1. Welcome to Networking and Security! Brett Tjaden 216 ISAT/CS Building Department of Computer Science James Madison University Harrisonburg, VA 22807 Email: tjadenbc@jmu.edu Phone: 540-568-2771 Webpage: https://users.cs.jmu.edu/tjadenbc/Web

2. Introduction “[Internetworking] has become a fundamental part of life.” Internetworking is two things: –Idea: Many heterogeneous networks can be interconnected to function as a coordinated unit –Implementation: A set of open communication conventions (or protocols) have been developed (i.e. TCP/IP)

3. Network Protocols Protocol = syntactic and semantic rules for communication Open = protocol specifications are publicly available –Anyone can implement them Run on lots of different operating systems –Designed to accommodate: Lots of different networking technologies Lots of different applications

4. Internet Services Many popular and widespread application- level Internet services (used by users): –World Wide Web –Electronic mail –File transfer –Remote login –Etc.

5. Internet Services (cont) The Internet’s primary network-level services (used by network programmers): –Connectionless packet delivery Break messages up into small chunks (called packets) Route each packet separately through the network Reassemble message when all packets reach destination –Reliable stream transport Handle problems that can occur such as: –Lost or corrupted packets –Other network errors

6. Distinguishing Features of TCP/IP Many vendors offer proprietary network technologies that offer: –Connectionless packet delivery service –Reliable stream transport service TCP/IP also offers: –Network technology independence –Universal interconnection –End-to-end acknowledgements –Application protocol standards

7. Internetworking – How It Works

8. Protocol Layering Physical Network Layer 1 Layer 2 Layer N Layer 1 Layer 2 Layer N... SenderReceiver

9. Physical Networks An internetwork is typically comprised of many physical networks over which data travels There are many different types of physical networks: –Circuit-switched vs. packet-switched networks –Local Area Networks (LAN) vs. Wide Area Networks (WAN)

10. Circuit-Switched Networks Forms a dedicated connection (circuit) between the two endpoints Examples Advantages Disadvantages

11. Packet-Switched Network Data is divided into packets and each packet is routed through the network separately Examples Advantages Disadvantages

12. Wide Area Networks (WANs) Provide communication over large distances Example Advantages Disadvantages

13. Local Area Networks (LANs) Only spans short distances Examples Advantages Disadvantages

14. Ethernet A popular packet-switched LAN technology invented at Xerox PARC in the 1970’s Components: –The ether –Transceivers –Attachment Unit Interface (AUI) cable –Host Interface

15. Ethernet (cont)

16. Advantages Disadvantages

17. Thinnet A thinner, less expensive, and more flexible alternative to Ethernet Components: –The ether –Computers with transceivers and host interface built in

18. Thinnet (cont)

19. Twisted Pair Very thin, very cheap, very flexible alternative to Ethernet and Thinnet Components: –A hub –Computers with host interface built in

20. Twisted Pair (cont)

21. Summary Internetworking enables many heterogeneous networks can be interconnected to function as a coordinated whole An internetwork is typically comprised of many physical networks over which data travels A popular physical network technology is Ethernet