CS代写

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 /docProps/thumbnail.jpeg 程序代写 CS代考 加微信: powcoder QQ: 1823890830 Email: powcoder@163.com