Transcript mcrz.de
NETWORK FUNDAMENTALS NETWORK FUNDAMENTALS ➲ Network Topology ➲ Network Cable ➲ OSI Model ➲ Network Hardware Network topology ➲ Bus Topology ➲ Ring Topology ➲ Star Topology ➲ Tree Topology ➲ Mash Topology Bus Topologie ➲ ➲ ➲ Uses a common backbone to connect all the network devices A single cable(backbone) operates as the shared communication medium for all the connected devices For example: 10Base2 10Base5 Backbone Bus Topology ➲ Advantages ➲ computers can be detached without effect other computers its cheap only a single cable is used Disadvantages if the backbone Cable is broken, the entire network go down all the traffic is send to every station bad performance if more then 15 computers are added to the network It is slower then other topologies Cable must be terminated Ring Topology ➲ ➲ ➲ ➲ each Computer connects to exactly two other Computers all the communication messages travel in the same direction (clockwise, anti clockwise) each node handle every packet example: Token Ring Ring Topology ➲ Advantages ➲ no kollision in the network all stations work as repeater Large networks possible Disadvantages if one computer or cable fails the network will breakdown hard to Implement Expensive components Star Topology ➲ ➲ ➲ one of the most common computer network topologies all computers are connected with a point to point connection to a central device examples: telephone networks, modern ethernet Networks Central Device (Switch,Hub) Star Topology ➲ Advantages ➲ if a cable is broken only the computer wich is connected to the cable can no longer communicate with the network if a computer fails then the other computers are not affected easy extensible high transmission rate Disadvantages if the central device fails the whole network will brakdown Network size is limited by the number of ports on the central device Tree Topology ➲ ➲ ➲ central 'root' node is connected to one or more other nodes that are one level lower in the hierarchy (second level) each second level node will also have one or more other nodes connected to it the nodes are connected via a point to point link Second level node Root node Tree Topology ➲ Advantages ➲ if a computer fails then the other computers are not affected Disadvantages if a node fails all computer wich are connected to the node are no longer reachable If the rootnode fails the whole network is down Mash Topology ➲ ➲ ➲ Every computer will be connected to one ore more other computers. If every computer is connected to every other computer, the network will be called “complete meshed network“ Example: internet, big networks Complete mashed network Mash Topology ➲ Advantages ➲ Is the best topology, because it is the most secured one if one computer faill the communication is still possible because the data will be redirected Disadvantages very hard to install much cable is necessary expensive Network Cable ➲ Thicknet (Yellow Cable) ➲ BNC (cheapernet) ➲ Twisted Pair Thicknet (Yellow Cable) ➲ ➲ ➲ ➲ ➲ ➲ ➲ ➲ is a RG-8/U coaxial cable It is used in 10Base5 networks Yellow Cable to connect a network device a mau is needed the cable ends must be terminated maximum length is 500 metres transmission speed is 10Mbit/s maximum count of computer is 100 Expensive MAU Medium Attachment unit Thinet (cheapernet) ➲ ➲ ➲ ➲ ➲ ➲ ➲ is a RG-58 coaxial cable It is used in 10Base2 networks the cable ends must be terminated maximum length is 185 metres transmission speed is 10Mbit/s maximum count of computer is 30 Network devices is connected using a t-connecter Terminator T-Connector Coaxial Cable structure Twisted Pair ➲ ➲ ➲ ➲ ➲ ➲ It is used in modern networks Maximum length is 100Metre Transmission speed is 10-10000Mbit/s There are serveral Standards for this cable called Categories (Cat-5,Cat-6) A typical cable contains 4 pairs A pair consist of 2 twisted conductors Plastic Jacket Pair Twisted Pair Standards Category Cat 1 Cat 2 Cat 3 Cat 4 Cat 5 Cat 5e Cat 6 Cat 6a Cat 7 Cat 8 Used for Analog speech transmission Token ring,isdn Ethernet Token ring Ethernet Ethernet Ethernet Ethernet Ethernet Video transmission,Ethernet Speed 4 Mbit/s 10 Mbit/s 16-20Mbit/s 100Mbit/s 100-1000Mbit/s 1000Mbit/s 10000Mbit/s 10000Mbit/s ???? Frequnecy 16Mhz 20Mhz 100Mhz 100Mhz 250Mhz 500Mhz 600MHz 1500Mhz OSI Model ➲ ➲ ➲ ➲ Is a abbrevation of Open System Interconnection model defines a networking framework for implementing protocols in seven layers The upper layer represents software that implements network services like encryotion The lower layer implements hardwareoriented functions like routing, addressing, Lower layer Upper Layer OSI Model Layer Function Layer 7: Application Layer Network process Layer 6: Presentation Layer Data representation and encryption Layer 5: Session Layer controls the connections between computers Layer 4: Transport Layer End-to-end connections and reliability Layer 3: Network Layer Path determination and logical addressing Layer 2: Data Link Layer Physical addressing Layer 1: Physical Layer Signal transmission Nezwork Hardware ➲ Hub ➲ Switch Hub ➲ ➲ ➲ ➲ work on layer 1 of the OSI model Do not read any of the data passing trough them Broadcast the recivied packets to all network devices 3 types of hubs passive Hubs con only send and recieve packets active Hubs are passive hubs wich amplify the signals Intelligent Hubs add extra functions like monitoring to an active hub Switch ➲ ➲ ➲ ➲ do the same as hubs but have more intelligence Can read the data packets to determine the source and destination address The packets will only send to the device which have the same destination adress as the packet 2 types pf switches ➲ Unmanaged switches: have no configuration interface,no monitoring and are cheap Managed switches: have a configuration interface and provide functions like monitoring Switch work on serveral Layer Switch Type Layer 1 switch Layer 2 switch Layer 3 switch Layer 4 switch Layer 7 switch Description A simple hub Most common switches switch with router functionality with firewall, vpn functionality With proxy functionality