INFORMATIONAL

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Network Working Group T. Socolofsky Request for Comments: 1180 C. Kale Spider Systems Limited January 1991 A TCP/IP Tutorial Status of this Memo This RFC is a tutorial on the TCP/IP protocol suite, focusing particularly on the steps in forwarding an IP datagram from source host to destination host through a router. It does not specify an Internet standard. Distribution of this memo is unlimited. Table of Contents 1. Introduction................................................ 1 2. TCP/IP Overview............................................. 2 3. Ethernet.................................................... 8 4. ARP......................................................... 9 5. Internet Protocol........................................... 12 6. User Datagram Protocol...................................... 22 7. Transmission Control Protocol............................... 24 8. Network Applications........................................ 25 9. Other Information........................................... 27 10. References.................................................. 27 11. Relation to other RFCs...................................... 27 12. Security Considerations..................................... 27 13. Authors' Addresses.......................................... 28 1 . Introduction Socolofsky & Kale [Page 1]

RFC 1180 A TCP/IP Tutorial January 1991 2.2 Terminology RFC 1122, section 1.3.3. A driver is software that communicates directly with the network interface hardware. A module is software that communicates with a driver, with network applications, or with another module. The terms driver, module, Ethernet frame, IP packet, UDP datagram, TCP message, and application message are used where appropriate throughout this tutorial. 2.3 Flow of Data Socolofsky & Kale [Page 3]

RFC 1180 A TCP/IP Tutorial January 1991 Socolofsky & Kale [Page 4]

RFC 1180 A TCP/IP Tutorial January 1991 2.4 Two Network Interfaces Socolofsky & Kale [Page 5]

RFC 1180 A TCP/IP Tutorial January 1991 2.5 IP Creates a Single Logical Network Socolofsky & Kale [Page 6]

RFC 1180 A TCP/IP Tutorial January 1991 Socolofsky & Kale [Page 10]

RFC 1180 A TCP/IP Tutorial January 1991 Socolofsky & Kale [Page 14]

RFC 1180 A TCP/IP Tutorial January 1991 5.3 IP Module Routing Rules Socolofsky & Kale [Page 15]

RFC 1180 A TCP/IP Tutorial January 1991 5.6 IP Route Table Socolofsky & Kale [Page 17]

RFC 1180 A TCP/IP Tutorial January 1991 5.7 Direct Routing Details Socolofsky & Kale [Page 18]

RFC 1180 A TCP/IP Tutorial January 1991 Socolofsky & Kale [Page 20]

RFC 1180 A TCP/IP Tutorial January 1991 7 . Transmission Control Protocol Socolofsky & Kale [Page 24]

RFC 1180 A TCP/IP Tutorial January 1991 8.6 X-Window 9 . Other Information 10 . References 1] Comer, D., "Internetworking with TCP/IP Principles, Protocols, and Architecture", Prentice Hall, Englewood Cliffs, New Jersey, U.S.A., 1988. [2] Feinler, E., et al, DDN Protocol Handbook, Volume 2 and 3, DDN Network Information Center, SRI International, 333 Ravenswood Avenue, Room EJ291, Menlow Park, California, U.S.A., 1985. [3] Spider Systems, Ltd., "Packets and Protocols", Spider Systems Ltd., Stanwell Street, Edinburgh, U.K. EH6 5NG, 1990. 11 . Relation to other RFCs 12 . Security Considerations Socolofsky & Kale [Page 27]