Definition: the computer network is mainly formed by a number of interconnected generic, programmable hardware, and the hardware is not designed to achieve a particular purpose (e.g., data transmission or video signal). Application of these programmable hardware can be used to convey many different types of data, and can support a wide and growing
There are several categories of computer networks:
1. In accordance scope Category:
WAN WAN (Wide Area Network): the role usually in the range of tens to thousands of kilometers. A metropolitan area network MAN (Metropolitan Area Network): effect from about 5 to 50 km. Local area network LAN (Local Area Network): confined to a smaller range (eg about 1 km). Personal Area Network PAN (Personal Area Network): a small range, about 10 meters.
2. User Category:
1. public network (public network):
Payment of fees can use
2. private network (private network):
For the needs of special operations and build networks
3. How to classify user connected to the Internet
Access network AN (Access Network) or residents called local access network access network
Between the access network is a network from a client system to the first router in the Internet (also referred to as an edge router).
Computer network performance:
1. Performance Indicators
Rate: bit (bit) is a unit of measurement means is a source of Binary digit binary number, the data rate is the transmission rate, also known as data rate and bit rate. Usually refers to the nominal rate
Bandwidth: bandwidth refers to a signal having a frequency width units (Hz, kHz, etc.), the bandwidth of the channel capacity of the network represents transmission of data, representing the highest data rate in a unit of the network world through the channel
Throughput: the amount per unit time by a data network (interface channel), and restricted bandwidth and speed of
Delay (delay / latency) refers to the data from one network to the other end of the time, also known as delay.
The total delay = delay + transmission propagation delay + delay + Queuing delay processing:
Transmission delay is also called the transmission delay time to the data transmission medium entering node required = bit / (bit / s), that is, from the first to the last bit of the transmission ending time needs.
Propagation delays: the propagation time of electromagnetic waves in the channel takes
= Propagation delay channel length / channel signals in the propagation rate
Processing delay: the host or router receives a packet takes to process packets delay
Queuing delay: the input packet output queue router queuing delay experienced by the process
Delay-bandwidth product:
Propagation delay bandwidth product delay X = bandwidth (in bits link length)
Return time: the sender transmits data reception confirmation data functions