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
Outline About this course Scope People Organisation Examination Literature Internetworking - Introduction 2
Course scope A course about the protocols that are the fundaments of the Internet. The TCP/IP Protocol Suite 3
People involved in the course Magnus Öberg, Teacher Robert Forchheimer, Examiner Guest Lectures? 4
Course organisation Lectures Classes - two groups Group A - Swedish Group B - English Examination Written exam Assignment (report + presentation) 5
Literature TCP/IP Protocol Suite, Second Edition by Behrouz A. Forouzan, ISBN 0-07-246060-1 (hardcover), ISBN 0-07-119962-4 (paperback) Additional material (RFC's and articles) will be distributed during the course Possible book alternatives might be: (OBS! 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 0-321-17644-8 (paperback) TCP/IP Illustrated, Volume 1 - The Protocols by W. Richard Stevens, ISBN 0-201-63346-9 (hardcover) Computer Networks, Fourth Edition by Andrew S. Tanenbaum. ISBN 0-13-038488-7 (paperback) 6
Lecture 1: Introduction Literature: Forouzan: ch 1-3 2004 Image Coding Group, Linköpings Universitet
Lecture 1: Outline Internetworking basics Protocols Standards The Internet 8
Internetworking basics Connecting two computers - creating a link Connecting many computers - creating networks Connecting networks - creating internetworks 9
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 10
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 technology's can be used, eg mesh, star, ring and bus topologys. Local Area Networks: eg Ethernet,Token ring, Wireless, ATM Wide Area Networks - a mesh of point to point links 11
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. Needs a gateway if the communication protocols differ, eg connect an ethernet LAN with a token ring LAN. Needs a way to distinguish between networks - addresses again. Needs more rules... 12
Internetworking equipment A LAN can be extended by the use of repeaters hubs bridges Two LANs can be connected by the use of routers switches 13
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 14
Standards Agreed-upon rules De facto De jure Standards Organisations ISO ITU-T IEEE etc. 15
The OSI-model An ISO standard covering all aspects of network communications 16
OSI vs TCP/IP OSI - layers 7. Application 6. Presentation 5. Session 4. Transport 3. Network TCP/IP - layers 5. Application 4. Transport 3. Network 2. Data link 1. Physical 2. Data link 1. Physical 17
Addresses Three different type of addresses are used in the TCP/IP protocols: Physical address - identifies a network interface Internet address - a universal address, independent of underlying physical network Port Address - identifies processes 18
The Internet History Administration Standards 19
History WWII first computer 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 20
Number of internet hosts The number of internet hosts have grown exponentially since measurements started in early 1980's. 1981-213 hosts 2003 - more than 200 million hosts Note: The addressing system in IPv4 only supports approx. 4000 million addresses 21
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) 22
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) 23
Internet Standards 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) 24
Standardisation process The IESG 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 25