DCN-network

NETWORKS

A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data Generated by other nodes on the network.

• Most networks use distributed processing, in which a task is divided among multiple computers   .Instead  of  one  single  large  machine  being  responsible  for  all  aspects  of  a  process,   separate computers (usually a personal computer or workstation) handle a subset.
• A network must be able to meet a certain number of criteria. The most important of  these are performance, reliability, and security. 

There are two possible types of connections

1-      Point-to-Point- A  point-to-point  connection  provides  a  dedicated  link  between  two  devices.  The entire capacity of the link is reserved for transmission between those two  devices.

Example- remote control and the television's control system.

2-      Multipoint- A multipoint (also called multidrop) connection is one in which more  than two specific devices share a single link.

Categories of Network

Networks  are  categorized  on  the  basis  of  their  size.  The three basic categories of computer networks are:

Local  Area  Networks  (LAN) 

1. Private owned type
2. All the devices that are part of LAN are within a building or multiple building.
3. very high speed .
4.  LAN connection speeds can be 10Mbps or 100Mbps or 1000Mpbs also.
5.  LAN uses Guided Media

Wide Area Network (WAN)

1. public owned type
2. All the devices that are part of MAN are span across buildings or small town.
3. MAN network has lower speed compared to LAN.
4.  MAN connection speeds can be 10Mbps or 100Mbps.
5.  MAN uses Guided Media or Unguided media.

 Metropolitan Area Network (MAN)

1. Public or private owned type
2. All the devices that are part of WAN have no geographical boundaries.
3. WAN speed varies based on geographical location of the servers. WAN connects serveral LANs  
4.  WAN connection speeds can be 10Mbps or 100Mbps.
5. WAN mainly uses Guided Media or Unguided media. Its long distance communications, which may or may not be provided by public packet network.

STANDARDS IN NETWORKING

Standards  provide  guidelines  to  product  manufacturers  and vendors  to  ensure  national  and international interconnectivity.
Data  communications  standards  are  classified  into  two categories:
1.  De facto Standard
o  These are  the  standards  that have  been  traditionally used and mean by fact or by convention
o  These standards are not approved by any organized body but are adopted by widespread use.
2. De jure standard
o  It means by law or by regulation.
o  These  standards  are  legislated  and  approved  by an body that is officially recognized.