31-03-2011, 10:33 AM
presented by:
Miturski Michal
Mirkovski Angel
Sacevski Igor
adsl.ppt (Size: 713 KB / Downloads: 373)
ADSL - Asymmetric Digital Subscriber Line
Introduction
• ADSL is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines
• ADSL is capable of providing up to 50 Mbps, and supports voice, video and data.
• ADSL is the #1 Broadband Choice in the World with over 60% market share
• ADSL is now available in every region of the world
What does ADSL mean
• Asymmetric - The data can flow faster in one direction than the other. Data transmission has faster downstream to the subscriber than upstream
• Digital - No type of communication is transferred in an analog method. All data is purely digital, and only at the end, modulated to be carried over the line.
• Subscriber Line - The data is carried over a single twisted pair copper loop to the subscriber premises
ADSL standards :
• ADSL Speed Comparison
ADSL Range
• In general, the maximum range for DSL without a repeater is 5.5 km
• As distance decreases toward the telephone company office, the data rate increases
• For larger distances, you may be able to have DSL if your phone company has extended the local loop with optical fiber cable
ADSL Speed Factors
• The distance from the local exchange
• The type and thickness of wires used
• The number and type of joins in the wire
• The proximity of the wire to other wires carrying ADSL, ISDN and other non-voice signals
• The proximity of the wires to radio transmitters.
• ADSL network components
• The ADSL modem at the customer premises(ATU-R)
• The modem of the central office (ATU-C)
• DSL access multiplexer (DSLAM)
• Broadband Access Server (BAS)
• Splitter - an electronic low pass filter that separates the analogue voice or ISDN signal from ADSL data frequencies DSLAM.
ADSL Loop Architecture
ADSL Requirements
• Phone-line, activated by your phone company for ADSL
• Filter to separate the phone signal from the Internet signal
ADSL modem
• Subscription with an ISP supporting ADSL
How does ADSL work
• ADSL exploits the unused analogue bandwidth available in the wires
• ADSL works by using a frequency splitter device to split a traditional voice telephone line into two frequencies
ADSL Modulation
• Modulation is the overlaying of information (or the signal) onto an electronic or optical carrier waveform
• There are two competing and incompatible standards for modulating the ADSL signal:
– Carrierless Amplitude Phase (CAP)
– Discrete Multi-Tone (DMT)
Carrierless Amplitude Phase
• Carrierless Amplitude Phase (CAP) is an encoding method that divides the signals into two distinct bands:
– The upstream data channel (to the service provider), which is carried in the band between 25 and 160kHz
– The downstream data channel (to the user), which is carried in the band from 200kHz to 1.1MHz .
• These channels are widely separated in order to minimize the possibility of interference between the channels.
Discrete Multi-tone (DMT)
• Discrete Multi-Tone (DMT) separates the DSL signal so that the usable frequency range is separated into 256 channels of 4.3125kHz each.
• DMT has 224 downstream frequency bins (or carriers) and 32 upstream frequency bins.
• DMT constantly shifts signals between different channels to ensure that the best channels are used for transmission and reception.
• The DMT frequency bands
• Frequency Division Multiplexing (FDM)
• Echo Cancellation
Asynchronous Transfer Mode
• ATM is a connection-orientated technique
• ATM provides cell sequence integrity
• Cells are much smaller than standard packet-switched networks (53 bytes)
• The quality of transmission links has lead to the omission of overheads
• There is no space between cells
Types of ATM services
• Constant Bit Rate (CBR)
• Variable Bit Rate (VBR)
• Unspecified Bit Rate (UBR)
• Available Bit Rate (ABR)
ATM Layer
• The ATM layer transport information across the network
• ATM uses virtual connections for the information transport
• The connections are divided into two levels:
– The Virtual Channels
– The Virtual Path
– This mechanism is used to provide quality of service (QoS)
ATM Connections
• The connection between two endpoints is called a Virtual Channel (VC).
• A Virtual Path (VP) is a term for a bundle of virtual channel links that all have the same endpoints.
• Each VC and VP has a unique identifier
• Virtual paths are used to simplify the ATM addressing structure.
ATM Adaptation Layer (AAL)
• The ATM Adaptation Layer (AAL) converts information from the upper layers into ATM cells
• The standard used for ATM over ADSL services is AAL5
• AAL5 Encapsulation Methods
– Virtual Channel Multiplexing (VCMux)
– LLC/SNAP
– For detailed information please refer to the RFC 1483
ADSL Protocol stacks
• Point-to-Point Protocol over Ethernet over ATM (PPPoEoA)
• Conclusion: Pros & Cons
Why ADSL?
• Simultaneous Internet and voice/fax capabilities over a single telephone line
• Uninterrupted, high-speed Internet access that's always on-line
• Cost-effective solution for society
• Data Security that exceeds other technologies
• Fast download speeds
ADSL disadvantages:
• Distance-sensitive
• Slower upload speeds
• Phone line required
Miturski Michal
Mirkovski Angel
Sacevski Igor
adsl.ppt (Size: 713 KB / Downloads: 373)
ADSL - Asymmetric Digital Subscriber Line
Introduction
• ADSL is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines
• ADSL is capable of providing up to 50 Mbps, and supports voice, video and data.
• ADSL is the #1 Broadband Choice in the World with over 60% market share
• ADSL is now available in every region of the world
What does ADSL mean
• Asymmetric - The data can flow faster in one direction than the other. Data transmission has faster downstream to the subscriber than upstream
• Digital - No type of communication is transferred in an analog method. All data is purely digital, and only at the end, modulated to be carried over the line.
• Subscriber Line - The data is carried over a single twisted pair copper loop to the subscriber premises
ADSL standards :
• ADSL Speed Comparison
ADSL Range
• In general, the maximum range for DSL without a repeater is 5.5 km
• As distance decreases toward the telephone company office, the data rate increases
• For larger distances, you may be able to have DSL if your phone company has extended the local loop with optical fiber cable
ADSL Speed Factors
• The distance from the local exchange
• The type and thickness of wires used
• The number and type of joins in the wire
• The proximity of the wire to other wires carrying ADSL, ISDN and other non-voice signals
• The proximity of the wires to radio transmitters.
• ADSL network components
• The ADSL modem at the customer premises(ATU-R)
• The modem of the central office (ATU-C)
• DSL access multiplexer (DSLAM)
• Broadband Access Server (BAS)
• Splitter - an electronic low pass filter that separates the analogue voice or ISDN signal from ADSL data frequencies DSLAM.
ADSL Loop Architecture
ADSL Requirements
• Phone-line, activated by your phone company for ADSL
• Filter to separate the phone signal from the Internet signal
ADSL modem
• Subscription with an ISP supporting ADSL
How does ADSL work
• ADSL exploits the unused analogue bandwidth available in the wires
• ADSL works by using a frequency splitter device to split a traditional voice telephone line into two frequencies
ADSL Modulation
• Modulation is the overlaying of information (or the signal) onto an electronic or optical carrier waveform
• There are two competing and incompatible standards for modulating the ADSL signal:
– Carrierless Amplitude Phase (CAP)
– Discrete Multi-Tone (DMT)
Carrierless Amplitude Phase
• Carrierless Amplitude Phase (CAP) is an encoding method that divides the signals into two distinct bands:
– The upstream data channel (to the service provider), which is carried in the band between 25 and 160kHz
– The downstream data channel (to the user), which is carried in the band from 200kHz to 1.1MHz .
• These channels are widely separated in order to minimize the possibility of interference between the channels.
Discrete Multi-tone (DMT)
• Discrete Multi-Tone (DMT) separates the DSL signal so that the usable frequency range is separated into 256 channels of 4.3125kHz each.
• DMT has 224 downstream frequency bins (or carriers) and 32 upstream frequency bins.
• DMT constantly shifts signals between different channels to ensure that the best channels are used for transmission and reception.
• The DMT frequency bands
• Frequency Division Multiplexing (FDM)
• Echo Cancellation
Asynchronous Transfer Mode
• ATM is a connection-orientated technique
• ATM provides cell sequence integrity
• Cells are much smaller than standard packet-switched networks (53 bytes)
• The quality of transmission links has lead to the omission of overheads
• There is no space between cells
Types of ATM services
• Constant Bit Rate (CBR)
• Variable Bit Rate (VBR)
• Unspecified Bit Rate (UBR)
• Available Bit Rate (ABR)
ATM Layer
• The ATM layer transport information across the network
• ATM uses virtual connections for the information transport
• The connections are divided into two levels:
– The Virtual Channels
– The Virtual Path
– This mechanism is used to provide quality of service (QoS)
ATM Connections
• The connection between two endpoints is called a Virtual Channel (VC).
• A Virtual Path (VP) is a term for a bundle of virtual channel links that all have the same endpoints.
• Each VC and VP has a unique identifier
• Virtual paths are used to simplify the ATM addressing structure.
ATM Adaptation Layer (AAL)
• The ATM Adaptation Layer (AAL) converts information from the upper layers into ATM cells
• The standard used for ATM over ADSL services is AAL5
• AAL5 Encapsulation Methods
– Virtual Channel Multiplexing (VCMux)
– LLC/SNAP
– For detailed information please refer to the RFC 1483
ADSL Protocol stacks
• Point-to-Point Protocol over Ethernet over ATM (PPPoEoA)
• Conclusion: Pros & Cons
Why ADSL?
• Simultaneous Internet and voice/fax capabilities over a single telephone line
• Uninterrupted, high-speed Internet access that's always on-line
• Cost-effective solution for society
• Data Security that exceeds other technologies
• Fast download speeds
ADSL disadvantages:
• Distance-sensitive
• Slower upload speeds
• Phone line required