Network centric world. Human networks influenced by data networks such as the internet. In this chapter we will: • Describe how networks impact our daily lives. • Describe the role of data networking in the human network. • Identify the key components of any data network. • Identify the opportunities and challenges posed by converged networks. • Describe the characteristics of network architectures: fault tolerance, scalability, quality of service and security. • Install and use IRC clients and a Wiki server. 1.1: Human network is important, we need to be connected as much as we need air, water, food and shelter. Printing press to TV has enhanced human network. Technology and data networks have the ability to change the way humans interact. Note small town recently got access to internet. Do not do lab 1.1.1 but discuss google earth and street view. Discuss instant messaging, blogs and wikis. Instant messaging instant transfer of voice, text and graphics. Blog ability to publish info on certain subject without knowledge of web design. Wiki colaberative site where many people edit and review documentation. wikipedia very popular. discuss podcasting, recordings originally for ipods but put on the net so that many people can listen to them. e-learning allowing people to colaberate and access much more information. advantage of distance courses such as this one. Online courses useful to businesses as it can train employees and reduce travel costs. Intranets are networks only accessible in a company. Extranets allow suppliers to check inventory parts etc. telecomuting is popular as it saves on travel time. Internet also changes the way we play. Online games, social networking etc. 1.2: Before we communicate we need to set rules or protocols. We consider • An identified sender and receiver • Agreed upon method of communicating (face-to-face, telephone, letter, photograph) • Common language and grammar • Speed and timing of delivery • Confirmation or acknowledgement requirements communication quality is important, external influences include: • The quality of the pathway between the sender and the recipient • The number of times the message has to change form • The number of times the message has to be redirected or readdressed • The number of other messages being transmitted simultaneously on the communication network • The amount of time allotted for successful communication Internal factors that affect communication: • The size of the message • The complexity of the message • The importance of the message network as a platform: 4 things in common: • Rules or agreements to govern how the messages are sent, directed, received and interpreted • The messages or units of information that travel from one device to another • A means of interconnecting these devices - a medium that can transport the messages from one device to another • Devices on the network that exchange messages with each other Standards allow equipment from various vendors to communicate with each other. Medium: Can be wired, copper optical fibre or wireless. which can travel in air or space. Copper includes coaxial cable, phone cables, twisted pair. Optical fibre are thin strands of glass that carry light energy. TCP/IP is the protocol suite that carries most network traffic these days. It has routing addressing and error handling mechanisms to ensure messages get to their intended destination. Converged networks: Television, radio, data and telephone networks used to run on their own medium and be implemented separately. Now with network convergance they can all run on shared infrastructure, consider Voice over IP. Network architecture: Network needs 4 things: Fault tollerence, scailability, quality of service and security. Fault tollerence: ability of internet to be available and survive and recover from faults, multiple redundant paths between points on the net. scailability: network can expand to meet expectation of users. various layers of the network design can be upgraded independantly to provide more services to users. Quality of service is important for real time applications such as voice and video this changes the way networks are designed and built. Security of information is a concern and many tools and practices are in place to try maintain this security. difference between circuit switched and packet switched networks. If device fails on circuit switched network then call is dropped needs to be re-established. Packet switched networks more fault tollerant as packets can be re-routed via different nodes to reach destination in case of a fault. Message can be broken into many packets that contain addressing information so that packets can get from source to destination. Packets have sequence number so they can be reassembled at the destination. Packets can use all available network resources circuits are not wasted. telecommunications industry wants to charge users for time volume and resources utilized. Quality of service: If demand for network services exceeds bandwidth then devices can queue packets in memory but this causes delays. If packets are held for too long they can be dropped if there are too many packets to hold. Different types of packets need different handling such as real-time traffic, bulk trafic and interactive traffic. Various qualities like gold silver and bronze. Balance needs of organizations with QOS. Security is important, loss of data, theft of intelectual property, missdirection of funds and lost of business confidence could be a result of bad security practices. Need to physically secure devices to prevent tampering and also need to secure content. insure confidentiality. Maintain data integrity. source integrity data came from sender. Hash algorythms, digital signatures can help with that. Insure availability so that users can do their work. trends: Increase number of mobile users. more network devices, increased range of services.