1. The Internet 2nd Lecture
21, April, 2010
Baseer Ahmad Baheer

2. What is the Internet
Nuts and Bolts

3. Continued…
The public Internet is a world-wide computer network, i.e., a network that interconnects millions of computing devices throughout the world. Most of these computing devices are traditional desktop PCs, Unix-based workstations, and so called "servers" that store and transmit information such as WWW pages and messages.

4. Continued… nuts and bolts view
Hosts, End systems
PC’s workstations, servers
PDA’s, phones
Running network application programs
WWW

5. Continued… Protocols Protocol Control sending, receiving of messages
E.g., TCP, IP, HTTP, FTP

6. TCP (the Transmission Control Protocol) and IP (the Internet Protocol) are two of the most important protocols in the Internet.

7. Continued…Communication services provided
Connection-Oriented
Handshaking:setup (prepare for) data transfer ahead of time
Reliable, in-order byte stream data transfer
Loss: acknowledgements and retransmissions
Flow control:
Sender won’t overwhelm receiver
Congestion control:
Senders “slow down sending rate” when network congested

8. TCP : Connection Setup Syn: 1 Seq:1690 Request for Conn-Setup
Syn: 1 Seq:2010 Ack: Conn Granted
Syn: 0 Seq:1691 Ack: 2011

9. TCP : Connection Teardown
Fin: 1 Seq: Conn- Teardown
Ack: Seq: 2010
FIN: 1 Ack: Seq: 2010
Seq: Ack: 2011

10. Network layer:logical communication between hosts
Transport layer:logical communication between processes

11. Transport Layer TCP Multiplexing/Demultiplexing

12. Connection Oriented : Demultiplexing

13. Connectionless No handshaking between UDP sender, receiver
Each UDP segment handled independently of others.
Then why UDP?

14. Connectionless: Demultiplexing

15. Popular Internet applications, their application-layer protocols, and their underlying
transport protocols.

16. Any...