Chapter 1: Foundation CIS 427 PDF

Chapter 1: Foundation CIS 427 Problems  How to build a scalable network that will support different applications?  What is a computer network?  How is a computer network different from other types of networks?  What is a computer network architecture? CIS 427...

Chapter 1: Foundation CIS 427 Problems  How to build a scalable network that will support different applications?  What is a computer network?  How is a computer network different from other types of networks?  What is a computer network architecture? CIS 427 2 Chapter Outline  Applications  Requirements  Performance  Network Architecture  Implementing Network Software CIS 427 3 Chapter Goal  Exploring the requirements that different applications and different communities place on the computer network  Define key metrics that will be used to evaluate the performance of computer network  Introducing the idea of network architecture  Introducing some key elements in implementing Network Software CIS 427 4 1.1: Applications  Most people know about the Internet (a computer network) through applications  World Wide Web  Email  Online Social Network  Streaming Audio Video  File Sharing  Instant Messaging  Online Gaming  … CIS 427 5 Example of an Application A multimedia application including video-conferencing Application Protocol: World Wide Web  URL  Uniform resource locater  http://www.cs.princeton.edu/~llp/index.html  HTTP  Hyper Text Transfer Protocol  TCP  Transmission Control Protocol  17 messages for one URL request  6 to find the IP (Internet Protocol) address  3 for connection establishment of TCP  4 for HTTP request and acknowledgement  Request: I got your request and I will send the data  Reply: Here is the data you requested; I got the data  4 messages for tearing down TCP connection CIS 427 7 1.2: Requirements  Application Programmer  List the services that his application needs: delay bounded delivery of data  Network Designer  Design a cost-effective network with sharable resources  Network Provider  List the characteristics of a system that is easy to manage CIS 427 8 Connectivity  Need to understand the following terminologies  Scale  Link  Nodes  Point-to-point  Multiple access  Switched Network  Circuit Switched  Packet Switched (a) Point-to-point  Packet, message (b) Multiple access  Store-and-forward  Connectivity  Terminologies (contd.)  Cloud  Hosts (a)  Switches  internetwork  Router/gateway  Host-to-host connectivity  Address  Routing  Unicast/broadcast/ (b) multicast (a) A switched network (b) Interconnection of networks Cost-Effective Resource Sharing  Resource: links and nodes  How to share a link?  Multiplexing  De-multiplexing  Synchronous Time- division Multiplexing  Time slots/data Multiplexing multiple logical transmitted in predetermined slots flows over a single physical link Cost-Effective Resource Sharing  FDM: Frequency Division Multiplexing  Statistical Multiplexing  Data is transmitted based on demand of each flow.  What is a flow?  Packets vs. Messages  FIFO, Round-Robin, Priorities (Quality-of- Service (QoS)) A switch multiplexing packets  Congested? from multiple sources onto  LAN, MAN, WAN one shared link  SAN (System Area Networks Support for Common Services  Logical Channels  Application-to-Application communication path or a pipe Process communicating over an abstract channel  Common Communication Patterns  Client/Server  Two types of communication channel  Request/Reply Channels  Message Stream Channels CIS 427 14  Reliability  Network should hide the errors  Classes of failure: 1. Bits are lost  Bit errors (1 to a 0, and vice versa)  Burst errors – several consecutive errors 2. Packets are lost (Congestion) 3. Links and Node failures  Messages are delayed  Messages are delivered out-of-order  Third parties eavesdrop CIS 427 15