LAN
- restricted to a small geographical area
- school, home
- faster
- Fewer errors as data packets are sent over short distances
- Comparatively high as security can be easier to implement over a smaller number of devices and connections.
- owned by individuals or individual organisations.
WAN
- a larger geographical area
- internet is a global WAN
- Several LANs can be connected together to form a WAN.
Adv of networks
- internet connection can be shared
- Users can access their data from different computers on the network.
- File servers can be used to store data in a central location. (keep the data secure and to create a back-up copy. )
- store software in a central location. (reduce software costs as a site licence could be purchased, if available + software updates would only need to be run on the server. )
- Printers can be shared. This means that a number of users can share resources in a company or home, rather than requiring their own.
- Communications can be sent from one computer to another.
- Users can share their data with other users on the network.
Disadv
- high network traffic, network to run slowly and cause frustrating delays.
- whole network fail if one element of the network fails. (This will depend on how the network is structured.)
- Viruses could easily spread from one networked computer to another (if networknot sufficiently protected)
- larger network can be expensive (network requires cabling, several servers, switches and wireless access points) The staffing costs to maintain a network can also be expensive.
Peer-to-peer
Adv
Disadv
- Each comp is a peer
- no central server to manage the network
- no comp had control
- each have equal privileges
- share data and resources
- or keep data private
- network unaffected
- low cost
- no need specialist
- low security
- More peers, harder/slower to run so usually less peers
- no centralised database (worry art backup)
Client server
- dedicated comp/ server to: store data, manage resources, control user access
- central point on network that other comps (client) connect to ( to access data )
servers:
- store database
- assign levels of access
- monitor network traffic
Client server:
ADV
DISADV
network manager
- centralise backup
- security , maintain network
- user data priv
- level of access
- large networks can hv several servers for diff functions ,, improve network efficiency
-
- high cost to set up and maintain
- failure of central server cause whole network to fail
Client server examples
1) Banks:
- Device ( client ) access bank (via internet)
- bank server handle clients
- provide access to online bank facilities
2) Co.
- company (server) hosts a web
- device (client) access the webpage
VPN
- what is
- security
- connecting
- virtual private network
- Once connected, remote computer then has secure access to the LAN’s resources, just as if it were directly connected to the LAN.
- Security implemented through the use of tunnelling protocols and encryption.
- secure shell (SSH) tunnel protocol uses encryption to securely transmit unencrypted data packets across an unsafe network.
To connect to a VPN, 1) user remotely logs on to the network. 2)user’s identity authenticated 3) VPN’s tunnelling protocol sets up an encrypted link to the user’s computer. Data can then be transmitted securely.
Intranet
- privately owned network that use interbent tech
- e.g. a company webpage
- internal use
- internal communicaion
- client server
- several servers
- host web page
- handle email communication
- user accounts - info relevant to org
- secure , confidential
Extranet
- allow external ppl to have access to info on intranet
- VPN
- allow for certain info
- authorised external user
Packet switching
adv
1) TCP (transmission ctrl prtcl) splits data into packets
2) IP routes the packets to diff direction
3) TCP ensures tramission between two pints is siccessful
4) TCP seqences th epackets into correct order at the deistination
- efficient use of WAN
- secure
TCP
How does it work
- ## Transmission control protocol
- ensure that the communications between 2 comps is reliable in order to guarantee that data is received correctly
1) 2 comps verify connection
2) comp will send ‘syn’ to receiver
3) receiver send ‘syn received’
4) data will be sent
5) if data goes astraym TCP will resend
UDP vs TPC
user datagram protocol
- connectionless
- does not ensure data delivery
- does not establish a session (transfer data before receivng end agrees)
- fast
Server
- dedicated server that provode service on behalf of clients
- macihine that multiple clients connect ovr=r a lan/wan
services:
1) access data
2) retrieve web
3) email
Characteristsics of the internet (5)
1) ISP (internet servive provider) to connec to the internet (radiowave, cable)
2) Content provider
- org tha provide content to web’
- distrubute data and info
3) Servers
- majority of data is held by servers
- clients connect to web servers to access web
4) No centralised control
5) constant evolution
VOIP adv disadvantage
- phone in network , internal, free
- if heavy traffic voice scan be distorted
Mobile network
- wireless wan
- use radio to transmit/ receive communication from portable devices
- signal can be weak / interfered
ISDN
- integrated services digital network
- 1990s 2000s
- data transmitted digitally over analogue copper wire
ADSL
- asynchronous digital subscriber line
- broadband
- common connection to the internet
- reliable high speed network
- split between download and upload speed
- homes usually download mor than they upload
SDSL
- synchronous digital subscriber line
- same as ADSL but transmission rates for upload and download equal
Network in web/ video conferencing
- packet switching (video/audio transmission broken into packets)
- resulting packets transit swiftly
- internal, use Lan
- external use wan (internet)
- require high data transmission speed
- ISDN
- SDSL
- ADSL
