Computer Network

Networking Relationships
What is a computer network?
What is a Computer Network?
– a network is:
• group of two or more nodes
• connected together by transmission media
• for the purpose of sharing resources
Network Elements
– Node
• a node is any hardware device that is directly
connected to a network
• Examples include:
Assorted types of computer systems
Printers and plotters
Communication hardware (modems, etc.)
Hard Disk Drives
Network Elements
– Transmission Media
• the transmission media consists of the physical
connections, that facilitate the transmission of
signals, between nodes on a network
Telephone lines
Twisted Pair cable
Coaxial Cable
Fiber-optic Cable
Microwave Transmission
Satellite Transmission
Network Elements
– Resource
• a resource is a hardware, software, or data source
• Examples include:
Storage space on Secondary Storage
Ability to send a email from an iPhone
Processing power of high performance CPU
Outputting to high quality printer
Application executed from HD of remote system
Transfer of data files from node to node
Web Pages requested and received
Types of Nodes
– A typical network includes several nodes; some nodes
act as server, some as client, and some as both server
and client
– Server
• a server is a node that makes its resources available to and for
use by other network nodes; therefore, a server shares its
resources across the network
– Client
• a client is a node that requests and uses resources on a network
which are made available and shared by a server on the
How are Resources Shared?
– Resources are shared across networks through
network services
– Service
• a service is a communication scheme or standard
supplying some public demand for shared
resources on a network; scheme consists of user
interaction characteristics and the protocol for
transmitting signal.
Network Services
– Lets look at a specific network, the Internet
– Internet
• the Internet is a global public network facilitating
all sorts of services; the Internet is the largest
world-wide network
• Like in smaller networks, resources are shared over
the Internet using services
Network Services
– Some of the services facilitated by the Internet are:
• E-mail
– the email service is a network service that facilitates exchange
of messages
• World Wide Web
– the world wide web service (WWW) is a network service
facilitating the transfer and display of hypertext document files
• File Transfer Protocol
– the file transfer protocol service (FTP) is a network service that
allows for relatively fast transfer of whole files