IB CS Topic 3: Networks

Network

when two or more computers are connected with one another for the purposes of communicating data####LAN

The password needs to be transmitted over the network to receiver to allow them to read the message

Some encryptions are designed to have backdoors built in####User ID

A userid and password are used to identify the specific communicating user.

Access rights to the network can be set for each user User groups can be created to manage user rights in batches. A userID can be stolen

system can be bypassed

Does not protect against intercepting messages in the network####Permissions

As well as passwords to enable users to login, each user also has a set of permissions associated with their logon name or group. Some users, administrators or super-users, can look in any data file, change user passwords and delete any file on the system. Ordinary users can only access their own files and use specified resources such as printers and CD burners####Data packet

Throughput: Actual transfer rate, which is affected by traffic.

Bottleneck: When a network has many segments, the slowest segment creates a bottleneck, which makes throughput only as fast as its slowest component.

Goodput: Measures the transfer rate of usable data.

-Amount of computers on the network.

-Interferences

-Type of File sent####Hub

A hardware device that physically connects parts of a network.####Router

Lowest bandwidth

Least attenuation, so less need for repeaters####Microwave

3GHz-300GHz

Medium bandwidth

Medium attenuation

Can be directed, focused, and can penetrate walls####Infrared

300GHz-400THz

Greatest bandwidth

Highest attenuation, mostly for indoor use

Cannot penetrate walls

Can be focused towards a receiver####Switch vs. Hub

Hub transfers data to every port (legacy)

Switch only goes to desired port

BOTH interconnect nodes####Lossy vs. Lossless compression

terms that describe whether or not, in the compression of a file, all original data can be recovered when the file is uncompressed.####Packet Switching