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Hands-on Networking Fundamentals Chapter 4 Connecting Through a Cabled Network.

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Presentation on theme: "Hands-on Networking Fundamentals Chapter 4 Connecting Through a Cabled Network."— Presentation transcript:

1 Hands-on Networking Fundamentals Chapter 4 Connecting Through a Cabled Network

2 Hands-on Networking Fundamentals2 Communications Media Types OSI Layer 1: communication media and interfaces Five basic communication media types –Coaxial cable: based on copper wire –Twisted-pair cable: based on copper wire –Fiber-optic cable: glass or plastic cable –Hybrid fiber/coax: combines copper and fiber –Wireless technologies: radio or microwaves Suitability of media varies with different networks –Example: uses of coaxial cable Older LANs LANs in areas with signal interference strong Connecting wireless antenna to network device

3 Hands-on Networking Fundamentals3 Communications Media Types (continued) Consider capabilities and limitations of media Factors affecting choice of LAN or WAN medium –Data transfer speed –Use in specific network topologies –Distance requirements –Cable and cable component costs –Additional network equipment that might be required –Flexibility and ease of installation –Immunity to interference from outside sources –Upgrade options –Security

4 Hands-on Networking Fundamentals4 Coaxial Cable Two types of coaxial cable (coax) –Thick: used in early networks, typically as backbone Backbone: cabling between network equipment rooms, floors, and buildings –Thin: used to connect desktops to LANs Has much smaller diameter than thick coax Use of both thick and thin coaxial cables declining

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8 8 Twisted Pair Cable Twisted-pair cable –Contains pairs of insulated copper wires –Outer insulating jacket covers wires Communication specific properties –Copper wires twisted to reduce EMI and RFI –Length: up to 100 meters –Transmission speed: up to 10 Gbps RJ-45 plug-in connector attaches cable to device –Less expensive and more flexible than T-connectors Two kinds of twisted pair cable: shielded and unshielded (preferred)

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12 Hands-on Networking Fundamentals12 Activity 4-4: Building a UTP Cable Time Required: Approximately 20–30 minutes Objective: Experience building a UTP cable. Description: In this activity, you attach 4-pair UTP cable to an RJ-45 connector. You need the cable, a crimper, a connector, and a wire stripper. These instructions and Figure 4-6 follow the EIA/TIA-568- B standard.

13 Hands-on Networking Fundamentals13 Fiber-optic cable –One or more glass or plastic fiber cores encased in glass tube (cladding) –Fiber cores and cladding are surrounded by PVC cover –Signal transmissions consist light (usually infrared) Three commonly used fiber-optic cable sizes –50/125 micron Micron (μm): millionth of a meter 50 represents core diameter 125 represents cladding diameter –62.5/125 micron –100/140 micron Fiber-Optic Cable

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17 Hands-on Networking Fundamentals17 Gigabit Ethernet Gigabit Ethernet (1000BaseX) –Provides data transfer of up to 1 Gbps –Uses CSMA/CD access methods –Upgrade path for 100BaseX Ethernet networks Uses of Gigabit Ethernet –Alternative for backbone LAN congestion –Attract token ring users with star-based topologies Gigabit Ethernet target –Installations using Layer 3 routed communications Separate standards for fiber-optic and twisted-pair cables

18 Hands-on Networking Fundamentals18 The Role of Firmware and NIC Drivers Firmware and NIC driver support communications –Firmware: software stored on a chip, such as ROM –NIC Driver: manages how packets or frames sent Firmware or driver may automatically detect media Some NIC drivers can be signed Driver signing: placing digital signature in driver Functions of digital signature –Ensures driver compatible with operating system –Certifies that driver tested for defects or viruses –Ensures that driver cannot overwrite new driver

19 Hands-on Networking Fundamentals19 Half- and Full-Duplex NIC Communications Two transmission modes for NIC and network equipment –Half-duplex: send and receive, not at the same time –Full-duplex: parallel sending and receiving Made possible by buffering at NIC Buffering: temporarily storing information Full-duplex is a good choice –Usually faster than half-duplex

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21 Hands-on Networking Fundamentals Chapter 5 Devices for Connecting Networks

22 Hands-on Networking Fundamentals22 LAN Transmission Devices Uses of LAN transmission equipment –Connecting devices on a single network –Creating and linking multiple networks or subnetworks –Setting up some enterprise networks Connecting devices that will be discussed –Repeaters, MAUs, hubs, bridges, routers, brouters, switches, gateways

23 Hands-on Networking Fundamentals23 Repeater Connects two or more cable segments Retransmits incoming signal to all other segments Cable segment is run within IEEE specifications – Example: Ethernet segment in star-bus network Performs four Physical layer functions –Filter out signal disturbance caused by EMI and RFI –Amplify and reshape incoming signal –Retime the signal (in Ethernet applications) –Reproduce the signal on all cable runs

24 Hands-on Networking Fundamentals24 Multistation Access Unit Multistation access unit (MAU or MSAU) –Central hub on a token ring network –May have intelligence built-in to detect problems Smart multistation access unit (SMAU) Tasks performed by MAU –Connect nodes in a logical ring upon a physical star –Move the token and frames around the ring –Amplify data signals –Expand token ring network by daisy-chain connections –Provide for orderly movement of data –Shut down ports to malfunctioning nodes

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26 Hands-on Networking Fundamentals26 Central network device connecting nodes in star Functions of a hub –Centrally connect multiple nodes into one network –Permit connections on single or multiple LANs –Provide multi-protocol services –Consolidate the network backbone –Provide connections for several different media types –Enable centralized network management and design Unmanaged hub (simplest) –Logical bus or token ring physically connected as star –May be active or passive Hub

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29 Hands-on Networking Fundamentals29 Network device connecting LAN segments Functions of a bridge –Extend LAN when maximum connection limit reached Example: the 30-node limit on an Ethernet bus –Extend a LAN beyond the length limit Example: beyond 185 meters for thinnet segment – Segment LANs to reduce data traffic bottlenecks – Prevent unauthorized access to a LAN Operates in promiscuous mode –Examine frame's physical destination address –Occurs at MAC sublayer of OSI Data Link layer Bridge

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31 Hands-on Networking Fundamentals31 Bridge (continued) Translational bridge –Converts frame to new access method and media type –Example: from token ring to Ethernet Discards addressing information not used in Ethernet Three primary bridge functions –Learning: learn network topology and device addresses Information stored in a bridging table –Filtering: do not flood certain frames, discard others Enables bridge to used for security purposes –Forwarding: transmit frames to destination Based on data built-in to bridging table Some bridges are used to cascade network segments

32 Hands-on Networking Fundamentals32 Spanning Tree Algorithm Defined by the IEEE 802.1d standard –Bridges frames in networks with more than two bridges –Sets up a system of checks performed by bridges Two motivations for using spanning tree algorithm –Ensure a frame does not enter infinite loop Causes congestion that may intensify to broadcast storm –Forward frames along the most efficient route Efficiency based on distance and utilization of resources Services for frames performed by algorithm –Create one-way path around network (use bridge data) –Establish maximum number of hops for maximum route –Enable bridges to send frames along best route

33 Hands-on Networking Fundamentals33 Router Learns, filters, and forwards like a bridge Differs from a bridge in significant ways –Connect LANs at the Network layer of the OSI model –Add intelligence to bridge capabilities –Receive regular communications from nodes General functions of a router –Reduce traffic by efficiently directing packets –Join neighboring or distant networks –Connect dissimilar networks –Prevent bottlenecks by isolating portions of a network –Secure portions of a network by acting as a firewall

34 Hands-on Networking Fundamentals34 Router (continued) Uses a metric to determine optimal routes Components which may inform metric calculation –Number of incoming packets waiting at a particular router port –Number of hops between sending and receiving segments –Number of packets that can be handled in time frame –Size of the packet (large packet may be subdivided) –Bandwidth (speed) between two communicating nodes –Whether a particular network segment is available May isolate segments to avert congestion

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36 Hands-on Networking Fundamentals36 Static and Dynamic Routing Static routing requires routing tables –Routing tables specify paths between routers –Tables set up and maintained by network administrator Dynamic routing independent of network administrator Functions automatically performed in dynamic routing –Determine which other routers can be reached –Determine shortest paths to other networks with metrics –Determine when path to a router is down or unusable –Use metrics to reconfigure alternative routes –Rediscover router and network path after restoration

37 Hands-on Networking Fundamentals37 Routing Tables and Protocols Routers maintain two important databases –Routing table: contains addresses of other routers –Network status: contains information about traffic, topology, and status of links Databases updated by regular exchange of data Router forwards packet on basis of metrics Routers use one or more protocols –Multiprotocol type: each protocol has address database Two common communication protocols: RIP and OSPF

38 Hands-on Networking Fundamentals38 Routing Tables and Protocols (continued) Routing Information Protocol (RIP) –Determines shortest number of hops to other routers –Information added to each router's table –Disadvantages Updates containing entire routing table create traffic Only uses hop count as a metric Open Shortest Path First (OSPF) protocol –Sends only portion of table related to immediate links –Packages routing information in compact form Local routers: LAN-based –Join LANs; segment traffic; act as firewalls

39 Hands-on Networking Fundamentals39 Switch Dual purpose –To provide bridging capacity –To increase bandwidth Bridge-like characteristics of switch –Operates at Data Link MAC sublayer –Uses table information to filter and forward traffic LAN uses two switching techniques (fabric) –Cut-through: forward portions of frame –Store-and-forward: frame buffered until link available

40 Hands-on Networking Fundamentals40 Gateway Software or hardware interface –Enables two networked or software systems to link Functions of a gateway –Convert common protocols to specialized type –Convert message formats from one format to another –Translate different addressing schemes –Link a host computer to a LAN –Provide terminal emulation for connections to host –Direct electronic mail to the right network destination –Connect networks with different architectures Can function at any OSI layer

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42 Hands-on Networking Fundamentals42 WAN Transmission Devices WAN transmission over two network types –PSTN (public switched telephone networks) –Leased telephone lines such as T-carrier or ISDN Characteristics of WAN transmission equipment –May have analog component or be completely digital –Converts signal for long distance communications –Creates multiple channels in medium (grow bandwidth) Frequently used WAN transmission devices –Telephone modems, ISDN adapters, cable TV modems, DSL modems/routers, access servers, routers

43 Hands-on Networking Fundamentals43 Telephone Modems Modem (modulator/demodulator) –Converts outgoing binary (computer) signal to analog –Converts incoming analog signal to a binary signal Two ways to attach a modem to a computer –Internal: installed in computer using expansion slot –External: attached to serial port connector via cable Three common types of connectors –DB-25 connector, DB-9 connector, USB Modem data transfer rate measured in two ways –Baud rate: number of signal events per second –Bits per second (bps): bits per second

44 Hands-on Networking Fundamentals44 Telephone Modems (continued) Data terminal equipment (DTE) –Device that prepares data for transmission –Data transfer speed of PC is DTE communications rate Data communications equipment (DCE) –Device (modem) that converts data from DTE –Speed of modem is DCE communications rate Modems use two communication formats –Synchronous: continuous data bursts controlled by clock –Asynchronous: discrete signals delimited by start and stop bits

45 Hands-on Networking Fundamentals45 Cable TV Modems Uses two channels to communicate –Upstream: transmit outgoing data, sound, TV signals –Downstream: receive and blend incoming signals Factors affecting transmission speed –Modem speeds may differ upstream and downstream Example: 30 Mbps upstream, 15 Mbps downstream –Maximum bandwidth reduced by other subscribers Cable hub handles maximum of 30 Mbps Cable service may impose policy limits Data Over Cable Service Interface Spec (DOCSIS) –Also called Certified Cable Modem Project –Provides standards and certifications

46 Hands-on Networking Fundamentals46 DSL Modems and Routers Digital Subscriber Line (DSL) –Works over copper wire likes ISDN –Requires intelligent adapter in connecting computer Intelligent adapter: sends digital signal over copper wire Simplex communication over copper wire –Dedicated lines for incoming and outgoing signals Transfer 2.3 Mbps upstream, 52 Mbps downstream Advantages of DSL over cable –Dedicated DSL line more secure –Dedicated DSL provides full bandwidth DSL networks utilize combined DSL adapter/router

47 Hands-on Networking Fundamentals47 Remote Routers Operate over long distances –Connect ATM, ISDN, frame relay, high-speed serial, and X.25 networks –Example: connect networks from NY to LA into WAN Similarities with local routers –Can support multiple protocols –Can be set up as a firewall Most routers connect to WAN through serial interface –CSU/DSU for T-carrier communications Channel service unit (CSU): interface to T-carrier line Data service unit (DSU): digital interface to CSU –Modular adapter for other high-speed connections

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