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Networking Media Chapter 1 All Material Taken from Faster Smarter Network+ Certification by Melissa Craft Topologies Physical Topologies Point-to-point connections Multipoint connections Logical Topologies How does the data flow? Physical Star Topology

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networking media

Networking Media

Chapter 1

All Material Taken from Faster Smarter Network+ Certification by Melissa Craft

topologies
Topologies
  • Physical Topologies
    • Point-to-point connections
    • Multipoint connections
  • Logical Topologies
    • How does the data flow?
physical star topology
Physical Star Topology
  • A central hub connects to each device
  • Central hub can also be a switch, multipoint repeater, or Multi-station Access Unit (MAU or MSAU)
  • Most common topology
physical bus topology
Physical Bus Topology
  • Single cable used to connect multiple devices with termination at both ends
physical mesh topology
Physical Mesh Topology
  • All devices are connected to each other

Full mesh topology

hierarchical mesh topology
Hierarchical Mesh Topology
  • Devices are not connected directly to every other device, but a connection path can be made.
physical ring topology
Physical Ring Topology
  • Closed loop of cabling connecting each device in a ring.
  • Data can flow in either direction, depending on configuration.
wireless topology
Wireless Topology
  • Areas capable of transmitting data arranged in cells
  • Access points are used
logical ring topology
Logical Ring Topology
  • Physically a star, but data flows in one direction, thus creating a circular path for data
cellular topology
Cellular Topology
  • Basically a logical bus topology
  • Devices can seamlessly move between cells
  • See P. 16 in text
accessing the media
Accessing the Media
  • Contention
    • CSMA/CD
    • CSMA/CA
csma cd
CSMA/CD
  • Carrier Sense Multiple Access/Collision Detection
  • Walking in without ringing the bell!
  • Just make sure the door is open, even if someone else is in the doorway.
  • When a collision occurs, each sending device must resend the message.
csma cd cont
CSMA/CD (cont.)
  • Advantages
    • Easy to implement
    • Requires few resources
    • Very fast when traffic is light
  • Disadvantages
    • Speed can decrease significantly in high traffic
    • Only detects collisions…doesn’t avoid them
    • All data is treated equally
csma ca
CSMA/CA
  • Carrier Sense Multiple Access/Collision Avoidance
  • Ring the bell before entering!
  • If someone is in the doorway, wait for them to get out of the way.
  • Uses special contention protocols and time slices
csma ca cont
CSMA/CA (cont.)
  • Advantages
    • Less administrative overhead than CSMA/CD
    • Allows more messages to be seemingly sent simultaneously by using time slices
    • Significantly reduces collisions, increases data throughput
  • Disadvantages
    • Collisions still occur
    • All data still treated equally
token passing
Token Passing
  • If you don’t have it, you can’t get in!
  • A special data packet (token) is passed around the network
  • Only the device which has the token can transfer data
token passing cont
Token Passing (cont.)
  • Advantages
    • No data collisions!
    • Highest amount of data throughput in high traffic networks
    • Utilizes demand priority (not all data is treated equally)
token passing cont18
Token Passing (cont.)
  • Disadvantages
    • Much more expensive to implement
    • Requires more processing power to deal with the token
    • Each device must be aware of its neighboring devices so that the token can be received & passed along
    • Low data throughput in low traffic networks
    • Low priority data can have trouble being sent
media types
Media Types
  • Unshielded Twisted Pair (UTP)
    • Uses twisted pairs of wires
    • Subject to crosstalk
    • See table on p. 21
  • Shielded Twisted Pair (STP)
    • Heavy outer covering (shield)
    • Much more resistant to noise
    • More expensive
    • Difficult to install due to lack of flexibility
coaxial cable
Coaxial Cable
  • Standard Cable TV cable
  • Copper conductor surrounded by insulation
  • Braided or mesh outer cover surrounds the insulation (also a conductor)
  • PVC plastic jacket encases cover
thicknet rg 8
ThickNet (RG-8)
  • Older type of coaxial cable
  • Physical bus topology
  • Very thick shielding
  • Difficult to work with because it is so rigid
  • 50 ohm terminators at both ends of bus
  • Uses vampire tap connectors
thinnet rg 58
ThinNet (RG-58)
  • Much more flexible than ThickNet
  • Physical bus
  • Maximum of 30 devices on 185 meter length of cable
  • BNC connectors are crimped onto the cable for connectivity
  • Terminators at both ends
fiber optic cable
Fiber Optic Cable
  • Thin strand of glass enclosed in a glass tube
  • Shielded with PVC plastic
  • Very brittle, not very flexible
  • Immune to crosstalk
  • Supports very long distances
  • Requires specialized installation
  • More expensive option
wireless media
Wireless Media
  • IEEE 802.11 specification
  • Radio frequency (RF) 2.4 gigahertz range for wireless data transmissions
  • Data rate depends upon type of protocol implemented. (802.11-B, 802.11-G)
  • No cables, easy to install & configure
  • Poor security
  • Distance can be limited
media connectors
Media Connectors
  • RJ-11
    • Common telephone connector
  • RJ-45
    • Most common network connection type
    • Looks like a “fat” telephone connector
media connectors26
Media Connectors
  • AUI (Attachment Unit Interface)
    • Used in ThickNet and ThinNet cables
    • 15 pins on the end that connects to the network interface card. (NIC)
    • Other end connects to a short cable which connects to a transceiver, which connects to the main cable.

Transceiver

AUI

media connectors27
Media Connectors
  • BNC (British Naval Connectors)
    • Used in ThinNet 10Base2 Ethernet
    • Resemble cable TV connectors
media connectors28
Media Connectors
  • ST
    • Used in duplex fiber optic connections
media connectors29
Media Connectors
  • SC
    • Used in simplex fiber optic connections
media connectors30
Media Connectors
  • RS-232
    • 9 or 25 pins connectors
    • Used only in serial communications with analog modems
ieee specifications
IEEE Specifications
  • 802.2 (LLC)
    • Logical Link Control
    • Protocol Specification used by all 802 standards
ieee specifications32
IEEE Specifications
  • 802.3 (Ethernet)
    • 10BaseT
    • 10Base2
    • 10Base5
ieee specifications33
IEEE Specifications
  • 802.3u (Fast Ethernet)
    • 100BaseT
ieee specifications34
IEEE Specifications
  • 802.4
    • Token Bus
  • 802.5
    • Token Ring
ieee specifications35
IEEE Specifications
  • 802.6
    • Metropolitan Area Networks (MAN) based on bidirectional fiber optic bus
ieee specifications36
IEEE Specifications
  • 802.11(a & b)
    • Wireless networks
slide37
FDDI
  • Fiber Distributed Data Interface
  • Dual ring topology (uses token passing)
  • If one ring fails, the other takes over
  • Good for long distances
  • Large data capacity