1 Computer Networks and Communications [Δίκτυα Υπολογιστών και Επικοινωνίες] Lectures 8&9: Internet Protocols in Detail – TCP/IP Univ. of the Aegean Financial and Management Engineering Dpt Petros KAVASSALIS

2 What you will learn in this course A set of fundamental concepts for understanding Data Networks and the Internet A set of fundamental concepts for understanding Data Networks and the Internet  What is the Internet?  Internet architecture and layers  Internet applications and services  New concepts in the evolution of the Internet  The Internet goes Wireless… Familiarization with the structure and organization of Digital Networks Familiarization with the structure and organization of Digital Networks  Business and Social Networks  Electronic Markets and Online Feedback Mechanisms

3 Who am I? PhD in Economics and Management (Univ. Paris Dauphine & Ecole polytechnique) PhD in Economics and Management (Univ. Paris Dauphine & Ecole polytechnique) Research experience Research experience  Ecole polytechnique, Paris  MIT Center of Technology Policy and Industrial Development, MIT CTPID (MIT Internet Telecommunications Convergence Consortium) Current positions Current positions  Univ. of the Aegean (FME): Assoc. Professor  RACTI: Director of ATLANTIS Group

4 Communication tools pkavassalis [at] atlantis-group.gr pkavassalis [at] atlantis-group.gr Course web site: see fme website Course web site: see fme website

5 Course Textbook [ z64SJRBAC&dq=tanenbaum+networks&printsec=frontcover&source=bn&hl=el&ei=ml- dSfH9L4S2jAeJ5L3ZBQ&sa=X&oi=book_result&resnum=4&ct=result]

Supplementary Texts & References William Stallings, Computer Networking with Internet Protocols, Prentice Hall, 2004 William Stallings, Computer Networking with Internet Protocols, Prentice Hall, 2004 William Stallings, Computer Networking with Internet Protocols, Prentice Hall, 2004 William Stallings, Computer Networking with Internet Protocols, Prentice Hall, 2004 James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley, 2008 James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley, 2008 James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley, 2008 James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley,

7 Students evaluation Class Participation (20%) Class Participation (20%)+ Assignments (20%) Assignments (20%)+ Final Exam (60%) Final Exam (60%)

Reminder: Overview of the Internet Petros KAVASSALIS 8 The structure of the Internet is roughly hierarchical

Reminder: A network architecture Petros KAVASSALIS 9

Reminder: TCP/IP in practice Petros KAVASSALIS 10

Operation of TCP/IP Petros KAVASSALIS 11

Internet Transport Layer Common layer shared by all applications Common layer shared by all applications Provides reliable delivery of data Provides reliable delivery of data In same order as sent In same order as sent Commonly uses TCP Commonly uses TCP  Example: Web browsing Uses also UDP (for real-time traffic) Uses also UDP (for real-time traffic) Petros KAVASSALIS 12

Internet Transport Layer key role Provide logical communication between app processes running on different hosts Provide logical communication between app processes running on different hosts Transport protocols run in end systems Transport protocols run in end systems  Send side: breaks app messages into segments, passes to network layer  Receive side: reassembles segments into messages, passes to app layer Two mail transport protocol available to apps Two mail transport protocol available to apps  Internet: TCP and UDP Petros KAVASSALIS 13

Internet Transport Layer Protocols Reliable, in-order delivery (TCP) Reliable, in-order delivery (TCP)  Congestion control  Flow control  Connection setup Unreliable, unordered delivery: UDP Unreliable, unordered delivery: UDP  No-frills extension of “best- effort” IP Services not available: Services not available:  Delay guarantees  Bandwidth guarantees Petros KAVASSALIS 14

TCP header Petros KAVASSALIS 15

UDP header Petros KAVASSALIS 16

Internet Network Layer Exchange of data between an end system and attached network Exchange of data between an end system and attached network Concerned with issues like : Concerned with issues like :  Destination address provision  Invoking specific services like priority  Access to & routing data across a network link between two attached systems Allows layers above to ignore link specifics Allows layers above to ignore link specifics Petros KAVASSALIS 17

Internet Network Layer key role Transport segment from sending to receiving host Transport segment from sending to receiving host  On sending side encapsulates segments into datagrams  On receiving side, delivers segments to transport layer Network layer protocols in every host, router Network layer protocols in every host, router  Host: Creates datagrams / headers  Router examines header fields in all IP datagrams passing through it Petros KAVASSALIS 18

Internet Network Layer in a nutshell No call setup at network layer No call setup at network layer Routers: no state about end-to-end connections Routers: no state about end-to-end connections  no network-level concept of “connection” Packets forwarded using destination host address Packets forwarded using destination host address  packets between same source-dest pair may take different paths Petros KAVASSALIS 19 application transport network data link physical application transport network data link physical 1. Send data 2. Receive data

Internet Network Layer functionality Forwarding Forwarding  Move packets from router’s input to appropriate router output Routing Routing  Determine route taken by packets from source to destination Petros KAVASSALIS 20

Addressing requirements Two levels of addressing required Two levels of addressing required Each host on a subnet needs a unique global network address Each host on a subnet needs a unique global network address  IP address Each application on a (multi-tasking) host needs a unique address within the host Each application on a (multi-tasking) host needs a unique address within the host  Port Petros KAVASSALIS 21

IP header Petros KAVASSALIS 22

IPv6 header Petros KAVASSALIS 23