1. NETWORKING CONCEPTS

2. THE INTERNET When 2 or more n/w are connected they become an internetwork or an internet Eg. Assume an organization has two offices. One has bus topology LAN,other has star topology LAN To control these office by other one we have to connect these three entities and for this we create a backbone WAN. To connect Lan to this we need 3 pt-pt WAN.

3. Hetrogeneous n/w made of 4 WAN and 2 LAN

4. THE INTERNET n/w is a group of connected communicating devices such as computers or printers Internet is more than 100’s and 1000’s of interconnected networks In 1967 ARPA presented a small n/w of connected computers.That is idea of ARPANET In ARPANET the idea is that computers is connected to specialised computer called interface message processor(IMP)

5. THE INTERNET The IMP would connected to other IMP and each IMP would communicate with other IMP and also its own attached host

6. THE INTERNET TODAY Today’s internet is made up of many WAN and LAN joined by connecting devices and switching stations Most end users who want internet connection use services of ISP Service providers can be international ISP,national,local,regional ISP etc

8. THE INTERNET TODAY International ISP Connect nations together National ISP n/ws created and maintained by specialised companies Major internet connection point that serve to tie all ISP’s together is NAP

9. THE INTERNET TODAY Regional ISP Small ISP that are connected to one or more national ISP Local ISP Provide direct service to end users Can connect directly to regional or national ISP It can be a company that just provides internet services,a corporation with a n/w that supplies services to its own employees,or a non profit organzation such as college that runs its own n/w

10. KEY ELEMENTS OF INTERNET

11. Purpose of internet is to connect end systems called hosts Hosts may be pc,server,workstation,mainframe etc Hosts are connected to n/w like Lan,WAN etc n/w are then connected by routers.each router attaches to 2 or more n/ws But some hosts can directly connect to a router rather than through a n/w

12. HOW THE INTERNET OPERATES A host may send data to other host anywhere on internet The source host breaks data to be sent to a sequence of packets called IP datagram or IP Packets Each packet includes a unique numeric address of destination host known as IP address Based on this destination address each packet travels through a series of routersand n/w from source to destination Each router as it receives a packet makes a routing decision and forwards packet along its way to destination

13. INTERNET ARCHTECTURE Key elements of internet are set of hosts A host is a computer Individual hosts and LANs are connected to ISP through point of presence(POP) The connection is started with a customer premises equipment (CPE) CPE is a communication equipmet located onsite with the host For home users this CPE is a modem

14. INTERNET ARCHTECTURE The CPE is physically attached to the local loop ‘local loop’ is the infrastructure between providers installation and site where the host is located

15. INTERNET ARCHTECTURE Eg. A home user with a modem attaches modem to telephone line The telephone line is typically a copper wire that run from house to a central office(CO) owned and operated by a telephone company.in this case local loop is a pair of copper wire running between home and CO In many cases local loop provider is the telephone company and ISP is large service organization But often local loop provider is also the ISP

16. INTERNET ARCHTECTURE ISP provides access to larger n/w through a POP POP is a facility where a customer can connect to ISP n/w This facility is owned by ISP POP can be bank of modem or can be an access server at CO

17. INTERNET TERMINOLOGIES CO: Place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other n/w CPE Telecommunication equipment that is located on the customer premises eg.telephone,modem etc ISP Company that provides other companies or individuals with access to internet

18. INTERNET TERMINOLOGIES NAP Major internet connection point that serve to tie all ISP’s together