Leveraging Technology For Competitive Advantage

DSL For Small to Medium-Sized Businesses

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TABLE OF CONTENTSAbstract 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 6

Dsl equipment 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 oftheir 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 medium-

sized 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 high-

speed 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.

Unused

Voice

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WHAT IS DSL?

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

bandwidth connectivity to homes and small businesses over

ordinary copper telephone lines. Connection speeds for DSL range

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

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

bypasses the voice network, placing a high-speed digital link on the

copper telephone line and routing information directly to a packet-

switching data network for efficient wide-area transmission.

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

more capacity out of a copper telephone line without interfering

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

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

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

continuously connected, providing “always on” access to the

Internet and company Intranet.

DSL achieves higher data transfer rates than traditional modems or

ISDN technology by utilizing more of the available bandwidth

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.

HISTORY OF DSL

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

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

materialized, the demand for bandwidth generated by growing

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

led to the development of Internet access via DSL.

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

act required the Incumbent Local Exchange Carriers (ILECs) —

local telephone companies that control the local infrastructure —

to open up their services and network elements, making them

available for resale by competitors. These companies are called

Competitive Local Exchange Carriers (CLECs) and they make DSL

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

Central Office (CO). This equipment consolidates traffic from

individual DSL connections into backbone networks, connecting to

Internet Service Providers (ISPs) or corporate networks.

DSL uses a broad range of frequencies to deliver higher transfer rates

over ordinary phone lines.

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BENEFITS OF DSL TECHNOLOGY

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

reduced expenses. Following is a comprehensive look at some of

these benefits:

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

attachments or web pages to download; Files that take several

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

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

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

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

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

That equates to two hundred-fifty additional man-hours per day in

increased productivity – which translates directly to the bottom line.

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

are becoming more common as Internet usage expands. It also

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

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

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.

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

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

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

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

with no usage limit.

Lower cost per connection: Some businesses with hundreds of

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

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

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.

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

pair infrastructure makes it less expensive to install than other

services, which often require the laying of additional cable.

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

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

plus a minimal monthly fee.

Fixed cost for easy budgeting / expense control: Most service

providers bill for ISDN service on a call-by-call, minute-by-minute

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

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

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

expense control.

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

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

the bandwidth available to the end user is more consistent.

Easy to manage: DSL allows you to focus your efforts on growing

your company, rather than managing Internet access.

Online collaboration with vendors / partners / branch offices:

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 ApplicationsBelow 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

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.

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

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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

connections into backbone networks connecting to ISPs or

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

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

CPE: (Customer Premises Equipment):

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

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

so care must be taken to ensure compatibility.

Single User CPE includes:

• Internal PCI card

• USB modems

• 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.)

Multiuser CPE includes:

• LAN modems (or bridges)

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

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

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

to a LAN through an external hub (or switch) with standard

10Base-T cabling.

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

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

frequency data communications from the low-frequency voice

communications.

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

placed on phone lines to filter out interference between the high

and low frequencies.

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

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

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

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

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

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

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

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

desktop is essential for quality of service and guaranteed

bandwidth, as in video-on-demand applications.

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

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

signaling and encapsulation are performed in the PC). These

devices are slightly more expensive than internal solutions, but add

value by minimizing customer support.

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.

Ethernet DSL Modem

• Ethernet DSL modems attach to internal Ethernet cards when

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

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

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

modems encapsulate Ethernet frames into ATM for transmission,

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

• The Ethernet DSL modem offers immediate compatibility with

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

simple with little configuration required, though there is some

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

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

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

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

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

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-to-

point connection between a consumer’s home or business and the

telephone company switching office. Conversely, cable is a point-to-

multipoint 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

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.

• 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.

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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.

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,

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 Next-

Generation 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

• 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

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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.

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

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:

• 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.

13

POLICY SWITCH IMPROVESNETWORK 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.

14

SUMMARY

DSL technology is expanding the availability of high-speed Internet access and network-to-

network 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 compatibilitywith 10 Base-T networks running at 10 Mbps.

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

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

A

Access Line - The physical telecommunications circuit connectingan end user location with the serving Central Office (CO) in alocal network environment. See also Local Loop.

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

Access Nodes - Points on the edge of the access network thatconcentrate individual access lines into a smaller number offeeder lines.

Access Rate - The transmission speed of the physical access circuitbetween the end user location and the local network. This isgenerally measured in bits per second; also called AccessSpeed.

Adapter Card - Circuit board or other hardware that provides thephysical interface to a communications network; an electronicsboard installed in a computer which provides networkcommunication capabilities to and from that computer; a cardthat connects the DTE to the network. Also called a NetworkInterface Card (NIC).

Asymmetric digital subscriber line (ADSL) - A group of DSLtechnologies that reserve more bandwidth in one direction thanthe other, which is advantageous for users that do not needequal 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, andSDSL) enable the connection to be alwayson in a fashion similar to a LAN.

Analog - An electrical signal or wave form in which the amplitudeand/or frequency vary continuously, such as a voice signal overa Plain Old Telephone System (POTS) line.

American National Standards Institute (ANSI) - An official bodywithin the United States delegated with the responsibility ofdefining standards.

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

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

Available Bit Rate - Provides a guaranteed minimum capacity butallows data to be sent at higher capacities when the network isfree.

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

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

B

Backbone - The part of a communications network that handles themajor traffic using the highest-speed, and often longest, pathsin the network.

Bandwidth - A measure of capacity of communications media.Greater bandwidth allows communication of more informationin a given period of time. Bandwidth is generally describedeither in terms of analog signals in units of Hertz (Hz), whichdescribes the maximum number of cycles per second, or interms of digital signals in units of bits per second.

Bit - A single unit of data, either a one or a zero, used in digital datacommunications. 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 networksthat are able to carry several services at the same time, such asdata, voice, and video.

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APPENDIX A: GLOSSARY OF TERMS

Byte - A compilation of bits, seven bits in accordance with ASCIIstandards and eight bits in accordance with EBCDIC standards.

C

Carrier - an electromagnetic wave or alternating current which ismodulated to carry signals in radio, telephonic, ortelegraphic transmission.

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

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

Circuit-switched network - A type of network in which a continuouslink is established between a source and a receiver. Circuitswitching is used for voice and video to ensure that individualparts of a signal are received in the correct order by thedestination site.

Competitive local exchange carrier (CLEC) - An American term fora telephone company that was created after theTelecommunications Act of 1996 made it legal for companiesto compete with the ILECs. Contrast with ILEC.

Customer premises equipment (CPE) - Any piece of equipment in acommunication system that resides within the home or office.Examples include modems, television set-top boxes, telephonesand televisions.

D

Dedicated connection - A communication link that operatesconstantly.

Dial-up connection - A data communication link that is establishedwhen the communication equipment dials a phone number andnegotiates a connection with the equipment on the other end ofthe link.

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

Digital subscriber line (DSL) - A data communications technologythat transmits information over the copper wires that make upthe local loop of the public switched telephone network (Seelocal loop).) It bypasses the circuit-switched lines that make upthat network and yields much faster data transmission ratesthan analog modem technologies

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

Discrete multi-tone modulation (DMT) - A method of transmittingdata on copper phone wires that divides the available frequencyrange into 256 sub-channels or tones, and which is used forsome types of DSL.

DNS - domain name service - The protocol used for assigning textaddresses (such as www.nortelnetworks.com) for specificcomputers and computer accounts on the Internet.

E

E-1 - A dedicated digital communication link provided by aEuropean telephone company that offers 2.048 megabits persecond of bandwidth, commonly used for carrying traffic to andfrom 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 telephoneequipment, used in data transmission to improve thebandwidth of the line.

F

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

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

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

G

G.dmt - A kind of asymmetric DSL technology, based on DMTmodulation, that offers up to 8 megabits per seconddownstream bandwidth, 1.544 Megabits per second upstreambandwidth. “G.dmt” is actually a nickname for the standardofficially known as ITU-T Recommendation G.992.1. (SeeInternational Telecommunications Union.)

17

APPENDIX A: GLOSSARY OF TERMS

G.lite [pronounced “G-dot-light”] - A kind of asymmetric DSLtechnology, based on DMT modulation, that offers up to 1.5megabits per second downstream bandwidth, 384 Kilobits persecond upstream, does not usually require a splitter and iseasier to install than other types of DSL. “G.lite” is a nicknamefor the standard officially known as G.992.2. (See InternationalTelecommunications Union.)

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

Graphical user interface (GUI) - A computer operating system thatis based upon icons and visual relationships rather than text.Windows and the Macintosh computer use GUIs because theyare more user friendly.

H

Hertz - See frequency.

High bitrate digital subscriber line (HDSL) - A symmetric DSLtechnology that provides a maximum bandwidth of 1.5megabits per second in each direction over two phone lines, or2 Megabits per second over three phone lines.

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

Hypertext - Documents or other information with embedded linksthat enable a reader to access tangential information at specificpoints in the text.

Hypertext markup language (HTML) - The computer language usedto create hypertext documents, allowing connections from onedocument or Internet page to numerous others. HTML is theprimary 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 inHypertext Markup Language (HTML).

Hz - See frequency.

I

Incumbent local exchange carrier (ILEC) - A large telephonecompany that has been providing local telephone service in theUnited States since the divestiture of the AT&T telephonemonopoly in 1982.

Institute of Electrical and Electronics Engineers (IEEE) - Amembership organization comprised of engineers, scientistsand students that sets standards for computers andcommunications.

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

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

International Telecommunication Union (ITU) - A United Nationsorganization that coordinates use of the electromagneticspectrum and creation of technical standards fortelecommunication and radio communication equipment.

International Telecommunication Union/TelecommunicationStandardization Sector (ITU-T) - The branch of the ITU that isresponsible for telecommunication standardization.

Internet Engineering Task Force (IETF) - The standardsorganization that standardizes most Internet communicationprotocols, including Internet protocol (IP) and hypertexttransfer protocol (HTTP).

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

Internet service provider (ISP) - An organization offering andproviding Internet access to the public using computer serversconnected directly to the Internet.

Intranet - A network serving a single organization or site that ismodeled after the Internet, allowing users access to almost anyinformation 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.

ISDN digital subscriber line (IDSL) - A type of DSL that uses ISDNtransmission 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 ofcomputers to each other or to a central server so that thecomputers can share programs and files.

18

APPENDIX A: GLOSSARY OF TERMS

Local exchange carrier (LEC) - A local telephone company. LECsprovide telephone service for phone calls originating andterminating within a single LATA.

Local loop - The copper lines between a customer’s premises and atelephone 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 digitaldata into analog signals and vice-versa for transmission overa telephone line.

Multicast - The transmission of information over the Internet to twoor 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 ofnetworked telephone and associated services, usually in the U.S.

Network service provider (NSP) - A high-level Internet provider thatoffers high-speed backbone services.

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

O

Optical carrier 3 (OC-3) - A fiber optic line carrying 155 megabitsper second; a U.S. designation generally recognized throughoutthe telecommunications community worldwide.

P

Packet-switched network - A network that allows a message to bebroken into small “packets” of data that are sent separately bya source to the destination. The packets may travel differentpaths and arrive at different times, with the destination sitesreassembling them into the original message. Packet switchingis used in most computer networks because it allows a verylarge amount of information to be transmitted through a limited bandwidth.

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

Plain old telephone service (POTS) - An acronym identifying thetraditional function of a telephone network to allow voicecommunication between two people across a distance. In mostcontexts, POTS is synonymous with the public switchedtelephone network (PSTN).

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

POTS splitter - A device that uses filters to separate voice from datasignals 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 DSLthat uses carrierless amplitude phase modulation, divides theavailable frequencies into discrete sub-channels and alsomaximizes performance by adjusting the transmission to thequality of the phone line while in use.

Regional Bell Operating Company (RBOC) - One of the seven localtelephone companies formed upon the divestiture of AT&T in1984. 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 computernetwork that directs and controls the flow of data through thenetwork.

S

SDSL - Symmetric Digital Subscriber Line - This technology providesthe same bandwidth in both directions, upstream anddownstream. That means whether you’re uploading ordownloading information, you have the same high-qualityperformance. SDSL provides transmission speeds within aT1/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 copperwire. This option is ideal for small and medium sizedbusinesses that have an equal need to download and uploaddata over the Internet.

T

T-1 - A dedicated digital communication link provided by atelephone company that offers 1.544 megabits per second ofbandwidth, commonly used for carrying traffic to and fromprivate business networks and Internet service providers.

19

APPENDIX A: GLOSSARY OF TERMS

Telecommuting - The practice of using telecommunicationtechnologies to facilitate work at a site away from thetraditional office location and environment. teleconference -Interactive, electronic communication among three or morepeople at two or more sites. Includes audio-only, audio andgraphics, and video-conferencing.

Time division multiplexing (TDM) - A digital data transmissionmethod that takes signals from multiple sources, divides theminto 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.

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

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

U

Uniform Resource Locator (URL) - A text-based address used toidentify specific resources on the Internet, such as web pages.URLs are arranged in a hierarchical form that specifies thename of the server on which a resource is located and thename of the file on that server.

Universal ADSL Working Group (UAWG) - An organizationcomposed of leading personal computer industry, networkingand telecommunications companies with the goal of creatingan interoperable, consumer-friendly ADSL standard titled theG.992.2 standard, and commonly referred to as the G.lite standard.

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

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

V

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

VDSL - See very high bitrate digital subscriber line. very high bitratedigital subscriber line (VDSL) - An asymmetric DSL thatdelivers from 13 to 52 megabits per second downstreambandwidth and 1.5 to 2.3 megabits per second upstream.

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

W

WAN (Wide area network) - A network that interconnectsgeographically-distributed computers or LANs.

X

X.25 data protocol - A packet switching standard developed in themid-1970s for transmission of data over twisted pair copper wire.

xDSL – Generic term that covers all “flavors” of DSL (e.g., ADSL,VoDSL, etc.)

20

APPENDIX B: REFERENCES APPENDIX C: DSL RESOURCES ON THE INTERNETIETF 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)

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)