Introduction
Access Networks: DSL, Cable Network, FTTH, Home Network, Enterprise Network
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Access Networks and Physical Media
Q: How to connect end systems to edge router?
mobile access networks
residential access nets
institutional access networks (school, company)
keep in mind:
bandwidth (bits per second) of access network?
shared or dedicated?
central office
Analog data and
Telephone signals
Access net: DSL
digital subscriber line
central office
digital data
Analog data and
Telephone signals
Access net: DSL
digital subscriber line
central office
voice, data transmitted
at different frequencies over
dedicated line to central office
DSL access
multiplexer
5-10 miles
DSLAM – Digital Subscriber Line Access Multiplexer
– performs analog to digital signal conversion
Hundreds or even thousands of households connect to a single DSLAM.
digital data
Analog data and
Telephone signals
digital data
Access net: DSL
digital subscriber line
central office
voice, data transmitted
at different frequencies over
dedicated line to central office
DSL access
multiplexer
5-10 miles
DSLAM – Digital Subscriber Line Access Multiplexer
– performs analog to digital signal conversion
Hundreds or even thousands of households connect to a single DSLAM.
digital data
Analog data and
Telephone signals
digital data
Access net: DSL
digital subscriber line
High-speed downstream channel: 50kHz to 1 MHz band
Medium-speed upstream channel: 4KHz to 50 kHz band
Ordinary two-way telephone channel: 0 to 4KHz band
Frequency Division Multiplexing
central office
voice, data transmitted
at different frequencies over
dedicated line to central office
DSL access
multiplexer
5-10 miles
DSLAM – Digital Subscriber Line Access Multiplexer
– performs analog to digital signal conversion
Hundreds or even thousands of households connect to a single DSLAM.
digital data
Analog data and
Telephone signals
digital data
Access net: DSL
digital subscriber line
use existing telephone line to central office DSLAM
data over DSL phone line goes to Internet
voice over DSL phone line goes to telephone net
< 2.5 Mbps upstream transmission rate (typically < 1 Mbps)
< 24 Mbps downstream transmission rate (typically < 10 Mbps)
ASYMMETRIC ACCESS
Works only within 5 to 10 miles from the CO.
VDSL (Very High-Speed DSL) and Ultra Fast Broadband now exists!
It is highly recommended that the premise wiring is upgraded and the installation of a VDSL2-compatible splitter is a good quality VDSL2 service. A VDSL2 capable modem is required.
As with ADSL2+, download and upload speeds may be limited by a number of factors:
the condition of the copper line
copper loop length
type of cable containing the cooper loop
the presence of other services in a cable sheath containing the copper loop - these may cause interference to VDSL2
presence and degree of external interference
the modem performance
condition of the wiring within the end user's premises. It is recommended that screened Cat.5e STP cable is used between the VDSL2 compatible splitter and the modem
For more information:
http://www.chorus.co.nz/broadband-technology#sthash.zgZRDy7j.dpuf
For extra reading
Central Office / Exchange
http://www.flickr.com/photos/afiler/3825218687/sizes/m/
Example: A central office in Dakota, U.S.A.
The max. transmission rate can be limited by:
the distance between the home and the CO.,
the gauge of the twisted-pair line, and
the degree of electrical interference.
Limit: 5-10 miles from the CO.
No windows! Not for humans
Requires that the residence be closer to the CO
up to 8000
Hyperfibre (up to 8 Gbps!)
Test your broadband speed
https://www.speedtest.net
Some related information
https://www.chorus.co.nz/broadband/fibre
Fibre internet
Here are some links that you might want to check out, if you want to find your internet broadband speed,
And if you want to have a look at the various fibre connections available in NZ.
cable headend
frequency division multiplexing: different channels transmitted
in different frequency bands
Typically 500 to 5,000 homes connect
Fiber node
digital data
Analog data and
Video signals
digital data
Neighbourhood junction
Coaxial cable
cable modem
termination system
(similar to DSLAM)
Fiber cable
Access net: cable network
Introduction
data, TV transmitted at different
frequencies over shared cable
distribution network
cable headend
cable modem
termination system
HFC: hybrid fiber coax
asymmetric: up to 42.8Mbps downstream transmission rate, 30 Mbps upstream transmission rate
Downstream channel is shared
Upstream channel is shared
network of cable, fiber attaches homes to ISP router
homes share access network to cable headend
unlike DSL, which has dedicated access to central office
Fiber cable
Fiber node
digital data
Analog data and
Video signals
digital data
Typically 500 to 5,000 homes
Access net: cable network
Access net: FTTH
ONT – Optical Network Terminator
OLT – Optical Line Terminator
OLT - performs electrical(digital) to optical signal conversion, and vice-versa
Fibre To The Home (FTTH)
Passive Optical Network architecture
Access net: home network, 1
to/from headend or central office
cable or DSL modem
router, firewall, NAT-enabled
wired Ethernet
(100 Mbps, 1 Gbps)
wireless access
point (54 Mbps)
often combined
in single box
DSL or Cable Internet
Modem/router/access point
Mesh WiFi System
https://main.prod.vodafonenz.psdops.com/_document?id=00000174-9e1b-d0cd-a57e-9fffd98e0000
Mesh Wifi: https://www.vodafone.co.nz/online-shop/accessory/deco/x20-mesh-wifi-system/
Optical Network Terminator
Fibre optic link
Access net: home network, 2
Fibre To The Home (FTTH)
Introduction
typically used in companies, universities, etc
10 Mbps, 100Mbps transmission rates (for users)
1Gbps, 10Gbps transmission rates (for servers)
today, end systems typically connect into Ethernet switch
institutional mail,
web servers
institutional router
institutional link to
ISP (Internet)
Enterprise access network
Note: These transmission rates improve as technology advances
Computer Networking: A Top-Down Approach, , , Pearson/
Parts of the lecture slides were taken from
References
https://www.chorus.co.nz/broadband/fibre
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