Internetworking. from the Webopedia Computer Dictionary

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1 Internetworking The art and science of connecting individual local-area networks (LANs) to create wide-area networks (WANs), and connecting WANs to form even larger WANs. Internetworking can be extremely complex because it generally involves connecting networks that use different protocols. Internetworking is accomplished with routers, bridges, and gateways. from the Webopedia Computer Dictionary

2 Outline About this course Scope People Organisation Examination Literature Internetworking - Introduction 2

3 Course scope A course about the protocols that are the fundaments of the Internet. The TCP/IP Protocol Suite 3

4 People involved in the course Peter Johansson, Teacher Robert Forchheimer, Examiner 4

5 Course organisation Lectures Classes Examination Written exam Home assignment (report + presentation) Web page: Timeline Guidelines for the report Old exams Lecture slides Course list Reading guide 5

6 Home Assignment Find partners, you work in groups of 3-4 Send an to No later than August 30! Work with the problem and produce Written report Oral presentation, ~15 min 6

7 Literature TCP/IP Protocol Suite, Third Edition by Behrouz A. Forouzan Additional material (RFC's and articles) will be distributed during the course Possible book alternatives might be: (Note! If you use one of these, check where that book differs from the one above!) Computer Networking - A Top Down Approach Featuring the Internet, Second Edition by James F. Kurose and Keith W. Ross, ISBN (paperback) TCP/IP Illustrated, Volume 1 - The Protocols by W. Richard Stevens, ISBN (hardcover) Computer Networks, Fourth Edition by Andrew S. Tanenbaum. ISBN (paperback) 7

8 Lecture 1: Introduction Literature: Forouzan: ch 1-3 RFC2026 (handout) 2004 Image Coding Group, Linköpings Universitet

9 Lecture 1: Outline Internetworking basics Protocols Standards The Internet 9

10 Internetworking basics Connecting two computers - creating a link Connecting many computers - creating networks Connecting networks - creating internetworks 10

11 Creating a link To be able to send information between two computers we need: Equipment for sending and receiving signals Rules for how the signals should be interpreted Rules for how information should be transformed into signals Rules for starting and ending a transmission etc 11

12 Creating a network Connect three or more hosts - a network To be able to communicate in a network we need: a way to distinguish between hosts - addresses. rules for how to start transmission, handle collisions etc Many technologies can be used, e.g. star, ring and bus topologies. Local Area Networks: e.g. Ethernet,Token ring, Wireless, ATM Wide Area Networks - a mesh of point to point links 12

13 LAN Communication Figure from Forouzan 13

14 Creating an internetwork An internetwork is created by connecting two or more networks so that hosts in one network can communicate with hosts in another network. Need a gateway if the communication protocols differ, eg connect an ethernet LAN with a token ring LAN. Need a way to distinguish between networks - addresses again. Need more rules... 14

15 Internet Communication Figure from Forouzan 15

16 Internetworking equipment A LAN can be extended by the use of repeaters, hubs, bridges, (two-layer) switches Two LANs can be connected by the use of routers, (three-layer) switches Figure from Forouzan 16

17 Example Figure from Forouzan 17

18 Protocols A protocol is a set of rules that govern data communication Key elements of a protocol Syntax Semantics Timing Protocols are often designed in a layered architecture 18

19 Standards Agreed-upon rules De facto De jure Standards Organisations ISO ITU-T IEEE etc. 19

20 The OSI-model An ISO standard covering all aspects of network communications Figure from Forouzan 20

21 OSI Model Exchange Figure from Forouzan 21

22 OSI vs TCP/IP Figure from Forouzan 22

23 Addresses Figure from Forouzan 23

24 The Internet History Administration Standards 24

25 History World War II first computers 1960's Mainframe computers late 60's ARPANET, NCP 1973 Paper on TCP 1977 first internet late 70's TCP ---> TCP/IP 1980's The Internet collection of networks communicating using the TCP/IP protocols 25

26 Number of internet hosts The number of internet hosts have grown exponentially since measurements started in early 1980's hosts July million hosts Current growth rate: ~30% per year Note: The addressing system in IPv4 only supports approx million addresses 26

A network of networks The Internet consists of a tiered hierarchy of Internet Service Providers (ISPs) Tier -1 ISPs constitute the Internet Backbone Tier -2 ISPs connect to Tier - 1 ISPs and to

27 A network of networks The Internet consists of a tiered hierarchy of Internet Service Providers (ISPs) Tier -1 ISPs constitute the Internet Backbone Tier -2 ISPs connect to Tier - 1 ISPs and to other Tier - 2 ISPs Tier - 3 ISPs connect to Tier -2 ISPs and to other Tier - 3 ISPs Connection between ISPs take place at a Point of Precense (POP) or a Network Access Point (NAP) Figure from Forouzan 27

28 Administrative Organisation Internet Society (ISOC) Provides support for the Internet standards process Internet Architecture Board (IAB) Technical advisor to the ISOC and to research members of the Internet community Internet Engineering Task Force (IETF) A forum of working groups responsible for operational problems and for reviewing proposed standards. Internet Research Task Force (IRTF) A forum of working groups focusing on long-term research related to the Internet Internet Assigned Numbers Authority (IANA) Previously responsible for management of names and addresses Internet Corporation for Assigned Names and Numbers (ICANN) Responsible for the management of Internet names and addresses. (Overtook this responsibility from the IANA in 1998) 28

29 Internet Administration Figure from Forouzan 29

30 Internet Standards (RFC 2026) The IETF is responsible for the process of creating and adopting new standards. A standard can be a Technical Specification (TS) Applicability Statement (AS) Standards-related publications: Internet-Drafts Request for Comment (RFC) (4946 RFC:s as of August 23, 2007) 30

31 Requirement Levels (RFC2026) An AS shall apply one of the following levels to each of the TSs to which it refers: Required Recommended Elective Limited use Not recommended 31

32 Standardisation process (RFC 2026) The IESG (part of IETF) decides when a specification has reached enough maturity. It is then entered into the standards track : Proposed Standard Draft Standard Internet Standard Historic The specifications are published as RFC's Other RFC classifications: Experimental, Informational 32

33 Maturity levels of an RFC Figure from Forouzan 33

Internetworking. from the Webopedia Computer Dictionary

Internetworking. from the Webopedia Computer Dictionary Internetworking The art and science of connecting individual local-area networks (LANs) to create wide-area networks (WANs), and connecting WANs to form even larger WANs. Internetworking can be extremely