1. Internet
  2. Communication Links : made of physical media coaxial cable, copper wire, fibre optics, radio spectrum. Transmission Link Bandwidth
  3. Routers: Intermediate switching routers.
  4. Packet Switching - multiple communicating end systems to share a path at same time. More efficient than circuit switching, no dedicated path
  5. Circuit switching where data flows in a sequence not in packets (telephone lines), dedicated path, particular bandwidth required, call setup required i,e we need to setup the path.
  6. Topology of Internet : loosely hierarchical,
  7. Private networks are often referred to as intranets


  1. Communication between any two devices have a set of rules

Network Edge

  1. Host / End Systems: They host the application programs and they sit at the edge of the internet. Client and servers together called as the distributed systems. They are also called as the Hosts are of two types:
    1. Clients: desktops pc
    2. Servers: powerful machines
  2. Connectionless and Connection-Oriented Services: Provided by the TCP/IP services.
    1. Connection Oriented: TCP They establish the connection first then sent the data packets. This is called as handshake procedure.Loose connection means only the end-systems are aware of the connection not the packets ie, packet switches contain no connection information.

Reliable data transfer connection: Reliability is achieved through acknowledgements and retransmissions. Flow control to make sure excess packets are not send. State of congestion control when the router get overloaded.

    1. Connectionless: UDP. No handshake. Data gets delivered faster. Source has no idea which all packets arrive at the destination.No services like FLOW Control or Congestion Control.