Introduction
A protocol is a standard by which communication takes place between network devices.
What is TCP/IP ?
Transmission Control Protocol / Internet Protocol.
TCP/IP is one of the core network protocols on top of which most other
protocols are built. TCP watches network traffic to detect problems and
ensure that data is safely transferred between network devices.
What is UDP ?
User Datagram Protocol
(also Universal Datagram Protocol). Controls traffic between network
devices, but does not attempt any error correction. It is used for
protocols where speed is more important than accuracy or error
correction is handled by the client software. It doe not gaurantee the
delivery of packets.
What is SMB/CIFS ?
Server Message Block / Common Internet File System.
SMB is the File transfer protocol commonly used by Windows computers.
Mac OS X and Linux/UNIX now commonly include an implementation of SMB
known as Samba. This protocol uses TCP port 445.
What is AFP ?
Apple Filing Protocol.
AFP is the file transfer protocol commonly used by Macintosh computers.
This protocol is preferred for Mac transfers since it supports Unicode
file names, resource forks, and other Mac OS specific attributes. This
protocol uses TCP ports 548 and/or 427.
What is NFS ?
Network File System.
NFS is the file transfer protocol commonly used by UNIX/Linux
computers. Due to its UNIX roots, Mac OS X also supports NFS. This
protocol uses TCP port 1025.
What is HTTP ?
Hypertext Transfer Protocol.
This is the protocol used for most web traffic. Your iomega network
device uses either this protocol or HTTPS (see below) to host the
configuration
interface. It will not allow you to host other websites
on the device. This protocol usually uses TCP port 80, but may use
8008, 8080, 16080, etc.
What is HTTPS ?
Hypertext Transfer Protocol Secure.
This protocol is most commonly used for websites and combines HTTP
transfers with SSL or TLS encryption. Most web browsers will issue a
warning if the HTTPS server’s certificate cannot be verified. HTTPS
typically uses TCP port 443.
What is FTP ?
File Transfer Protocol.
FTP is a common Internet protocol used for file transfers. Although FTP
is a very common protocol, it still may require special client software
in some situations. For example, the Mac OS X finder supports FTP, but
is Read-Only—You will need special software to use FTP to upload files.
This protocol uses TCP port 21.\
What is Bluetooth ?
Bluetooth
is a wireless transfer protocol that is used to transfer small files
such as calendars, photos, and contacts over short distances (using OBEX
or Object Exchange Protocol). It is also used to control devices such
as mice wirelessly.
What is NTP ?
Network Time Protocol. NTP synchronizes the time between a client and a time server. This protocol uses UDP port 123.
What is SMTP ?
Simple Mail Transfer Protocol.
SMTP is a simple email protocol. SMTP is usually only used for outbound
emails such as email notifications sent by your school, college or
offices. By default, this protocol uses UDP port 123.
Network Topologies
CLASSIFICATION OF NETWORKS
There are mainly three types of networks:
1) LAN (Local Area Network)
2) MAN (Metropolitan Area Network)
3) WAN (Wide Area Network)
Local Area Network (LAN)
LAN
is a group of computers located in the same room, on the
same floor or in the same building that are connected to
form a single network as to share resources such as disk
drives , printers, data, CPU, fax/modem, application. etc.
There are essentially five components of a LAN:
1.
Network devices such as Workstations, printers, file servers
which are normally accessed by all other computers.
2.
Network Communication Devices i.e., devices such as hubs,
routers, switches etc. used for network connectivity.
3.
Network Interface Cards (NICs) for each network device required
to access the network. It is the interface between the
machine and the physical network.
4. Cable as a physical transmission medium.
5.
Network Operating System –software applications required to
control the use of network operation and administration.
Metropolitan Area Network (MAN)
Metropolitan
area networks, or MANs, are large computer network usually
spanning a city. They typically use wireless infrastructure or
Optical fiber connections to link their sites.
Characteristics of MAN
1) It generally covers towns and cities (50 kms)
2) It is developed in 1980s.
3) Communication medium used for MAN are optical fibers, cables etc.
4) Data rates adequate for distributed computing applications.
Wide Area Network (WAN)
Wide
Area Network is a network system connecting cities,
countries or continents, a network that uses routers and
public communications links. The largest and most wellknown
example of a WAN is the Internet.
Characterstics of WAN
1) It generally covers large distances (states, countries, continents).
2) Communication medium used are satellite, public telephone networks which are connected by routers.
3) Routers forward packets from one to another in a route from the sender to the receiver.
Difference between LAN, WAN and MAN
| Characteristics | LAN | MAN | WAN |
| 1) Full form | It stands for local
area network. | It stands for
metropolitan area network. | It stands for wide
area network. |
| 2) Cost | Less Costly | More Costly | Costliest |
| 3) Speed | Upto 10100 Mbps | 5 10 Mbps | 256 Kbps to 2 Mbps |
| 4) Range | 1 Km | Upto 50 Km | entire globe can be connected |
| 5) Topology | Bus and Ring | Distributed Queue
Dual Bus [DQDB] | ATM, Frame Relay,
Sonet |
| 6) Location of computers connected in the system | Computers are located
within the same building. | Computers are
located in the city and are connected using modems or telephone lines so that they can be
easily connected with each other. | Computers are
distributed
all over the country or the continent. The connection is
made via satellite communication link or via internet. |
| 7) Examples | LAN’s example can be
an
office whose different departments such as personnel,
accounting etc. are located in the same building and connected
via bus topology using Ethernet cards. | Example of MAN is
bank whose different branches in a city like Delhi are connected using public
telephone
exchange and the system are connected with each other using
LAN within each branch and different branches are connected
using modem and bridges. | WAN’s example is
the connection of various branches of MNC such as Proctor
& Gamble. These
branches
are linked using microwave satellite communication system or
internet connection. Each branch has its own LAN circuit.
But the different LAN’s in various branches are communicating
with head office using WAN link. |
OSI (Open System Interconnection) Model
The
OSI model is an abstract description for layered
communications and computer network protocol design open system
means that it can communicate with any other system that
follows the specified standards, formats and semantics.
PROTOCOLS give the rules that specify how the different
parties may communicate.
The following are the layers of OSI model:
In
transmission side data flows from layer 7 to layer 1, then
to cabling or suitable medium. When data reaches the reception
side it flows from layer 1 to layer 7.
Application Layer
This layer is the layer for user interaction. We mush have an application software for dealing with the data.
Presentation Layer
It
converts the data into suitable format. It does tasks like
compression, decompression, encryption and decryption.
Session Layer
This layer manages connections between different application layers.
Transport Layer
This
layer converts data into segments and reassembles the data
stream. TCP and UDP are the protocols used in this layer. In
this layer, data is converted into so called segments.
Network Layer
This
layer translates logical address into physical address. This
layer also fixes the route for data path. Router works in
this layer. In this layer data is to called a packet.
DataLink Layer
This
layer provides physical identification of a device using MAC
Address. It adds source and destination address to packets and
convert them into frames.
Physical Layer
This
layer provides the functional requirements for activating a
physical link. In this layer data is carried from one device
to another.
TCP/IP Model (Transmission Control Protocol / Internet Protocol)
Just like the OSI model, the TCP/IP model has many layers:
