petros kavassalis

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Computer Networks and Communications

[Δίκτυα Υπολογιστών και Επικοινωνίες]Lectures 8&9: Internet Protocols in Detail –

TCP/IPUniv. of the Aegean

Financial and Management Engineering Dpt

Petros KAVASSALIS

<pkavassalis@atlantis-group.gr> 2

What you will learn in this course

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 Business and Social Networks Electronic Markets and Online Feedback Mechanisms

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Who am I?

PhD in Economics and Management (Univ. Paris Dauphine & Ecole polytechnique)

Research experience Ecole polytechnique, Paris MIT Center of Technology Policy and Industrial Development, MIT

CTPID (MIT Internet Telecommunications Convergence Consortium)

Current positions Univ. of the Aegean (FME): Assoc. Professor RACTI: Director of ATLANTIS Group

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Communication tools

e-mail: pkavassalis [at] atlantis-group.gr Course web site: see fme website

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Course Textbook[http://books.google.gr/books?id=Pd-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

James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley, 2008

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Students evaluation

Class Participation (20%)

+ Assignments (20%)

+ Final Exam (60%)

Reminder: Overview of the Internet

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The structure of the Internet is roughly hierarchical

Reminder: A network architecture

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Reminder: TCP/IP in practice

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Operation of TCP/IP

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Internet Transport Layer

Common layer shared by all applications Provides reliable delivery of data In same order as sent Commonly uses TCP

Example: Web browsing Uses also UDP (for real-time traffic)

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Internet Transport Layer key role

Provide logical communication between app processes running on different hosts

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 Internet: TCP and UDP

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applicationtransportnetworkdata linkphysical

applicationtransportnetworkdata linkphysical

logical end-end transport

Internet Transport Layer Protocols

Reliable, in-order delivery (TCP) Congestion control Flow control Connection setup

Unreliable, unordered delivery: UDP No-frills extension of “best-

effort” IP Services not available:

Delay guarantees Bandwidth guarantees

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applicationtransportnetworkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

applicationtransportnetworkdata linkphysical

logical end-end transport

TCP header

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socketdoor

TC Psend buffer

T C Preceive buffer

socketdoor

segm en t

applica tionwrites data

applicationreads da ta

UDP header

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Internet Network Layer

Exchange of data between an end system and attached network

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

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Internet Network Layer key role

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 Host: Creates datagrams

/ headers Router examines header

fields in all IP datagrams passing through it

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Internet Network Layer in a nutshell

No call setup at network layer Routers: no state about end-to-end connections

no network-level concept of “connection” Packets forwarded using destination host address

packets between same source-dest pair may take different paths

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applicationtransportnetworkdata linkphysical

applicationtransportnetworkdata linkphysical

1. Send data 2. Receive data

Internet Network Layer functionality

Forwarding Move packets from

router’s input to appropriate router output

Routing Determine route taken

by packets from source to destination

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applicationtransportnetworkdata linkphysical

applicationtransportnetworkdata linkphysical

networkdata linkphysical network

data linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysical

networkdata linkphysicalnetwork

data linkphysical

Addressing requirements

Two levels of addressing required

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 Port

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IP header

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IPv6 header

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