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Transcript
Unit 27: Principles of Computer Networks Introduction to Networks Network Types BTEC Nat IT Business - Principles of Networking 1 Aims Different types of Networks revised Understand the purpose of a computer network Create network drawings Understand Packets BTEC Nat IT Business - Principles of Networking 2 What is the purpose of a network? Enables file sharing (should cut down on printing costs) Share resources, such as printers, scanners, etc., to get more use out of office equipment (cutting down costs) Share software with multi-user licenses. Perform data backups quicker and easier with files on shared drives. Easier and more manageable Internet connection BTEC Nat IT Business - Principles of Networking 3 Types of Network LAN (Local area network) The definition of a LAN has become increasingly vague over the last ten years. It was understood that it was interconnected computers at one location i.e. college or a workplace. Know due to faster technology LAN devices can be used over longer distances. A LAN can be as small as two computers by using a simple Ethernet connection or can divided into sub networks using switches and routers. BTEC Nat IT Business - Principles of Networking 4 Local Area Network - LAN Single campus Can be multiple networks interconnected No special telecommunications hardware is necessary, as cables/signals never leave the company’s premises Fast data transfer rates reliability of transmission not always top priority damaged data can be re-transmitted easily 5 Task Using Visio try to recreate the LAN shown below. (Feel free to make it your own) BTEC Nat IT Business - Principles of Networking 6 Types of Network WAN (Wide area network) A WAN is a complex network system, comprising of interconnected LANs. WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. WANs are often built using leased lines. A router connects to the LAN on one side and a hub within the WAN on the other Network protocols including TCP/IP deliver transport and addressing functions. BTEC Nat IT Business - Principles of Networking 7 Wide Area Network - WAN The rest of the planet Slower data transfer rates (end to end) reliability is a high priority retransmission of missing data is a large overhead extensive use of external telecommunication systems backbone transfer rate is now faster than LANs! The Internet International telecommunications Satellite systems e.g. Global Positioning System - GPS 8 Several options are available for WAN connectivity: http://en.wikipedia.org/wiki/Wide_area_network BTEC Nat IT Business - Principles of Networking 9 WAN BTEC Nat IT Business - Principles of Networking 10 Janet backbone All UK academic institutions access the internet via the Janet network .ac.uk domain Funded by Joint Information Systems Committee (JISC) In October 2006 SuperJANET5 was launched after £29 million of investment. It provided an upgrade path to 40GBit/s. Most organisations connected by twenty WANs Map from http://www.janet.ac.uk/about/topology/SJ5topology-map.pdf 11 WAN TECHNOLOGIES FRAME RELAY ATM – ASYNCHRONOUS TRANSFER MODE MPLS – MULTI-PROTOCOL LABELLED SWITCHING BTEC Nat IT Business - Principles of Networking 12 FRAME RELAY BTEC Nat IT Business - Principles of Networking PACKET SWITCHING MESH CONNECTIONS CORE OF A WAN Monitors traffic on system – re-routing Directs traffic from system to system Cheap 13 ATM BTEC Nat IT Business - Principles of Networking Data cells smaller than packets Faster Separate voice and data communications Used with Skype Similar functions to Frame Relay 14 MPLS BTEC Nat IT Business - Principles of Networking Most recent successor Cooperates with routing protocols Highly adaptable Adjusts to changes in networks Directs data from one network node to another using short path labels not long network addresses 15 Types of Network MAN (Metropolitan area networks) A Metropolitan Area Network (MAN) is a large computer network that spans a metropolitan area or campus. The network size falls intermediate between LANs and WANs. MANs provide Internet connectivity for LANs in a metropolitan region, and connect them to wider area networks like the Internet. They typically use wireless infrastructure or optical fiber (or fibre) connections to link their sites. A MAN (like a WAN) is not generally owned by a single organisation. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a network service provider who sells the service to the users. BTEC Nat IT Business - Principles of Networking 16 Metropolitan Area Network - MAN Multiple campuses e.g. within a city small geographical area Australians use MANs to interconnect South Eastern cities Slower data transfer rates? need reliability of WANs with speed of LANs 17 VAN – Value Added Networks Hosted sevice Like a regional Post Office Intermediatory between business partners sharing standards or data Transmits data by EDI or as XML Routes, stores & delivers EDI messages EDI – Electronic Data Interchange – transfers electronic documents or business data from one partner system to another BTEC Nat IT Business - Principles of Networking 18 PAN – Personal Area Netork Interconnects devices in an individual person’s workspace Wireless connections – Bluetooth Can connect to a higher level network or Internet Bluetooth – short range radio waves up to 10 metres Computers, cell phones, PDAs, headsets, mouse or other pointing devices BTEC Nat IT Business - Principles of Networking 19 Types of Network Mesh network A netlike communications network in which there are at least two pathways to each node. A fully meshed network means that every node has a direct connection to every other node. Most mesh networks are partially meshed and require traversing nodes to go from each node to every other. BTEC Nat IT Business - Principles of Networking 20 Task Using the internet look into what a packet is. Create a network diagram in Visio to represent “SuperJanet”. BTEC Nat IT Business - Principles of Networking 21 Packet A packet is a formatted unit of data carried by a packet mode computer network. Computer communications links that do not support packets, such as traditional point-to-point telecommunications links, simply transmit data as a series of bytes, characters, or bits alone. When data is formatted into packets, the bitrate of the communication medium can better be shared among users than if the network would have been circuit switched. By using packet switched networking it is also harder to guarantee a lowest possible bitrate. BTEC Nat IT Business - Principles of Networking 22 Conclusion Considered the purpose of a computer network Revised some of the different types of networks Used Visio to create network diagrams Gained an understanding of a Packet BTEC Nat IT Business - Principles of Networking 23