slides02 Flashcards
what is a network
A network is any means to connect entities together so they can communicate
Reasons to network include:
- Resource sharing
- Communication and collaboration
- Information gathering
- Reliability through replication
- Entertainment
Existing networks include:
- The telephone system
- The mobile phone system
- TV and radio
- System control networks, e.g., Controller Area Network (CAN bus) in cars
- Cable networks
- Data networks
- The Internet
Metcalfe’s Law
The value of a network expands exponentially as the number of users increases
Classification by size of network
- LAN Local Area Network
- MAN Metropolitan Area Network
- WAN Wide Area Network
- PAN Personal Area Network, WPAN (wireless)
Narrowband def
Narrowband refers to data communication and telecommunications tools, technologies and services that utilize a narrower set or band of frequencies in the communication channel. These utilize the channel frequency that is considered flat or which will use a lesser number of frequency sets.
Narrowband is typically implemented in telecommunication technologies to carry voice data on a limited number of frequency sets. The size of the message sent via a narrowband technique utilizes lesser bandwidth than the cumulative bandwidth of the underlying channel.
Narrowband is also used in sending audio spectrums that consume a restricted range of frequencies. The US FCC has allocated a specific range of frequency for mobile radio services based on narrowband that spans from 50cps to 64kbps.
Broadband def
Broadband is a high-data-rate connection to the Internet. The technology gets its name as a result of the wide band of frequencies that isavailable for information transmission. Information can be multiplexed and sent on numerous channels, allowingmore information to be transmitted at a given time.
The standard broadband technology in most areas is cable Internet and assymetric digital subscriber line (ADSL). The latest technologies are very-high-bitrate DSL and optical fiber connections.
Broadband is also known as wideband.
Broadband allows users to access the Internet and its related services at higher speeds than those available through dial-up Internet access services. The speeds differ based on the type and level of services offered. Broadband services deployed for residential consumers provide faster downstream speeds than upstream speeds.
There are two groups of broadband technologies: fixed-line broadband and wireless technologies. Fixed-line solutions communicate through physical networks that provide direct wired connection from customer to service supplier. Wireless solutions, on the other hand, use radio or microwave frequencies to provide connections between operator and customer networks.
Classification by technology
- Voiceband modem (V series of standards, V.92)
- Local Wired (Ethernet)
- Longerdistancewired.ADSL(ADSL2,ADSL2+,…)
- Optical Fibre (FTTP)
- Hybrid(VDSLwithFFTC,G.fastwithFTTdp,…)
- Cable (DOCSIS)
- LocalWireless(Wi-Fi,Bluetooth,…)
- Longerdistancewireless(3G,4G/LTE,5G,WiMAX,…)
- Very long distance wireless: satellite
- Power line
ADSL
Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide.
FTTP
Fiber To The Premises (FTTP) is a fiber optic cable delivery medium that provides Internet access directly to a user or groups of users from an Internet service provider (ISP).
VDSL
Very-high-bit-rate digital subscriber line (VDSL) and very-high-bit-rate digital subscriber line 2 (VDSL2) are digital subscriber line (DSL) technologies providing data transmission faster than asymmetric digital subscriber line (ADSL).
FFTC
VDSL Vectoring is a method of increasing the speed of a given VDSL2 (G.993.2/FTTC) line so that it can achieve a higher speed than it would otherwise achieve. It does so by using noise cancelling technology to reduce interference from adjacent lines or other services or plant (equipment).
Advertised speeds
ISPs advertise the connection speeds to the subscriber, and not the speeds between the subscriber and the Internet.
In the UK the connection to the home is almost always a BT phone line and ADSL, but fibre is becoming increasing popular.
If that is the case then The access speed will be limited by these BT lines regardless of the ISP you choose.
However that doesn’t mean that all providers will provide the same overall connection quality as-.
The connection between the ISP and the Internet is usually over fiber and is fast, but it is shared by many subscribers.
Therefore if the ISP overloads the link to the Internet it slows the connection from subscriber to Internet.
So your Connection to the ISP could be 6Mbits/s but from you to the Internet it could be only 3 Mbits/s.
managed by different groups
- department
- university
- region
- country
- world
web
The Web, or World Wide Web (W3), is basically a system of Internet servers that support specially formatted documents