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Hands-on Networking Fundamentals

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Hands-on Networking Fundamentals Chapter 4 Connecting Through a Cabled Network – PowerPoint PPT presentation

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Title: Hands-on Networking Fundamentals


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

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

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

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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
Activity 4-4 Building a UTP Cable
  • Time Required Approximately 2030 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
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

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17
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
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
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
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
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
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
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

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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

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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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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