The document provides an overview of Digital Subscriber Line (DSL) technology, focusing on its physical layer attributes and components such as the Digital Subscriber Line Access Multiplexer (DSLAM) and various types of DSL including ADSL and VDSL. It explains how DSL uses traditional phone lines to facilitate high-speed internet and phone services while managing issues like signal interference. The document also discusses the role of different infrastructure elements like main distribution frames and DSL filters in maintaining service quality.

1. OSI ModelDNA Lecture
DSL Digital Subscriber Line

2. Physical – Layer 1 Protocol Data Unit
Technical
Plain English
Diagram
Analogy
Reference
Overview
DSL Digital Subscriber Line

3. Physical – Layer 1 Protocol Data Unit
Technical
DSL Digital Subscriber Line
• Connects multiple customer digital subscriber line (DSL)
interfaces to a high-speed digital communications channel
using multiplexing techniques
Method by which multiple analog or digital signals are combined
into one signal over a shared medium.

4. Physical – Layer 1 Protocol Data Unit
Technical
DSL Digital Subscriber Line
• Local Loop: The telephone company wires from a customer to
the telephone exchange or to a serving area interface, often
called the "last mile" (LM).
• Main distribution frame (MDF): A wiring rack that connects
outside subscriber lines with internal lines. It is used to connect
public or private lines coming into the building to internal
networks. At the telco, the MDF is generally in proximity to the
cable vault and not far from the telephone switch
• Handover distribution frame (HDF): Distribution frame
that connects the last mile provider with the service provider’s
DSLAM

5. Physical – Layer 1 Protocol Data Unit
Technical
DSL Digital Subscriber Line
• IP-DSLAM: Internet Protocol Digital Subscriber Line Access
Multiplexer. User traffic is mostly IP based.
• Traditional 20th century DSLAMs used Asynchronous Transfer
Mode (ATM) technology to connect to upstream ATM routers/
switches. These devices then extract the IP traffic and pass it
on to an IP router in an IP network.
DSLAM: Digital Subscriber Line Access Multiplexer
network distribution device for DSL service. The DSLAM port
where the subscriber local loop is connected converts analog
electrical signals to data traffic (upstream traffic for data
upload) and data traffic to analog electrical signals
(downstream for data download).

6. Physical – Layer 1 Protocol Data Unit
Technical
DSL Digital Subscriber Line
• Role of DSLAM is a network switch that functions at Layer 2
Of OSI Model. It cannot reroute between multiple IP
Networks only between ISP devices and end-user connected
Points.
• The DSLAM is switched to a Broadband remote access service
Where end-user traffic is then routed across the ISP network to
the internet.
• The DSLAM may or may not be located in the telephone
exchange and may also serve multiple data and voice
customers within a neighborhood serving area interface
sometime in conjunction with a digital loop carrier.

7. Physical – Layer 1 Protocol Data Unit
Technical
DSL Digital Subscriber Line
• In addition to being a data switch and multiplexer, a DSLAM
Is also a large collection of modems. Each modem on the
aggregation card communicates with a single subscriber’s DSL
modem.

8. Physical – Layer 1 Protocol Data Unit
Technical
Types of DSL Digital Subscriber Line
ADSL
POTS (Plain Old
Telephone System)
Asymmetric digital subscriber line (ADSL) a digital subscriber line (DSL) technology, where data communication technology
enabled faster data transmission over copper telephone lines than a conventional voiceband modem can provide.
Bandwidth and bit rate are said to be asymmetric, meaning greater toward the customer premises (downstream) than the
reverse (upstream). Providers usually market ADSL as a service for consumers for Internet access for primarily downloading
content from the Internet, but not serving content accessed by others.

9. Physical – Layer 1 Protocol Data Unit
Technical
Types of DSL Digital Subscriber Line
VDSL Very-high-bit-rate Digital Subscriber Line commonly used for higher bandwidth requirements. VDSL
offers speeds of up to 52 Mbit/s downstream and 16 Mbit/s upstream, over a single flat untwisted
or twisted pair of copper wires using the frequency band from 25 kHz to 12 MHz.
Second-generation systems (VDSL2; ITU-T G.993.2 approved in February 2006) use frequencies of up to 30 MHz to
provide data rates exceeding 100 Mbit/s simultaneously in both the upstream and downstream directions. Maximum
available bit rate is achieved at a range of about 300 metres (980 ft); performance degrades as the local loop attenuation
increases.
POTS (Plain Old
Telephone System)

10. Physical – Layer 1 Protocol Data Unit
Technical
Types of DSL Digital Subscriber Line
VDSL2 is an enhancement to VDSL designed to support the wide deployment of triple play services such as voice, video, data
and high-definition television (HDTV) VDSL2 is intended to enable operators and carriers to gradually, flexibly, and cost-efficiently
upgrade existing xDSL infrastructure.
Etherloop: is a kind of DSL technology that combines the features of Ethernet and DSL. It allows the combination of voice and data
transmission on standard phone lines. Under the right conditions it will allow speeds of up to 6 megabits per second over a distance of
up to 6.4 km.

11. Physical – Layer 1 Protocol Data Unit
Residential & Enterprise Diagram
DSL Digital Subscriber Line
ATU-R = “DSL Modem” POTS Splitter = DSL Filter
Central Office = Telco Provider ISP “Internet Service Provider”

12. Physical – Layer 1 Protocol Data Unit
Plain English
DSL Digital Subscriber Line
• DSL uses traditional phone lines to send voice and data to
homes and business. DSL splitters are used to separate the
noise on the phone line into two separate lines Voice and Data.
“Digital Subscriber Line – DSL “Data” & Phone ”Voice” Splitter
• The DSL signal can cause static, noise, squealing (similar to fax
tones), caller ID disruption and other issues on your line. DSL
filters block the high frequency DSL signals from being
transmitted to the telephone.DSL Filter
• By using a DSL filter both the phone and data are split into two separate lines
that are isolated, permitting a single telephone line to be used for both telephone
calls and internet at the same time.

13. Physical – Layer 1 Protocol Data Unit
DSL Diagrams
DSL Digital Subscriber Line

14. Physical – Layer 1 Protocol Data Unit
DSL Diagrams
DSL Digital Subscriber Line

15. Physical – Layer 1 Protocol Data Unit
Analogy
DSL Digital Subscriber Line
• DSL is a term that is used to describe a service that gives commercial businesses and residential homes
access to internet and phone service with the option to include TV services.
• An ISP is both an internet service provider and telecommunication “Telco” provider. So, many times
they will offer you discounts for combining those services together and use an access model charging
you a single fee that cover it all.
• Your services are all based on personal preference with a cost that meets your personal and business
requirements for speed, reliability and convenience.

16. Physical – Layer 1 Protocol Data Unit
References
Digital Subscriber Line – additional links within
https://en.wikipedia.org/wiki/Digital_subscriber_line
Asymmetric digital subscriber line
https://en.wikipedia.org/wiki/Asymmetric_digital_subscriber_line
VDSL
https://en.wikipedia.org/wiki/VDSL
How can I reduce static and noise on my phone
https://telephones.att.com/product-support/faqs/basic-troubleshooting-tips/how-
can-i-reduce-static-and-noise-on-my-phone