, and is more affordable than dial-up ISDN. HDSL (High-bit-rate DSL) This is the DSL that is already widely used for T1 requires 4 wires instead of the standard single pair.

Speed - 1.54 Mbps Max. Distance From CO - 12,000 ft. (2.3 miles*; can be extended with signal repeaters) Key Applications - Used by ILECs for T1 service.

HDSL-2 is a new version that delivers the same speed as HDSL, using only a single wire pair.

VDSL (Very high-bit-rate DSL) Still in an experimental phase, this is the fastest DSL, but deliverable over short distance from the CO. Downstream Speed - 13 to 52 Mbps Upstream Speed - 16 Mbps upstream Max. Distance From CO - 4,000 ft. (three quarters of a mile)* Key Applications - Carry high-bandwidth over a short distance.

VoDSL (Voice Over DSL) An exciting technology that allows multiple phone lines to be transmitted over one phone wire, while still supporting data transmission.

Key Applications - Small businesses that can balance a need for several phone extensions against their Internet connectivity needs.

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DSL EQUIPMENT DSL technology requires certain equipment to be located at the customer’s premises, with other hardware located at the telco’s central office (CO).

Below is a breakdown of the items found at each end of a DSL connection.

DSLAM: (Digital Subscriber Line Access Multiplexer): • Located in the CO, DSLAMs consolidate traffic from individual DSL

Multiuser CPE includes: • LAN modems (or bridges)

connections into backbone networks connecting to ISPs or

• Routers. The routers typically have more features, and many

corporate networks. When a CLEC or an ILEC sets up a DSLAM in

include a built-in hub, enabling the user to acquire DSL and a local

a given CO, they make DSL available to the area served by that CO.

network at the same time. Routers without a built-in hub connect

CPE: (Customer Premises Equipment):

to a LAN through an external hub (or switch) with standard 10Base-T cabling.

• This is a generic term for the array of devices connecting the end

• Splitter: Used in ADSL installation, a splitter is a filter placed at both

user to DSL service. The CPE must be interopeable with the DSLAM,

ends of the local loop. It splits the line, separating the high-

so care must be taken to ensure compatibility.

frequency data communications from the low-frequency voice

Single User CPE includes:

communications.

• Microfilter: Also used in ADSL installations, the microfilter is

• Internal PCI card

placed on phone lines to filter out interference between the high

• USB modems

and low frequencies.

• Ethernet LAN modems (or bridges) (Most single-user options can be expanded to serve multiple users by adding proxy server software or Ethernet-to-Ethernet routers.)

DSL Modems • A DSL “modem” is a device that is placed at either end of the copper telephone line to allow a computer (or LAN) to be connected to the Internet through a DSL connection. Unlike a dialup connection, it typically does not require a dedicated phone line (a POTS splitter box enables the line to be shared simultaneously). Although DSL modems resemble conventional analog modems, they provide much higher throughput.

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THERE ARE FIVE BASIC DSL MODEMS: ATM to DSL Modem

Ethernet DSL Modem

• This option joins an internal ATM25 adapter with an external DSL

• Ethernet DSL modems attach to internal Ethernet cards when

modem for use with a residential PC, or a PC in a small office where

connecting single PCs, and to Ethernet hubs in multi-user DSL

access is not shared over a LAN. ATM signaling and encapsulation

applications that do not require full routing (such as the extension

occur within the PC; the ATM adapter connects to the DSL modem,

of central-site LAN services to a small remote office). Ethernet DSL

which buffers cell traffic to and from the DSL line. This equipment

modems encapsulate Ethernet frames into ATM for transmission,

combination provides end-to-end ATM, and is more common in

with no knowledge of a Layer 3 protocol such as IP.

Europe and Asia than in North America. It is used when ATM at the

• The Ethernet DSL modem offers immediate compatibility with

desktop is essential for quality of service and guaranteed

Ethernet-based networks, and for any non-IP traffic. Installation is

bandwidth, as in video-on-demand applications.

simple with little configuration required, though there is some

USB DSL Modem • A USB DSL modem is an ideal solution for any residential/consumer DSL application where the end user is responsible for installing the device. It is also the most practical DSL CPE for notebook users who telecommute or finish work at home in the evening.

• USB modems are extremely easy to install, and represent the only

complexity with external device management and software upgrades. Ethernet DSL modems can support only permanent virtual circuits (PVCs), offering no support for SVCs as other DSL access devices do. Operation requires flooding of packets across the DSL link under certain circumstances, using additional bandwidth.

DSL Router

DSL solution that does not require an internal card or NIC (ATM

• A DSL router is more fully featured than an Ethernet DSL modem,

signaling and encapsulation are performed in the PC). These

as it offers Layer 3 routing capabilities. DSL routers are the

devices are slightly more expensive than internal solutions, but add

preferred solution for multi-user LANs in remote offices, as they

value by minimizing customer support.

enable IP address management for each user’s desktop via DHCP-

PCI DSL Modem • PCI DSL modems offer the lowest equipment cost among DSL access solutions for home and small-office PCs. While initial setup requires the installation of an internal card, management is simplified by the use of existing operating system tools and GUI, with no external equipment to configure or manage. All ATM and DSL functions are performed in the PC.

Dynamic Host Configuration Protocol. DHCP allows network administrators to manage and automate the assignment of IP addresses in an organization’s network.

• The router can act as a packet filter or a firewall for enhanced security, and is highly compatible with Ethernet-based networks.

Installation is simple, with router and desktop connections made via Ethernet.

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SECURITY Despite the obvious advantages of DSL, any company that establishes an always-on Internet connection must address the security concerns stemming from the duration of the network connection DSL is inherently more secure than other broadband communications, namely cable modem service. DSL is a point-topoint connection between a consumer’s home or business and the telephone company switching office. Conversely, cable is a point-tomultipoint connection that shares network connectivity among homes in a neighborhood, much like a shared LAN. In addition, with DSL each customer has a separate “Private Virtual Circuit,” a unique connection that authenticates and secures the communication between the customer’s PC and the Internet.

For protected communication with others over the Internet, many companies use VPN (Virtual Private Network) hardware and software solutions that enable corporate users to establish secure tunnels between their homes and their corporate LANs — perfect for telecommuters. Similar to ISDN, the ease of deployment of the virtual mesh for DSL makes it attractive for VPN deployment - but with much higher data rates, more scalable growth, and lower overall costs by comparison.

Additional hardware and software should be added for increased security when a company maintains a continuous connection to the Internet: • Internet firewall: a system or group of systems that enforce a security policy between an organization’s network and the Internet. The firewall determines which inside services may be accessed from the outside, and which outsiders are permitted access to the inside services.

For a firewall to be effective, all traffic to and from the Internet must pass through the firewall for inspection; The firewall must permit only authorized traffic to pass, and the firewall itself must be immune to penetration.

It is important to note that an Internet firewall is not just a router, a bastion host or a combination of devices that provide security for the network; The firewall is part of an

• Firewalls can be physical devices or software agents that filter packets heading into or out of an organization based on a set of policy rules. Firewalls can allow access to a network by user name/password, type of service requested (ftp, http, etc.), location of destination (network or computer), or location of requestor (network address). A firewall can request authentication before allowing any traffic to pass at all, and in so doing can take advantage of the various authentication schemes available. There are two distinct types of firewalls – packet filtering and application / proxy; The difference between firewall types is primarily related to the way in which they handle external traffic.

• Packet-filtering firewalls control access and data into and out of the network. Packet-filtering firewalls can simply be routers or switches that are configured with access lists. They can permit or deny access based on the protocol, source or destination port, and source and destination of IP addresses.

For a higher level of security, packet-filtering firewalls can be configured to allow TCP communications only when initiated from the internal network.

• Application/proxy firewalls are devices or software agents that handle requests in place of the network application or server they are safeguarding. They provide network resources inside the firewall with a layer of protection, ensuring that secure resources are never accessed directly.

Application/proxy firewalls typically support local caching of Web content and address translation, thereby hiding internal IP addresses from Internet surfers. Proxy firewalls can allow access based on source address, destination address or an identity (authentication).

The key benefit provided by a firewall is IP address management (e.g., IP filtering), which provides a detailed level of control over inbound and outbound traffic on all interfaces. With IP filtering control on each interface, a network manager can specify exactly which traffic to allow or deny. Traffic can be controlled based on IP address, port value, various flags, and the protocol type of both source and destination IP addresses.

overall security policy that creates a perimeter defense designed to protect the network. Without a firewall, each host system on the private network is exposed to attacks from other hosts on the Internet.

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NORTEL NETWORKS DSL STRATEGY With our combined strength in voice and data, Nortel Networks is uniquely positioned to provide robust DSL solutions for small and medium-sized businesses. The objective of our strategy is to take full advantage of existing network capabilities, while providing a smooth transition to the network of the future. The goal is to deliver a turnkey system that combines high-speed Internet access, enhanced network-to-network communication and tighter security.

With over 100 years of experience, Nortel Networks has developed a keen understanding of telecommunications technology. Through our Meridian, Norstar and Centrex product lines, we have developed a superior group of products that have been designed to accommodate technological advances such as ISDN and DSL, and we continue to develop new and better products to meet the current and future needs of your business.

OS/2, Mac, Unix, and Novell clients. Instant Internet 100 will typically service an office of up to 20 clients, while the Instant Internet 400 product is recommended for offices with 20 to 100 users -- because of its high-speed (T1) capability with integrated CSU/DSU. With Instant Internet 400, multiple boxes can be connected to the network -- supporting additional users, load balancing, and fault tolerance. Both Instant Internet products offer complete firewall protection for the LAN and a comprehensive set of user access management tools, and have been revised to reflect the growing demand for DSL service. Product revisions in the NextGeneration Instant Internet include updated hardware design, and changes in product software structure and configurations as follows: • Integrated 7-port Layer-2 10/100 auto-sensing switch • Increased RAM and Flash memory • Increased processing power with Pentium Class 300 MHz • Additional WAN connectivity options

NORTEL NETWORKS DSL SOLUTIONS Nortel Networks is committed to helping small and medium sized companies build cost-effective, integrated voice and data networks that are scalable, reliable and predictable. Responding to the growing demand for DSL technology, we have developed a number of innovative products aimed at maximizing the benefits of DSL for small and medium-sized businesses, while minimizing the cost and complexity.

Our next-generation Instant Internet™ platform, which provides backwards functionality with all previous software releases, and our all-new SDSL Router, the Baystack 830, have been designed to facilitate high-speed Internet access with minimal capital outlay.

Instant Internet provides for secure connection of a company’s LAN / WAN to the Internet, and the Baystack 830 SDSL Router provides a DSL broadband solution for small and medium-sized businesses.

We have also introduced the Business Policy Switch, which allows a company to exercise greater control over bandwidth allocation, a growing concern as organizations become increasingly dependent on their networks.

Instant Internet Family Our Instant Internet 100 and Instant Internet 400 Internet Access Gateway products are complete solutions designed to connect an entire local area network (LAN) to the Internet through a single IP address. Instant Internet is completely adaptable to the LAN, working seamlessly with Windows 95, Windows NT, Windows 3.x,

• Dual and triple Ethernet versions from existing single Ethernet versions The next-generation Instant Internet 400 includes all of the above changes plus: • Triple Ethernet w/sync T1 including csu/dsu • Triple Ethernet w/sync V.35/X.21 w/analog • Triple Ethernet w/sync E1 w/analog • Triple Ethernet w/no internal modem • Triple Ethernet w/dual analog modem • Triple Ethernet w/ISDN, NA with NT1 • Triple Ethernet w/ISDN, no NT1 Next-generation Instant Internet 100 includes all of the above changes plus: • Dual Ethernet w/no internal modem • Triple Ethernet w/no internal modem • Dual Ethernet connector w/single analog • Dual Ethernet w/dual analog • Dual Ethernet w/ISDN, NA w/ NT1 • Dual Ethernet w/ISDN, no NT1 Beginning in October, 2000 the following revisions will be made to Instant Internet 400: • Triple Ethernet w/ADSL

• Triple Ethernet w/SDSL

• Triple Ethernet w/1-Meg Modem • Triple Ethernet w/cable Instant Internet 100, as of October 2000, will include: • Dual Ethernet w/ADSL

• Dual Ethernet w/SDSL

• Dual Ethernet w/1 Meg-Modem • Dual Ethernet w/cable 11

BACKWARDS FUNCTIONALITY Next Generation Instant Internet provides backwards functionality of all previous software releases: • LAN to Internet access for small to medium sized businesses, who need rock-solid security, comprehensive management tools, user logging functionality, and ease of use and installation • VPN capability with compatibility to Contivity* Extranet Switch 2.5+ to create secure IP-Sec tunneling between HQ and branch offices for the enterprise customer • VPN capability with secure IP-Sec tunneling between Instant Internet units to provide a more cost-effective small-medium sized business option.

• Enhanced WAN connectivity options (particularly SDSL and ADSL) to address the fast-growing market acceptance of this technology.

BayStack 830 SDSL Router The Baystack 830 SDSL Router is a simple to install general purpose router which acts as a stand-alone access device, providing broadband T1 speeds for your business at a fraction of the cost The router allows a company to connect to the Internet (w/possibility of future VPN) or establish a Virtual Private Network and provides enough bandwidth to support applications such as video streaming – all while avoiding the cost of a T1 line.

Hardware Configuration / Core Technologies • IP through the Internet • VPN: L2TP + DES encryption (IPSec in the future release) • IP/IPX routing and transparent bridging between remote offices through the Internet (over VPN) • DHCP and HTTP Security:

BENEFITS OF INSTANT INTERNET • Provides a DSL broadband, high speed internet solution for small and medium businesses together with the integrated capability to support VPN connection for companies with branch offices (Contivity) and branch-to-branch VPN (Instant Internet to Instant Internet) • Ability to deploy VPN technology - now or in the future (Extranet) • Faster technology that can affordably support multimedia networking in terms of transmission rates and networking equipment expense • Ability to connect more users to access corporate information from remote sites • Ability to run newer applications that require more bandwidth • Lower costs by replacing existing T1 with less expensive solution • Ideal for telecommuters who need higher speed access

• Private IP addresses not accessible from the Internet • DES encryption • IP/IPX packet filtering For small and mid-sized companies, the Baystack 830 SDSL Router offers a number of attractive features: • Faster technology that can affordably support multimedia networking in terms of transmission rates and networking equipment expense.

• The ability to connect more users to access corporate information from remote sites.

• The ability to run newer applications that require more bandwidth.

• Option of starting with 128K and increase speed as necessary – with no additional hardware costs.

• Graphical User Interface screens for easy access/management.

• Traditional Router Protocols (plus applicable voice and VPN support).

• Various Connection/Communications Line Options.

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POLICY SWITCH IMPROVES NETWORK PERFORMANCE With DSL technology, managing available bandwidth is critical to optimizing network performance while ensuring the availability of the network for mission-critical applications.

To address this need, Nortel Networks recently introduced the Business Policy Switch – a stackable switch capable of prioritizing business-critical voice and data traffic in an IP environment.

This infrastructure device allows a network manager to create a list of networking privileges covering issues such as who can use the network, when they are allowed to use it, and the specific applications they can run. The network manager can also establish security schemes and set bandwidth usage by user.

With the Business Policy Switch, network performance and reliability are increased by prioritizing traffic flow and enabling IP networks to handle the stringent latency requirements for high-quality voice transmissions. The Business Policy Switch integrates seamlessly with the Business Communications Manager to provide toll-quality IP telephony.

A scalable and stackable solution, the Business Policy Switch is compatible with BayStack switches and designed to help you meet the changing requirements of your business.

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SUMMARY DSL technology is expanding the availability of high-speed Internet access and network-tonetwork connectivity to small and medium-sized companies that had previously been unable to afford such services.

The technology is well positioned between inexpensive dial-up services and expensive T1 connections. The transmission speeds provided by DSL, along with its “always on� connection and lower price make it a viable data solution for any business. The speed and cost-effective nature of DSL technology make it ideal for telecommuters, small to mid-sized businesses, small office/home office (SOHO) workers, companies with branch offices, and consumers moving away from analog modems and ISDN.

DSL PROVIDES: Simultaneous Internet and voice/fax capabilities over a single telephone line Uninterrupted, high-speed Internet access that is always on-line Cost-effective solution for telecommuters and small businesses Data Security that exceeds other technologies

ACKNOWLEDGEMENT We wish to acknowledge the efforts of the DSL Forum, Universal ADSL Working Group, IETF, IEEE and others for their part in bringing DSL technology to the small and medium-sized business community. This paper has attempted to offer the reader a clear picture of DSL, along with ways in which it can benefit small to medium-sized businesses, however as technology is continually changing, information contained in this document may be subject to revision.

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APPENDIX A: GLOSSARY OF TERMS 100Base-T - A 100 Mbps LAN that maintains backward compatibility with 10 Base-T networks running at 10 Mbps.

10Base-T - A 10 Mbps Ethernet LAN that runs over twisted-pair wiring. This network interface was originally designed to run over ordinary twisted-pair (phone wiring) but is predominantly used with Category 3 or Category 5 cabling.

2-wire line - The set of two copper wires used to connect a telephone customer with a switching office, loosely wrapped around each other to minimize interference from other twisted pairs in the same bundle. Synonymous with twisted pair.

A Access Line - The physical telecommunications circuit connecting an end user location with the serving Central Office (CO) in a local network environment. See also Local Loop.

Access Network - That portion of a public-switched network that connects access nodes to individual subscribers.

Access Nodes - Points on the edge of the access network that concentrate individual access lines into a smaller number of feeder lines.

Access Rate - The transmission speed of the physical access circuit between the end user location and the local network. This is generally measured in bits per second; also called Access Speed.

Adapter Card - Circuit board or other hardware that provides the physical interface to a communications network; an electronics board installed in a computer which provides network communication capabilities to and from that computer; a card that connects the DTE to the network. Also called a Network Interface Card (NIC).

Asymmetric digital subscriber line (ADSL) - A group of DSL technologies that reserve more bandwidth in one direction than the other, which is advantageous for users that do not need equal bandwidth in both directions. See DSL. Always-on - Current dial-up services require the user to call the ISP. The connection is only active during the duration of the call.

Most DSL implementations (including ADSL, UADSL, and SDSL) enable the connection to be always on in a fashion similar to a LAN. Analog - An electrical signal or wave form in which the amplitude and/or frequency vary continuously, such as a voice signal over a Plain Old Telephone System (POTS) line.

American National Standards Institute (ANSI) - An official body within the United States delegated with the responsibility of defining standards.

ATM (Asynchronous Transfer Mode) - A high-bandwidth, low-delay, connection-oriented, packet-like switching and multiplexing technique. Usable capacity is segmented into 53-byte fixed-size cells; each cell is presented to the network on a start-stop basis, thus asynchronous. The key difference between ATM, X.25 packet switching, and Frame-Relay is that the packets of the earlier technologies varied in size. The consistent size of ATM allows video, voice, and data to be carried at a manageable rate.

ATM25 - ATM Forum-defined 25.6 Mbps cell-based user interface based on an IBM token ring network.

Available Bit Rate - Provides a guaranteed minimum capacity but allows data to be sent at higher capacities when the network is free.

Asynchronous - Occurring at different times. For example, electronic mail is asynchronous communication because it does not require the sender and receiver to be connected at the same time.

Asynchronous transfer mode (ATM) - A method of data transportation whereby fixed length packets are sent over a switched network. The ability to ensure reliable delivery of packets at a high rate makes it suitable for carrying voice, video, and data.

B Backbone - The part of a communications network that handles the major traffic using the highest-speed, and often longest, paths in the network.

Bandwidth - A measure of capacity of communications media.

Greater bandwidth allows communication of more information in a given period of time. Bandwidth is generally described either in terms of analog signals in units of Hertz (Hz), which describes the maximum number of cycles per second, or in terms of digital signals in units of bits per second.

Bit - A single unit of data, either a one or a zero, used in digital data communications. When discussing digital data a small “b” refers to bits, and a capital “B” refers to bytes.

Broadband - An adjective used to describe large-capacity networks that are able to carry several services at the same time, such as data, voice, and video.

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APPENDIX A: GLOSSARY OF TERMS Byte - A compilation of bits, seven bits in accordance with ASCII standards and eight bits in accordance with EBCDIC standards.

C Carrier - an electromagnetic wave or alternating current which is modulated to carry signals in radio, telephonic, or telegraphic transmission.

Central office (CO) - A telephone company facility that handles the switching of telephone calls on the public switched telephone network (PSTN) for a small regional area.

Central processing unit (CPU) - The “brains” of a computer, which uses a stored program to manipulate information.

Circuit-switched network - A type of network in which a continuous link is established between a source and a receiver. Circuit switching is used for voice and video to ensure that individual parts of a signal are received in the correct order by the destination site.

Competitive local exchange carrier (CLEC) - An American term for a telephone company that was created after the Telecommunications Act of 1996 made it legal for companies to compete with the ILECs. Contrast with ILEC. Customer premises equipment (CPE) - Any piece of equipment in a communication system that resides within the home or office.

Examples include modems, television set-top boxes, telephones and televisions.

D Dedicated connection - A communication link that operates constantly.

Dial-up connection - A data communication link that is established when the communication equipment dials a phone number and negotiates a connection with the equipment on the other end of the link.

Digital signal - A signal that takes on only two values, off or on, typically represented by “0” or “1.” Digital signals require less power but (typically) more bandwidth than analog, and copies of digital signals can be made exactly like the original.

Digital subscriber line (DSL) - A data communications technology that transmits information over the copper wires that make up the local loop of the public switched telephone network (See local loop).) It bypasses the circuit-switched lines that make up that network and yields much faster data transmission rates than analog modem technologies

Digital subscriber line access multiplexer (DSLAM) - A device found in telephone company central offices that takes a number of DSL subscriber lines and concentrates these onto a single ATM line.

Discrete multi-tone modulation (DMT) - A method of transmitting data on copper phone wires that divides the available frequency range into 256 sub-channels or tones, and which is used for some types of DSL. DNS - domain name service - The protocol used for assigning text addresses (such as www.nortelnetworks.com) for specific computers and computer accounts on the Internet.

E E-1 - A dedicated digital communication link provided by a European telephone company that offers 2.048 megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers Echo cancellation - The elimination of reflected signals (“echoes”) in a two-way transmission created by some types of telephone equipment, used in data transmission to improve the bandwidth of the line.

F Frame relay - A high-speed packet switching protocol used in wide area networks (WANs), often to connect local area networks (LANs) to each other, with a maximum bandwidth of 44.725 megabits per second.

Frequency - The number of oscillations in an alternating current that occur within one second, measured in Hertz (Hz).

Full-motion video - The projection of 20 or more frames (or still images) per second to give the eye the perception of movement. Broadcast video in the United States uses 30 frames per second, and most film technologies use 24 frames per second.

G G.dmt - A kind of asymmetric DSL technology, based on DMT modulation, that offers up to 8 megabits per second downstream bandwidth, 1.544 Megabits per second upstream bandwidth. “G.dmt” is actually a nickname for the standard officially known as ITU-T Recommendation G.992.1. (See International Telecommunications Union.)

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APPENDIX A: GLOSSARY OF TERMS G.lite [pronounced “G-dot-light”] - A kind of asymmetric DSL technology, based on DMT modulation, that offers up to 1.5 megabits per second downstream bandwidth, 384 Kilobits per second upstream, does not usually require a splitter and is easier to install than other types of DSL. “G.lite” is a nickname for the standard officially known as G.992.2. (See International Telecommunications Union.)

Gigabyte - 1,000,000,000 bytes, or 1,000 megabytes (see Byte).

Graphical user interface (GUI) - A computer operating system that is based upon icons and visual relationships rather than text.

Windows and the Macintosh computer use GUIs because they are more user friendly.

H Hertz - See frequency.

High bitrate digital subscriber line (HDSL) - A symmetric DSL technology that provides a maximum bandwidth of 1.5 megabits per second in each direction over two phone lines, or 2 Megabits per second over three phone lines.

Integrated services digital network (ISDN) - A circuit-switched communication network, closely associated with the public switched telephone network, that allows dial-up digital communication at speeds up to 128 kilobits per second.

Inter-exchange carrier (IXC) - A long-distance telephone carrier.

International Telecommunication Union (ITU) - A United Nations organization that coordinates use of the electromagnetic spectrum and creation of technical standards for telecommunication and radio communication equipment.

International Telecommunication Union/Telecommunication Standardization Sector (ITU-T) - The branch of the ITU that is responsible for telecommunication standardization.

Internet Engineering Task Force (IETF) - The standards organization that standardizes most Internet communication protocols, including Internet protocol (IP) and hypertext transfer protocol (HTTP).

Internet protocol (IP) - The standard signaling method used for all communication over the Internet

High bitrate digital subscriber line II (HDSL II) - A descendant of HDSL which offers the same performance over a single phone line.

Internet service provider (ISP) - An organization offering and providing Internet access to the public using computer servers connected directly to the Internet.

Hypertext - Documents or other information with embedded links that enable a reader to access tangential information at specific points in the text.

Intranet - A network serving a single organization or site that is modeled after the Internet, allowing users access to almost any information available on the network. Unlike the Internet, intranets are typically limited to one organization or one site, with little or no access to outside users.

Hypertext markup language (HTML) - The computer language used to create hypertext documents, allowing connections from one document or Internet page to numerous others. HTML is the primary language used to create pages on the World Wide Web. Hypertext transfer protocol (HTTP) - The first part of an address (URL) of a site on the Internet, signifying a document written in Hypertext Markup Language (HTML).

Hz - See frequency.

I Incumbent local exchange carrier (ILEC) - A large telephone company that has been providing local telephone service in the United States since the divestiture of the AT&T telephone monopoly in 1982.

Institute of Electrical and Electronics Engineers (IEEE) - A membership organization comprised of engineers, scientists and students that sets standards for computers and communications.

ISDN digital subscriber line (IDSL) - A type of DSL that uses ISDN transmission technology to deliver data at 128kbps into an IDSL “modem bank” connected to a router.

K Kilobit - One thousand bits (see bit).

Kilobyte - One thousand bytes (see byte).

L Last mile- See local loop.

Local area network (LAN) - A network connecting a number of computers to each other or to a central server so that the computers can share programs and files.

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APPENDIX A: GLOSSARY OF TERMS Local exchange carrier (LEC) - A local telephone company. LECs provide telephone service for phone calls originating and terminating within a single LATA. Local loop - The copper lines between a customer’s premises and a telephone company’s central office (See central office).

M Mb/s - Megabits per second.

Megabit - One million bits.

Megabyte - 1,000,000 bytes, or 1,000 kilobytes (see Byte).

Modem (MOdulator-DEModulator) - A device that converts digital data into analog signals and vice-versa for transmission over a telephone line.

Multicast - The transmission of information over the Internet to two or more users at the same time.

N Narrowband - A designation of bandwidth less than 56 kilobits per second.

Narrowband ISDN - same as ISDN. Network access provider (NAP) - Another name for a provider of networked telephone and associated services, usually in the U.S. Network service provider (NSP) - A high-level Internet provider that offers high-speed backbone services.

Network termination equipment (NTE) - The equipment at the ends of the communication path.

O Optical carrier 3 (OC-3) - A fiber optic line carrying 155 megabits per second; a U.S. designation generally recognized throughout the telecommunications community worldwide.

P Packet-switched network - A network that allows a message to be broken into small “packets” of data that are sent separately by a source to the destination. The packets may travel different paths and arrive at different times, with the destination sites reassembling them into the original message. Packet switching is used in most computer networks because it allows a very large amount of information to be transmitted through a limited bandwidth.

Peripheral - An external device that increases the capabilities of a communication system.

Plain old telephone service (POTS) - An acronym identifying the traditional function of a telephone network to allow voice communication between two people across a distance. In most contexts, POTS is synonymous with the public switched telephone network (PSTN).

Point of presence (POP) - The physical point of connection between a data network and a telephone network.

POTS splitter - A device that uses filters to separate voice from data signals when they are to be carried on the same phone line, required for several types of DSL service.

R Rate-adaptive digital subscriber line (RADSL) - A variation of DSL that uses carrierless amplitude phase modulation, divides the available frequencies into discrete sub-channels and also maximizes performance by adjusting the transmission to the quality of the phone line while in use.

Regional Bell Operating Company (RBOC) - One of the seven local telephone companies formed upon the divestiture of AT&T in 1984. The seven are: NYNEX, Bell Atlantic, BellSouth, Southwestern Bell, U S WEST, Ameritech, and Pacific Telesis.

Router - The central switching device in a packet-switched computer network that directs and controls the flow of data through the network.

S SDSL - Symmetric Digital Subscriber Line - This technology provides the same bandwidth in both directions, upstream and downstream. That means whether you’re uploading or downloading information, you have the same high-quality performance. SDSL provides transmission speeds within a T1/E1 range, of up to 1.5 Mbps at a maximum range of 12,000 - 18,000 feet from a central office, over a single-pair copper wire. This option is ideal for small and medium sized businesses that have an equal need to download and upload data over the Internet.

T T-1 - A dedicated digital communication link provided by a telephone company that offers 1.544 megabits per second of bandwidth, commonly used for carrying traffic to and from private business networks and Internet service providers.

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APPENDIX A: GLOSSARY OF TERMS Telecommuting - The practice of using telecommunication technologies to facilitate work at a site away from the traditional office location and environment. teleconference Interactive, electronic communication among three or more people at two or more sites. Includes audio-only, audio and graphics, and video-conferencing.

Universal Serial Bus (USB) - A computer interface with a maximum bandwidth of 1.5 Megabytes per second used for connecting computer peripherals such as printers, keyboards and scanners.

Time division multiplexing (TDM) - A digital data transmission method that takes signals from multiple sources, divides them into pieces which are then placed periodically into time slots, transmits them down a single path and reassembles the time slots back into multiple signals on the remote end of the transmission.

V

Transmission control protocol/Internet protocol (TCP/IP) - A method of packet-switched data transmission used on the Internet. The protocol specifies the manner in which a signal is divided into parts, as well as the manner in which “address” information is added to each packet to ensure that it reaches its destination and can be reassembled into the original message.

Twisted pair - The set of two copper wires used to connect a telephone customer with a switching office, loosely wrapped around each other to minimize interference from other twisted pairs in the same bundle. Synonymous with 2-wire line.

U Uniform Resource Locator (URL) - A text-based address used to identify specific resources on the Internet, such as web pages.

URLs are arranged in a hierarchical form that specifies the name of the server on which a resource is located and the name of the file on that server.

Universal ADSL Working Group (UAWG) - An organization composed of leading personal computer industry, networking and telecommunications companies with the goal of creating an interoperable, consumer-friendly ADSL standard titled the G.992.2 standard, and commonly referred to as the G.lite standard.

Universal service provider (USP) - A company that sells access to phone, data, and entertainment services and networks.

Variable bit rate (VBR) - A data transmission that can be represented by an irregular grouping of bits or cell payloads followed by unused bits or cell payloads.

VDSL - See very high bitrate digital subscriber line. very high bitrate digital subscriber line (VDSL) - An asymmetric DSL that delivers from 13 to 52 megabits per second downstream bandwidth and 1.5 to 2.3 megabits per second upstream.

Video on demand (VOD) - A pay-per-view television service in which a viewer can order a program from a menu and have it delivered instantly to the television set, typi-cally with the ability to pause, rewind, etc.

W WAN (Wide area network) - A network that interconnects geographically-distributed computers or LANs.

X X.25 data protocol - A packet switching standard developed in the mid-1970s for transmission of data over twisted pair copper wire. xDSL – Generic term that covers all “flavors” of DSL (e.g., ADSL, VoDSL, etc.)

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APPENDIX B: REFERENCES IETF RFC 1483 “Multiprotocol Encapsulation over ATM Adaptation LAyer 5.”

IETF RFC 1483 (see above) and IETF RFC 1577/2255, “Classical IP and ARP over ATM” IETF RFC 2364: “PPP over AAL5.”

IETF RFC 2516, “PPP over Ethernet.”

The International Computer Security Association (http://www.icsa.net) The Computer Emergency Response Team (http://www.cert.org) System Administration, Networking and Security (http://www.sans.org) DSL Forum (http://www.dslforum.org/security_index.html)

APPENDIX C: DSL RESOURCES ON THE INTERNET The ADSL Forum The ADSL Forum was formed in late 1994 to help telephone companies and their suppliers realize the enormous market potential of ADSL. (http://www.adsl.com/) HDSL2.org HDSL2.org is an informational site about HDSL2 (http://www.hdsl2.org/home.htm) Committee T1 Established in February 1984, Committee T1 develops technical standards and reports on the interconnection and interoperability of telecom networks. It is sponsored by the Alliance for Telecommunications Industry Solutions (ATIS) and is accredited by the American National Standards Institute (ANSI). Committee T1 has six technical subcommittees. (http://www.t1.org/) International Telecommunication Union (ITU) Headquartered in Geneva, Switzerland, the ITU is an international organization within which governments and the private sector coordinate global telecom networks and services. (http://www.itu.int/) The European Telecommunications Standards Institute (ETSI) ETSI is a non-profit organization dedicated to telecommunications standards. It unites 696 members from 50 countries. (http://www.etsi.org/) The xDSL Group (xG) A research forum within the Internet Telephony Consortium that examines both the current and future role of xDSL technology. It operates under the Research Program on Communications Policy at the Massachusetts Institute of Technology. (http://rpcp.mit.edu/xdsl/welcome.html http://itel.mit.edu/) Universal ADSL Working Group The UAWG will develop a set of contributions building on the T1.413 standard intended to create quick deployment and adoption of G.Lite. (http://www.uawg.org)

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