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Hands-on Networking Fundamentals

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Presentation on theme: "Hands-on Networking Fundamentals"— Presentation transcript:

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

2 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 Hands-on Networking Fundamentals

3 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 Hands-on Networking Fundamentals

4 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 Hands-on Networking Fundamentals

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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) Hands-on Networking Fundamentals

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12 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. Hands-on Networking Fundamentals

13 Fiber-Optic Cable 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 Hands-on Networking Fundamentals

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17 Gigabit Ethernet Gigabit Ethernet (1000BaseX) Uses of Gigabit Ethernet
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 Hands-on Networking Fundamentals

18 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 Hands-on Networking Fundamentals

19 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 Hands-on Networking Fundamentals

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

22 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 Hands-on Networking Fundamentals

23 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 Hands-on Networking Fundamentals

24 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 Hands-on Networking Fundamentals

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26 Hub 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 Hands-on Networking Fundamentals

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29 Bridge 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 Hands-on Networking Fundamentals

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31 Bridge (continued) Translational bridge Three primary bridge functions
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 Hands-on Networking Fundamentals

32 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 Hands-on Networking Fundamentals

33 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 Hands-on Networking Fundamentals

34 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 Hands-on Networking Fundamentals

35 Hands-on Networking Fundamentals

36 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 Hands-on Networking Fundamentals

37 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 Hands-on Networking Fundamentals

38 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 Hands-on Networking Fundamentals

39 Switch Dual purpose Bridge-like characteristics of switch
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 Hands-on Networking Fundamentals

40 Gateway Software or hardware interface Functions of a gateway
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 Hands-on Networking Fundamentals

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42 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 Hands-on Networking Fundamentals

43 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 Hands-on Networking Fundamentals

44 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 Hands-on Networking Fundamentals

45 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 Hands-on Networking Fundamentals

46 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 Hands-on Networking Fundamentals

47 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 Hands-on Networking Fundamentals


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