module 4
DESCRIPTION
Module 4. PHYSICAL MEDIA. 7. 6. 5. 4. 3. 2. 1. Physical Media Types Covered. Coaxial Cable Twisted Pair Fiber Optic Cable WAN Cables. Coaxial Cables. 10Base2 (ThinLAN) - 10 Mbps baseband, 2 for 200 (actually 185 meters) - PowerPoint PPT PresentationTRANSCRIPT
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Module 4
PHYSICAL MEDIA
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Physical Media Types Covered
• Coaxial Cable• Twisted Pair• Fiber Optic Cable • WAN Cables
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Coaxial Cables• 10Base2 (ThinLAN) - 10 Mbps baseband, 2 for 200 (actually 185 meters)
• 10Base5 (ThickLAN) - Maximum data transfer speed of 10 Mbps, uses baseband transmission; 500 meters maximum cable length
Baseband transmission is a type of digital data transmission in which each medium (wire) carries only one signal, or channel, at a time. In contrast, Broadband transmission enables a single wire to carry multiple signals simultaneously.
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Coax - 10Base2 (ThinLAN)
• Cable Type - RG-58A/U
• Impedance - 50
• Terminated with 50 terminators
• Connection method - BNC (as opposed to the F connector used for cable TV)
• Grounding - As determined by local electrical code
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Coax - 10Base2 Rules
• Minimum distance between two nodes: 0.5m (1.64 ft)
• Maximum number of nodes / segment: 30
• Maximum segment length: 185m (606.7 ft)
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Coax - 10Base5 (Thick LAN)
• Impedance - 50
• Terminated with 50 terminators
• Connections - ‘N’ type connections to terminate. ‘Vampire’ tap for node connections.
• Grounding - Grounded at one point only.
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Coax - 10Base5 Rules
• Minimum Distance between two nodes: 2.5m
• Maximum number of nodes / segment: 100
• Maximum segment length: 500m
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WARNING
Breaking any of these rules will cause excessive error conditions!
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Twisted Pair Cable
• Cable Type: Low grade telephone cable through to cat.5. (data cables normally cat.3 to cat.5)
• Shielding: Shielded (STP) Unshielded (UTP)
• Connectors: RJ45, Telco, IBM Type 1 connector (genderless), 9 pin.
• Use: 10BaseT, 100BaseTX, 100VG ANYLAN, Token Ring
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Twisted Pair Rules
• Cable must be twisted
• Maximum distance depends on quality of cable, shielding and speed of transmission
• Maximum cable length for Cat3, Cat4 and Cat5 is 100m
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Fiber Optic
• Cable type determined by - diameter of core, diameter of cladding (e.g.. 62.5 /125)
• Light source - Single mode- Laser, Multimode - LED
• Connectors - SC, ST, MIC
• Use - FOIRL, 10BaseFL, FDDI, 100BaseF, Fiber Channel, SONET/SDH (for WAN) Gigabit Ethernet (future)
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FOIRL: Fiber Optic Inter-Repeater Link is a vendor independent standard means for connecting only 2 repeater units based on the IEEE 802.3 fiber optic specification. It is being replaced by 10BaseFL. 10BaseFL segments can be up to 2000 meters.
FDDI: Fiber Distributed Data Interface handles data rates of up to 100Mbps; typical application: used as backbone for campus and wide-area networks. FDDI networks are token-passing networks, using dual-ring topology over fiber-optic transmission media.
Fiber Channel is a technology for serially transmitting data between computer devices at a data rate of up to 1 Gbps.
SONET/SDH: Synchronous Optical Network is an optical fiber-based network standard; handles 51.8Mbps to 2.48Gbps. SDH is its international equivalent.
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Fiber Optic Rules
• Maximum distance determined by type of cable and light source used.
• Need to ensure cable connection is from TX on one device to RX on the other
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Fiber Optic Safety Considerations
• Never look at the output of a fiber optic transmitter
• Do not handle unterminated fiber
• Do not attach connectors to fiber as special skills and tools are required.
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WAN Cables
• Cable Type: Various
• Shielding: Shielded & Unshielded cable
• Connectors: RS232 (‘D’ type 25, 15, 9 pin), X.21, V.35
• Common pairs use: TX/RX, CTS/RTS, Control/Indicate
• Uses: RS232, X.21, V.35
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WAN Cable Rules
Cable Distance + Cable quality = Maximum Speed
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Cable Connectivity
TO PSTN/NETWORK
MODEMPC
TO PSTN/NETWORK
MODEMROUTER
HUBPC
PC
PC
HUB
TWISTED PAIR
LAN CABLE
WAN CABLE
WAN CABLE
Host connection to network device in a LAN environment
End system to network access point (WAN environment)
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Simple RS232 25 pin straight through DTE/DCE
TX RX
RX TX
PIN 2
PIN 3 PIN 3
PIN 2
TO PSTN/NETWORK
DCEDTE
PC
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Logical pinout groupings
DATA
CONTROL
Pinouts used to transferthe data (such as TX/RX)
Pinouts used to control theflow of data such as RTS/CTS(used in DTE/DCE handshaking)
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Use of straight through and cross over cabling
TX RXRX TX
PIN 2
PIN 3 PIN 3
PIN 2
DCEDTE
DTE DTE
PIN 4
PIN 5 PIN 5
PIN 4 CTSRTS
MODEM
PC
RTSCTS
TX TXRX RX
PIN 2
PIN 3 PIN 3
PIN 2
PIN 4
PIN 5 PIN 5
PIN 4 RTSCTS
RTSCTS
NOTE: More pinouts may be required
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Twisted pair cable connectivity in a LAN environment
MDI-XMDI
PC
HUB
LANcard
MDI=Media Dependent Interface
X in MDI-X=Crossed
MDI (for LAN) is equivalent to DTE (for WAN) & MDI-X (for LAN) is equivalent to DCE (for WAN).
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MDI to MDI-X connection
MDI-XMDI
PC
HUB
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2
3
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1
2
3
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Twisted pair cabling
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Use of straight through and cross over cabling
MDI
PC
STRAIGHT
THROUGH
CABLE
MDI-X
HUB
MDI-XMDI
PC HUB
MDI
ROUTER
MDI-X
SWITCH
CROSS
OVER
CABLE
CROSS
OVER
CABLE
STRAIGHT
THROUGH
CABLE
Hubs and Switches are MDI-X devicesHosts and Routers are MDI devices
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Summary
• Media Types- Coaxial Cable- Twisted Pair- Fiber- WAN Cables
• Safety Considerations for Fiber
• Connectivity Conventions- WAN Cables = DTE/DCE- Twisted Pair LAN = MDI/MDI-X