Post on 03-Jan-2016
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
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)
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
Internet Services
• Many popular and widespread application-level Internet services (used by users):
– World Wide Web– Electronic mail– File transfer– Remote login– Etc.
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
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
Internetworking – How It Works
Protocol Layering
Physical Network
Layer 1
Layer 2
Layer N
Layer 1
Layer 2
Layer N
. . .. . .
Sender Receiver
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)
Circuit-Switched Networks
• Forms a dedicated connection (circuit) between the two endpoints
• Examples
• Advantages
• Disadvantages
Packet-Switched Network
• Data is divided into packets and each packet is routed through the network separately
• Examples
• Advantages
• Disadvantages
Wide Area Networks (WANs)
• Provide communication over large distances
• Example
• Advantages
• Disadvantages
Local Area Networks (LANs)
• Only spans short distances
• Examples
• Advantages
• Disadvantages
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
Ethernet (cont)
Ethernet (cont)
• Advantages
• Disadvantages
Thinnet
• A thinner, less expensive, and more flexible alternative to Ethernet
• Components:– The ether– Computers with transceivers and host interface
built in
Thinnet (cont)
Twisted Pair
• Very thin, very cheap, very flexible alternative to Ethernet and Thinnet
• Components:– A hub– Computers with host interface built in
Twisted Pair (cont)
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