1. Institute for Visualization and Perception Research 1 © Copyright 1998 Haim Levkowitz Network Layered Protocols

2. Institute for Visualization and Perception Research 2 © Copyright 1998 Haim Levkowitz Layered protocol models... Protocol message contents... Identities Sender, receiver Message length Message data Layered protocols... Protocol enveloping... OSI reference model... Internet TCP/IP model... Protocol enveloping in TCP/IP...

3. Institute for Visualization and Perception Research 3 © Copyright 1998 Haim Levkowitz Layered protocols... N layers

4. Institute for Visualization and Perception Research 4 © Copyright 1998 Haim Levkowitz Protocol enveloping...

5. Institute for Visualization and Perception Research 5 © Copyright 1998 Haim Levkowitz OSI reference model... Open Systems Interconnection abstract model Does not define: PL bindings, OS bindings, API issues, UI issues Defines: 7 protocol layers...

6. Institute for Visualization and Perception Research 6 © Copyright 1998 Haim Levkowitz Defines: 7 protocol layers... Physical... Data link... Network... Transport... Session... Presentation... Application...

7. Institute for Visualization and Perception Research 7 © Copyright 1998 Haim Levkowitz Physical... Network transmission medium E.g., coaxial, twisted-pair, fiber-optic Raw bit-stream service Responsible only for writing / reading bits to / from physical medium

8. Institute for Visualization and Perception Research 8 © Copyright 1998 Haim Levkowitz Data link... Group bits into frames Goal: reliable delivery mechanism Error detection Noise, interference Collisions Flow control Avoid unnecessary frame loss Saturated buffers

9. Institute for Visualization and Perception Research 9 © Copyright 1998 Haim Levkowitz Network... Extend data link layer From local to neighboring / distant networks E.g., Ethernet, Token Ring Incompatible physical and link layers ==> Internetworks (networks of networks) Topology: routers Two network layer services...

10. Institute for Visualization and Perception Research 10 © Copyright 1998 Haim Levkowitz Two network layer services... connection-oriented (CO) "reliable" / "virtual-circuit" well ordered data stream guarantee lost, order, duplicate connectionless (CL) "unreliable" / "datagram" no guarantees

11. Institute for Visualization and Perception Research 11 © Copyright 1998 Haim Levkowitz Transport... higher-level tasks (not end-to-end delivery) multiplexing OSI: 5 incompatible transport protocols CL, w/ CL network CL, w/ CO network CO, w/ CO network CO, w/ CL network highest network aware

12. Institute for Visualization and Perception Research 12 © Copyright 1998 Haim Levkowitz Session... how data exchanged in dialog two-way simultaneous (full-duplex) two-way alternate (half-duplex) one-way (simplex) checkpointing synch points in data stream resume aborted transfer at last encountered synch point

13. Institute for Visualization and Perception Research 13 © Copyright 1998 Haim Levkowitz Presentation... hide diff in data rep'n e.g., ASCII vs. EBCDIC generic rep’n w/ ISO ASN.) spec...

14. Institute for Visualization and Perception Research 14 © Copyright 1998 Haim Levkowitz Generic rep'n w/ ISO ASN. spec... (Abstract Syntax Notation One) Boolean Integer (arb. length) Real (arb. length & prec.) Enumerated (days of week, months of year, etc.) Bit string (arb. length) Octet (byte) string (arb. length) Null (any undef'd value)

15. Institute for Visualization and Perception Research 15 © Copyright 1998 Haim Levkowitz Application... service consumer via APIs

16. Institute for Visualization and Perception Research 16 © Copyright 1998 Haim Levkowitz Internet TCP/IP model... 5 layers physical, data link, network, transport, application session, presentation by application, w/ assistance of API Network layer: IP... Transport layer: TCP & UDP... Application layer...

17. Institute for Visualization and Perception Research 17 © Copyright 1998 Haim Levkowitz Network layer: IP... move data between endpoints if not on same host ==> routing IP protocol IP datagram (packet)

18. Institute for Visualization and Perception Research 18 © Copyright 1998 Haim Levkowitz Transport layer: TCP & UDP... Transmission Control Protocol (TCP) connection-oriented User Datagram Protocol (UDP) connectionless

19. Institute for Visualization and Perception Research 19 © Copyright 1998 Haim Levkowitz Application layer... FTP SMTP: Simple Mail Transfer Protocol NNTP: Network News HTTP

20. Institute for Visualization and Perception Research 20 © Copyright 1998 Haim Levkowitz Protocol enveloping in TCP/IP... Application data --> TCP segment --> IP datagram -- > Ethernet frame