Networks Flashcards
Why use LAN
- easier to share files
- share the same hardware
- install software updates all at once
- user account can be stored centrally so users can login from any device on the network
what is the function of a switch
connect devices on a lan, receive data(frames) from one device and transmit to another device on the network with the correct MAC adress
what is the function of a router
transmits data between networks, can be used to connect a LAN to the internet
what is the function of a WAP
connect devices in LAN, wirelessly using WiFi
what is the function of a NIC network interface controller
allows the device to connect to the internet
pros and cons of p2p
pro:
easy to maintain,
no dependence on server
con:
no centralised management, backup is more complicated
peer machines are less reliable as data may be lost if one fails,
machines are prone to slow down when other devices access them
pro con of client server network
pro easier to keep track of files easier to back up easier to manage security servers very reliable and always on
con
expensive to set up and need IR specialist to maintain
server may become overloaded
server dependence
TCP
sets of rules for how devices connect to the network,
split data into packets,
reassembles packet into original data,
chekcs data is send and discovered
IP
responsible for direct data packets across a network
FTP
used to access, edit and move files on other deivces
smpt
used to send emails between servers
pop3
retrieve email from a server, when user download the email, the server deletes it
imap
retrieve email, the server holds the original email until the user deletes it
What’s the difference between a LAN and a WAN
- LAN covers a small geographical area located in one single site
- and all the hardware is owned by one organization
- devices in LAN includes PCs, tablets, printers etc
- WAN connects different LANs in different geographical areas
- organizations hire infrastructures from companies that own and manage the WANs. WANs are much more expensive to set up
Wired Ethernet Connections
- different types of Ethernet cables to connect a device to a LAN
- are fast and reliable
what are CAT 5e or CAT 6
- common ethernet cables are CAT 5e and CAT 6. They are ‘twisted pair’ cables, containing four pairs of copper wires which are twisted together to reduce internal interference
what are coaxial cables
singe copper wire surrounded by a plastic layer for insulation and a metallic mesh which provides shielding from outside interference
what are fibre optics
data transmit as light
- high performance
don’t sufferer interference
- can transmit over a large distance without loss of signal quality
what waves do wireless networks use
radio waves
Bluetooth
direct connection between two devices so data can be shared
rage varies typically 10m
low bandwidth compared to wifi
often used in mobile/wearable devices
Wi-Fi
used by multiple devices to connect to a LAN at the same time
connection rage between 40 - 100m
high bandwidth compared to Bluetooth
wireless NIC
either built-in or you can use dongles
USB dongles
HDMI dongle
factors that affect the performance of networks
- bandwidth: the amount of data that can be transferred in a given time
- number of devices connected/ heavy usage: available bandwidth is shared between the devices on a network. This can be sorted by limiting the bandwidth of each user
- signal quality (wireless), rage and physical obstruction
- wired are generally faster and more reliable than wireless
- choice of hardware and topology
star topology pros and cons
devices all connected to a central switch/server
pros
- failure of one node, rest of the network is unaffected
- easy to add more devices
- better performances than other setups - all devices can transmit data at once with few data collisions
cons
- every device needs a cable to connect to the central server, making it expensive
- switch/server failure will lead to the whole network affected
mesh topology
decentralized, all devices directly or indirectly connected. Data are sent along the fastest route.
- no single point of failure, if one fails data can go a different route
- expensive - a lot of wires are needed, but wireless technology makes it more practical.
what is a network protocol
rules for how devices communicate and how data is transmitted across a network
network standard is a set of agreed requirement for hardware and software
standards are important as they allow manufacturers to create product
MAC address communication on the same network
- every device needs a unique identifier
- MAC address are assigned to all network enabled devices by the manufacturer
- unique and cannot be changed
- 48/64 bit binary numbers and to make easier they are normally connected to hex
- ethernet protocol on LANs and switches read the mac address and use them to direct data to the correct decice
IP address between different networks
IP are used when sending data between TCP/IP networks eg over the internet
IP are assigned manually or automatically before device can access the network
IPv4(32 bits) IPv6(128 bits)
ipv6 split into 16bits
ipv4 split into 8 bits
network protocal layers
self contained
each layer serves the layer above it
data only transferred between adjacent layers (ie 1 with 3, 2 with 1 or 3)
