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Networking Basics CCNA 1 Chapter 5

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Title: Networking Basics CCNA 1 Chapter 5


1
Networking Basics CCNA 1 Chapter 5
2
Cabling LANs
  • Line Styles for Cables Used in Network Diagrams

3
Cabling LANs
  • Ethernet LAN Physical Layer
  • Earliest Ethernet standards used coaxial cabling
  • Todays standards called for twisted-pair
    (usually UTP) or fiber-optic cabling
  • IEEE separated Ethernet into two standards
  • IEEE 802.2 - Logical Link Control (LLC) sublayer
    defines part of the OSI data link layer
  • IEEE 802.3 Media Access Control (MAC) sublayer
    also defines part of the OSI data link layer

4
Cabling LANs
  • Ethernet LAN Physical Layer (continued)

5
Cabling LANs
  • Ethernet LAN Physical Layer Design Considerations
  • Does maximum cable length allowed meet segment
    requirements
  • Cost of cable
  • Cost of equipment on ends of cable
  • Which cables support which Ethernet speeds
  • Ease of installation
  • Susceptibility to interference

6
Cabling LANs
  • Choosing Ethernet Types (Speeds) in the Campus
  • Network engineers must consider speed of Ethernet
    types
  • Most current PCs have 10/100 Mbps NICs means a
    current design would use 100 Mbps Ethernet on the
    LAN
  • Most new PCs come with 10/100/1000 Mbps NICs
    must consider expense of upgrading LAN switches
    to 1000 Mbps (1 Gbps)

7
Cabling LANs
  • Three Types of Ethernet Links
  • End-user level Links between a hub/switch and
    end users computers
  • Workgroup level Links between the hub/switch
    that attach to end users computers and other
    hubs/switches in the LAN core
  • Backbone level Links between the hubs/switches
    in the LAN core

8
Cabling LANs
  • Campus LAN with Online Curriculums LAN Level
    Terms

9
Cabling LANs
  • Ethernet Types and Speeds Used on Various Link
    Types per Online Curriculum

10
Cabling LANs
  • Ethernet Types and Speeds Used on Various Link
    Types Best Practices
  • End-user level 100 Mbps
  • Workgroup level 1 Gbps
  • LAN Core (Backbone) 1 Gbps or 10 Gbps
  • Remember, speeds will increase as the technology
    evolves

11
Cabling LANs
  • Components of the Campus Design Model
  • Access switches and links end-user devices
    connect to access switches (LAN switches), with
    Ethernet links called access links
  • Distribution switches and uplinks a large
    number of access switches connect to a smaller
    number of distribution switches the links
    between them are called uplinks

12
Cabling LANs
  • Components of the Campus Design Model (continued)
  • Building block a single buildings design with
    access and distribution switches
  • Core switches and links in large campuses, each
    building block is connected to very fast core
    switches, using core links

13
Cabling LANs
  • Ethernet Types, Media and Segment Lengths

14
Cabling LANs
  • Ethernet Types, Media and Segment Lengths
    (continued)

15
Cabling LANs
  • Ethernet Types, Media and Segment Lengths
  • Using the charts is important to the LAN planning
    process
  • Most paths between devices are not straight line
  • After media are selected, cables with appropriate
    connectors must be ordered or made
  • Some older NICs and networking devices use
    attachment user interface (AUI) connectors

16
Cabling LANs
  • Common LAN Cable Connectors

17
Cabling LANs
  • Picking UTP Cable Pinouts
  • Straight-through use TIA/EIA-T568-A or
    TIA/EIA-T568-B on both ends
  • Crossover (10BASE-T and 100BASE-TX) - use
    TIA/EIA-T568-A on one end and TIA/EIA-T568-B on
    the other end
  • Crossover (1000BASE-TX) use TIA/EIA-T568-A on
    one end and swap the orange/green (pairs 1 and 2)
    and blue/brown pairs (pairs 3 and 4) on the other
    end

18
Cabling LANs
  • TIA/EIA-T568-A and TIA/EIA-T568B Pinouts

19
Cabling LANs
  • 10BASE-T and 100BASE-TX Crossover Cable

20
Cabling LANs
  • 1000BASE-T Crossover Cable

21
Cabling LANs
  • Crossover Cables
  • Many products, including Cisco switches, us Auto
    Medium-independent Crossover (Auto-mdix)
  • Detects when a cable with wrong pinouts is
    connected
  • Automatically makes internal changes to make
    connection work

22
Cabling LANs
  • Choosing When to Use Straight-Through and
    Crossover Cables
  • Devices that transmit at pins 1 and 2 PCs,
    routers, servers, wireless access points
    Ethernet ports
  • Devices that transmit at pins 3 and 6 hubs,
    switches, bridges, repeaters

23
Cabling LANs
  • Choosing When to Use Straight-Through and
    Crossover Cables
  • Use a straight-through cable to connect
  • Switch to router
  • Switch to PC or server
  • Hub to PC or server

24
Cabling LANs
  • Choosing When to Use Straight-Through and
    Crossover Cables
  • Use a crossover cable to connect
  • Switch to switch
  • Switch to hub
  • Hub to hub
  • Router to router
  • PC to PC
  • Router to PC

25
Cabling LANs
  • Choosing When to Use Straight-Through and
    Crossover Cables
  • Cisco prints an X on ports that transmit on
    pins 3 and 6 instead of pins 1 and 2
  • This denotes they are internally crossed over

26
Cabling LANs
  • Choosing When to Use Straight-Through and
    Crossover Cables

27
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Must play close attention to distances between
    devices
  • Must consider how extending the length of the
    network by adding devices has an impact

28
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Repeaters
  • Extend the distances over which an Ethernet
    network can send data
  • Receives a degraded signal, cleans it up and
    retimes it, and sends it out the other port
  • Cannot indefinitely extend a LAN

29
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Repeaters
  • 5-4-3 rule
  • At most 5 cables in the LAN
  • At most 4 repeaters
  • At most 3 cables can have PCs attached
  • Allows for maximum distance of 500 meters

30
Cabling LANs
  • Basic Function of a Repeater

31
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Hubs
  • IEEE created 10BASE-T and hubs to overcome
    problems with older Ethernet standards
  • Old standard called for a physical bus topology
  • New standard allows a physical star topology
  • Thinner cable makes installation easier
  • Maximum single cable length of 100 m, versus 185
    m and 500 m

32
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Hubs (continued)
  • 10BASE-T allows the use of hubs and repeaters
  • Similar to repeaters, hubs receive a signal on
    one port, regenerate it, and send it out all
    other ports
  • Hubs contain multiple RJ-45 jacks to provide a
    place to connect multiple UTP cables, which
    creates the physical star topology
  • Hubs are sometimes called multiport repeaters
    or concentrators

33
Cabling LANs
  • 10BASE-T with Hub Operation

34
Cabling LANs
  • Comparing the Three Types of Ethernet Hubs

35
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Bridges
  • Use logic to decide whether to forward frames
  • This logic is closely matched to OSI Layer 2, so
    bridges are considered to be Layer 2 devices
  • Bridges use this process
  • Examine incoming frame, look at destination MAC
    address
  • If destination MAC is reachable via a different
    interface than the one one which it was received,
    regenerate and forward out that interface
    (forward)
  • If destination MAC is on the same interface it
    arrived on, discard the frame (filter)

36
Cabling LANs
  • Bridge Making a Filtering Decision

37
Cabling LANs
  • Bridge Making a Forwarding Decision

38
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Ethernet switches
  • Provide all the benefits of repeaters, hubs and
    bridges
  • Most LANs use switches instead of hubs or bridges
  • LANs need repeaters only when very long runs are
    needed

39
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Functions of an Ethernet Switch
  • Like a hub, provides a large number of ports for
    making a physical star topology
  • Like repeaters, hubs and bridges, regenerates a
    clean signal
  • Like bridges, uses filtering/forwarding logic
  • Like bridges, separates a LAN into multiple
    collision domains, increasing LAN bandwidth
  • Beyond the functions of hubs, repeaters, and
    bridges, offers advanced features such as virtual
    LANS (VLANs) and much faster performance

40
Cabling LANs
  • Switch Making a Forwarding Decision

41
Cabling LANs
  • Connecting Ethernet Networking Devices
  • Functions of an Ethernet Switch (continued)
  • Uses a switching table much the same way a bridge
    uses a bridging table - Cisco switching table is
    sometimes referred to as Content Addressable
    Memory (CAM) table
  • Allows devices to send data at the same time
    without collisions by using full-duplex logic

42
Cabling LANs
  • Switch with Four 100 Mbps Ports 400 Mbps

43
Cabling LANs
  • Wireless Communications and Wireless Access
    Points
  • Wireless does not mean just WLANs or Wi-Fi
  • Includes most every type of electromagnetic (EM)
    energy
  • Radio waves
  • Microwaves
  • Infrared light

44
Cabling LANs
  • Wireless Communications and Wireless Access
    Points
  • Infrared (IR) and radio frequencies (RF) are both
    popular for wireless communication today
  • IR requires line-of-sight between sending and
    receiving devices (TV remote control and TV)

45
Cabling LANs
  • Wireless Communications and Wireless Access
    Points
  • RF has been used for communications for more than
    a century AM/FM radio, Airplane to control
    tower, Police and fire departments
  • Does not require line-of-sight
  • Wireless devices designed for two-way
    communication need a transmitter and a receiver
  • WLAN standards use a range of frequencies called
    a spread spectrum

46
Cabling LANs
  • WLAN Review
  • Wireless Access Points (APs)
  • Have much in common with hubs and switches
  • Provide a centralized connection point (without
    wires)
  • Have limitations on distance
  • Like hubs, create a shared medium
  • PCs and laptops use wireless cards, so no
    networking cables are needed
  • The AP connects to the rest of the network with a
    cable

47
Cabling LANs
  • AP, Switch, and Hub Used for End-User Device
    Access

48
Cabling LANs
  • Ethernet NICs
  • NICs expansion PC cards that create a way for
    the PC to connect to a network
  • Must operate and OSI Layers 1 and 2
  • Layer 1 send and receive signals over an
    attached cable
  • Layer 2 they frame data inside a header and
    trailer, with header including Layer 2 address
    called the Media Access Control (MAC) address

49
Cabling LANs
  • Ethernet NICs
  • Network diagrams do not usually show the NIC as
    it is assumed each PC has one
  • On laptops, the NIC might be built in or in a
    small expansion slot called a PC card slot

50
Cabling LANs
  • Ethernet NIC Circuit Board Internal to the PC

51
Cabling LANs
  • Ethernet NIC External Portion with RJ-45
    Connector

52
Cabling LANs
  • Ethernet NICs
  • Most NICs use an RJ-45 connector
  • Older NICs can be replaced or an adapter can be
    used (older routers, e.g., may need an AUI
    connector for their Ethernet ports
  • The use of an AUI means the device does not need
    to have an internal transceiver

53
Cabling LANs
  • Using the LAN Models for PC Communication
  • Computers on a network need to share information
  • Client/server model
  • Client uses some resource on another computer
  • Server provides that service

54
Cabling LANs
  • Using the LAN Models for PC Communication
  • Peer-to-peer model
  • A computer acts as a peer with other computers by
    acting as a client in some cases and a server in
    other cases

55
Cabling LANs
  • Using the LAN Models for PC Communication
  • Peer-to-peer networking
  • Computers act as equals, providing services to
    each other
  • To act as a server, a computer must decide to
    share some or all of its resources with other
    peers

56
Cabling LANs
  • PC Constellation Shares a Folder

57
Cabling LANs
  • Another PC Shares Constellations Folder

58
Cabling LANs
  • Using the LAN Models for PC Communication
  • Peer-to-peer networking
  • Have several advantages over client/server
    networks
  • Simple to install
  • No special hardware required
  • Users control their own resources
  • No network administrator required

59
Cabling LANs
  • Using the LAN Models for PC Communication
  • Peer-to-peer networking
  • Have several disadvantages compared to
    client/server networks
  • Lack centralized security controls
  • Individuals must perform own backups
  • When users PC is acting as a server, performance
    may suffer
  • Dont work well with lots of users (limit of 10
    or so)

60
Cabling LANs
  • Using the LAN Models for PC Communication
  • Client/server networking
  • End users all act as clients
  • Dedicated computers, called servers, provide all
    services
  • Use of multiple servers is common

61
Cabling LANs
  • Client/Server Networking Model

62
Cabling LANs
  • Using the LAN Models for PC Communication
  • Client/server networking
  • End user PCs are typically less expensive
  • Servers use a network operating system (NOS) that
    is more expensive
  • Servers are more expensive and powerful
  • Centralized security is available
  • Centralized backups can be done

63
Cabling LANs
  • Comparing Peer-to-Peer and Client Server
    Networking

64
Cabling WANs
  • Simple Internetwork with Two Routers

Jagged line is a WAN link often called a
lightning bolt
65
Cabling WANs
  • WAN Physical and Data Link Layers
  • Routers can have both LAN and WAN interfaces
  • LAN interface requirements are more obvious
  • RJ-45 jack needs a cable with an RJ-45 connector
  • Some WAN interfaces are less obvious
  • Might be ISDN, DSL or cable

66
Cabling WANs
  • WAN Physical and Data Link Layers
  • Router Serial Interfaces
  • A serial interface connects to channel service
    unit/data service unit (CSU/DSU) with a serial
    cable
  • The proper serial cable must be selected by the
    network engineer
  • Router has WAN interface cards that have
    particular types of connectors

67
Cabling WANs
  • Different Connectors on Router WAN Interface Cards

68
Cabling WANs
  • WAN Link with Serial Cables, CSU/DSUs, and the
    Telco Shown

69
Cabling WANs
  • Routers and WAN Cables
  • Many WAN links require a CSU/DSU
  • Connection to the CSU/DSU from router is with a
    serial cable
  • Different CSU/DSU vendors use different cables
  • After selecting the CSU/DSU, order the correct
    serial cable

70
Cabling WANs
  • WAN Serial Cables Used with a Router

71
Cabling WANs
  • Routers and WAN Cables
  • The CSU/DSU connects to a cable provided by the
    Telco usually an RJ-45 connector but with a
    different pinout
  • Most companies standardize on connectors
  • Some routers have the CSU/DSU built in, so no
    serial cable is needed
  • Network engineer must also consider what protocol
    is being used

72
Cabling WANs
  • OSI Layers 1 and 2 for Router Serial Links

73
Cabling WANs
  • Cable, DSL and ISDN
  • ISDN
  • Allows a WAN connection to be dialed like a phone
    call
  • WAN link is not up and working all the time
  • Often used as a backup to a full-time, always-on
    link

74
Cabling WANs
  • Cable, DSL and ISDN
  • Several varieties of ISDN
  • Basic Rate Interface uses already-installed phone
    lines
  • Allows two concurrent 64 Kbps WAN links called B
    channels
  • Has a signaling channel, the D channel

75
Cabling WANs
  • Cable, DSL and ISDN
  • DSL and cable modems are now popular
  • DSL uses phone lines
  • Cable modems use cable TV coaxial cable
  • All three methods use a variation of
    Point-to-Point Protocol (PPP)

76
Cabling WANs
  • ISDN, DSL and Cable Cables and Connectors

77
Cabling WANs
  • WAN Speeds
  • WAN links provided by Telcos can run at a large
    variety of speeds
  • 2400 bps to multiples of 64 Kbps, up to 1.544
    Mbps (a T1 connection)
  • Traditional WAN speeds go above T1
  • A T3 circuit runs at 28 times the speed of a T1
  • Synchronous Optical Network (SONET) can exceed 10
    Gbps
  • Faster links cost more money
  • Maximum length between devices is based in part
    on speed

78
Cabling WANs
  • Serial Cable Lengths in Comparison to Speed

79
Cabling WANs
  • Choosing DCE and DTE Cables
  • Devices on both ends of a link must be
    synchronized
  • The telco provides clocking (synchronization)
  • The CSU/DSU monitors the clocking from the telco
  • Data communications equipment (DCE) - a device
    that supplies clocking to another device
  • Data terminal equipment (DTE) a device that
    receives clocking from another device and adjusts
    its clock as needed

80
Cabling WANs
  • DCE and DTE on a Typical WAN Link

81
Cabling WANs
  • Choosing DCE and DTE Cables
  • In some cases, the router needs to operate as a
    DCE device
  • This is common in lab situations like ours
  • We do this so we do not have to buy two CSU/DSUs.

82
Cabling WANs
  • Router as DCE Back-to-Back Serial Communication

The connection between the two routers is a
crossover serial connection.
83
Cabling WANs
  • Fixed and Modular Routers
  • Cisco routers with permanently installed
    interfaces are called fixed-function routers

84
Cabling WANs
  • Fixed and Modular Routers
  • Cisco routers with the capability to add and
    remove cards are called modular routers
  • Most current Cisco routers support at least some
    modular interfaces
  • Each interface type has a unique number

85
Cabling WANs
  • Cisco 1841 Modular Router

86
Cabling WANs
  • Cisco 1841 Modular Router

87
Cabling WANs
  • Router Console Cabling
  • Technically isnt a LAN or WAN cable
  • To gain access to a Cisco switch or router for
    initial configuration, you need to know about
    console ports and cables
  • To configure or troubleshoot a Cisco router or
    switch
  • Connect a PC to the console port of the router or
    switch by using a rollover cable
  • Configure a terminal emulator on the PC with the
    proper settings
  • Log into the router or switch by using the
    terminal emulator on the PC

88
Cabling WANs
  • Console Cabling

89
Cabling WANs
  • Router Console Cabling
  • Many PCs have a nine-pin connector (DB-9) which
    is used for serial communications
  • May be called a serial port or a COM port
  • Most routers and switches have an RJ-45 port for
    a console port
  • Connect a PC to a router or switch using a
    rollover cable and two RJ-45 connectors
  • Use an RJ-45 to DB-9 adapter on the PC end

90
Cabling WANs
  • Router Console Cabling
  • Configure HyperTerminal or another terminal
    emulator
  • 9600 bps
  • 8 data bits
  • No parity
  • 1 stop bit
  • No flow control

91
Cabling WANs
  • Router Auxiliary Port
  • Routers also have an auxiliary port
  • Used for out of band (not through the network)
    management
  • A modem may be connected to the auxiliary port
  • The network engineer may call the router and make
    changes and troubleshoot problems over the phone
    line

92
Summary
  • Ethernet is the most widely used LAN technology
  • Ethernet technologies provide a variety of speeds
    from 10 Mbps to 10 Gbps
  • A NICs connector must match the media
  • Coax typically uses BNC connectors
  • STP and UTP use RJ-45 connectors
  • Fiber-Optic uses ST, SC or MT-RJ connectors

93
Summary
  • Twisted-pair cabling must use the correct pinout
    to work properly
  • A crossover cable is used to connect two similar
    devices, such as switches
  • A straight-through cable connects two different
    devices, such as a PC and a switch
  • A rollover cable connects a PC to the console
    port of a router or a switch

94
Summary
  • Repeaters regenerate and retime network signals
    and let them travel a longer distance
  • Hubs act as multiport repeaters and provide a
    central device to connect devices in a star
    physical topology
  • Hubs are sometimes called concentrators
  • Bridges and switches use logic at Layer 2 of the
    OSI model to decide when to forward frames or
    when not to forward (filter) them

95
Summary
  • Bridges and switches examine the destination MAC
    address of the frame and compare it to a list of
    MAC addresses and ports
  • Because bridges and switches do not forward
    traffic unless necessary, they provide more
    bandwidth than hubs and repeaters and greatly
    improve network performance
  • LAN switches provide the same basic functions as
    a bridge, but have a large number of ports that
    act as a concentration point

96
Summary
  • Todays switches are so much faster than bridges
    that vendors such as Cisco no longer sell bridges
  • Switches support a large variety of extra
    features, such as VLANs
  • Wireless networks can be created with much less
    cabling than other networks
  • Wireless APs connect to the rest of the network
    with an Ethernet cable

97
Summary
  • Wireless devices use transmitters and receivers
    to convert bits to EM waves (transmitter) and
    then back to bits at the destination (receiver)
  • Two most common types of wireless technologies
    used for networking are IR and RF
  • Typically computers use a peer-to-peer or
    client/server network model
  • In both models, one computer acts as a client and
    another acts as a server

98
Summary
  • In peer-to-peer networks, networked computers act
    as equal partners
  • In client/server networks, network services are
    located on a computer called a server and
    end-user computers always act as clients
  • Routers are responsible for routing packets from
    source to destination computers
  • Routers typically connect to a wide range of
    networking media, including different WAN (ISDN,
    DSL, CABLE) and LAN (Ethernet) types

99
Summary
  • Each WAN type requires some type of media and
    connector
  • When a routers serial interface is used, the
    cable type is determined by
  • Physical connector on the router
  • Physical interface on the CSU/DSU
  • Router interface can be DCE or DTE, but is
    usually a DTE interface

100
Summary
  • A router serial WAN link can be DCE or DTE
  • DCE provides clock synchronization DTE adjusts
    its clock to match DTE end
  • Traditionally, a router is a DTE device and a
    CSU/DSU is a DCE device (except in lab situations
    where no CSU/DSUs are used)
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