OCR A2 ICT G063 - Chapter 3

a) LAN, WAN, Virtual Network

Comparisons

LAN and WAN – LAN is within a locally defined area such as a building but WAN is geographically remote, LAN has a high speed connections within the business but WAN uses external hardware, LAN communication is by internal hardware such as switches and serves but WAN needs an ISP to connect externally to the internet to enable communication between sites, LAN is connected by cables owned by the business but WAN is connected by third party cables, virtual networks can be configured to exist across both multiple LANs and WANs

LAN

Characteristics – within a locally defined area, connected by high speed connections, can have direct connections between machines, connected by cables owned by the company, able to share local peripherals

Organisation – ‘star’ configuration where a hub or switch is at the centre

The heart of the LAN is the ADSL wireless router, the wired connection has a higher bandwidth than the wireless, the router connects every device to the internet and each other

WAN

Characteristics – geographically remote, external hardware, connected by third party cables

It has an external connection (leased line, mobile phone network, satellite link, microwave link)
Virtual Network

Characteristics – a specified group of computers can communicate with each other without detecting the presence of other stations on the physical network, even though other virtual networks may exist using the same physical connections the user of one VN would not notice the others, it can exist across a number of physical LANs or across the internet, communication is only permitted between stations on the virtual network

How VN can be used in their LAN, used by an estate agency  – two or more departments could exist on the LAN but each computer would only communicate with others in the same department, services such as file sharing printing and application sharing would be the same as on a single LAN but on a virtual network these services could be allocated to just those individuals in a particular department, to offer secure remote access to existing resources as if working locally, provide a secure extension of their private network into an insecure environment such as the internet for workers, to separate traffic of the different user groups over their underlying network with strong security features

Computers share the same network hardware and cabling, machines can be added and removed without rewiring (flexible)

VPN – computers to communicate with each other as if they were within a single LAN

VLAN – separating the traffic on a LAN so that different broadcast domains are created, common devices can be grouped together

Standalone vs Networked

Standalone – a computer not connected to a network, all applications are located on the hard disk, you cannot communicate with another computer e.g. a personal laptop

Standalone advantages – sole use of the machine, no problems with bandwidth limitations

Networked – a computer connected to a network is called a ‘workstation’ , you can share information…