Index

1. TCP/IP

• many excellent references on TCP/IP
  • Internetworking with TCP/IP: principles, protocols and architecture by Douglas Comer †
  • UNIX Network Programming by Richard Stevens, chapter 4
• topic naturally falls into two parts
  • IP - Internet Protocol
  • TCP - Transmission Control Protocol
• TCP/IP was specifically designed for the Internet

2. History of TCP/IP and Internet

• part of the excitement about the Internet is its size and growth rate

  

3. History of TCP/IP and Internet (continued)

• DARPA was the main funding agency for packet-switched research in the USA DOD
  • began working on the Internet in the mid 1970s
  • design a protocol that would recover if various nodes disappeared
  • DOD had in mind a nuclear war!
  • wanted a nervous system to carry all military information in USA
• by 1980 TCP/IP protocol had been designed
• the physical network was called the ARPANET which consisted of
  • point to point connections
  • packet switching over radio networks
  • satellite communication channels

4. History of TCP/IP and Internet

• January 1983 DARPA demanded that all computer attach to ARPANET via TCP/IP
  • TCP/IP implementations were available at low cost
  • most (90%) Computer Science departments were running BSD Unix
  • TCP/IP available in source form for BSD systems
• growth
  • 1987 Internet growing at 15% per month (Comer p.6)
  • soon after that it began to double each year!

5. History of TCP/IP

• some reasons why
  • reference implementation of TCP/IP in BSD Unix (1983) 4.3 BSD and 4.4 BSD
  • inexpensive microprocessors (1983)
  • inexpensive wide area fiber optic cable - carrying a high throughput of data (1984)
  • deployment of DNS (Domain Name System) (dynamic ASCII to number lookup system)

6. Internet for the masses

• in early 1990’s Tim Berner’s Lee was working at CERN and as a bye product of high energy physics was working on document management system
• he created a hypertext markup language which was to become HTML
• HTTP is the protocol which WWW clients and servers obey
• people mistakenly think the HTTP is the Internet

7. Introduction to TCP/IP

• LANs have developed greatly over the last 20 years
  • there are a large variety of LANs
  • different LANs in different departments and countries
  • equipment can be bought on an incremental basis
  • evolution not revolution - cost savings
• can be really effective if applications can talk to one another across the different LANs
  • companies with different departments can share resources
• one solution is for an operating system to provide this multivendor integration
  • alternatively a standard network protocol could be designed
• Internet Protocol (IP) - so called because it allows communication between LANs

8. Problems/benefits of TCP/IP

• what problems exist if we want to link up many LANs?
  • unique addressing
  • hardware independent
• what are the benefits of the Internet?
  • email
  • file transfer - ftp
  • remote login

9. Problems/benefits of TCP/IP

• browsing the web
  • client server computing
  • information sharing across the world
  • an infrastructure available for business and academia to use - in the future it will be as important for commerce as motor ways, airlines are now
  • global village
  • information super highway - Al Gore
  • couple of hours to send download an operating system from one side of the world to another
• security?

10. Security on the Internet

11. Serious business

• AT&T spend $3 billion in 1992 to upgrade its network. Its main priority was to add fiber optic
• Lawrence Livermore labs
  • 8000 Apple Macs
  • 5000 PCs
  • 2000 Unix Workstations
  • Cray & Meiko supercomputers
  • all run TCP/IP
  • moving to bring Fiber Optic to the desktop - Gbps

12. TCP/IP Protocol Overview

13. TCP/IP Protocol Summary

• Internet Prococol
  • provides the packet delivery service for TCP, UDP and ICMP
  • user processes do not normally explicitly generate IP datagrams
• an IP address is a virtual address, it was not constructed with a preconceived piece of hardware in mind
• Address Resolution Protocol
  • maps an Internet address into a hardware address
• Reverse Address Resolution Protocol
  • maps a hardware address into an Internet address.

14. TCP and UDP

• primarily there are two transport protocols used with IP: TCP and UDP
  • remember that IP may provide an unreliable service
• Transmission Control Protocol (TCP)
  • provides a flexible two-way byte stream protocol (byte stream allows addressing within a host - to user, process or service)
  • provides a bidirectional pipe
  • the source and destination address are called a Port
  • TCP is the most popular transport protocol on top of IP
  • it uses sliding window technique to provide a reliable service
  • it uses a three way handshake to establish a connection
  • and a two way handshake to disconnect

15. User Datagram Protocol (UDP)

• is an unreliable datagram protocol and is deliberately simple
  • it does not ensure that packets arrive in order, un duplicated, or even at all!
• it sends discrete datagrams, and delivers messages that arrive to the appropriate Port (same addressing schema as TCP)
  • a port may belong to a user, process or service
  • the standard Internet name service, DNS, uses UDP
  • it can be regarded as multiplexing many users, processes and services through one IP address
• UDP has no standard connection procedure and no disconnect procedure

16. IP technical introduction

• IP centerpiece of the TCP/IP protocol stack. It hides the differences between data link protocols from the transport protocols that the end user applications use
  • can replace old data link technologies with new faster technologies
  • application independent
• IP defines a virtual network address space
  • if you are connected to the Internet then your network has a unique IP address
  • within that network address your machine has a unique host id.
• IP provides a connectionless packet delivery service
  • it routes small messages from one machine to another on the addressed within that message
  • connectionless service routes each packet separately and therefore does not guarantee reliable delivery
  • having connectionless packet delivery as the basis for all Internet services makes it adaptable to a wide range of hardware
  • connectionless packet delivery is often termed datagram

17. IP (continued)

• the IP protocol works as follows:
  • transport layer split up a message into datagrams of <=64k bytes
• transport layer gives a datagram to the IP layer
  • datagram is transmitted through the Internet
  • a hop at a time (gateway to gateway)
  • a datagram maybe divided into smaller units at any hop
• datagram is reassembled at the destination machine
  • original message is constructed
  • delivered to the corresponding transport layer

18. TCP/IP Support Protocols

• are another reason TCP/IPs popularity

• 

19. TCP/IP Protocol Summary

• Transmission Control Protocol
  • connection-oriented protocol
  • reliable, full duplex, byte stream for user processes
• User Data Protocol
  • connectionless protocol for user processes
  • unreliable
• Internet Control Message Protocol
  • handles error and control information between gateways and hosts
  • normally generated by TCP/IP networking software itself, not the user processes

20. TCP/IP Protocol Summary

• Internet Protocol
  • provides the packet delivery service for TCP, UDP and ICMP
  • user processes do not normally explicitly generate IP datagrams
• Address Resolution Protocol maps an Internet address into a hardware address
• Reverse Address Resolution Protocol
  • maps a hardware address into an Internet address.

Index

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