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


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   

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  oMAN
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
1) Full formIt  stands  for  local
area  network.
It  stands  for
metropolitan    area  network.
It  stands  for  wide
area  network.
2) CostLess  CostlyMore  CostlyCostliest
3) SpeedUpto  10­100  Mbps5­  10  Mbps256  Kbps  to  2  Mbps
4) Range1  KmUpto  50  Kmentire globe can be connected
5) TopologyBus  and  RingDistributed  Queue
Dual  Bus  [DQDB]
ATM,  Frame  Relay,
6) Location  of computers  connected  in  the  systemComputers  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) ExamplesLAN’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: