Network Topology And Network Design

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CCNA Guide to Cisco Networking

• Network Topology And Network Design

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Physical Topologies (Star Topology)
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Physical Topologies (continued)

• Star topology
• Star topology advantages
• Break in one cable does not affect other devices
  (except up links)
• Easy to locate problems
• Easy to install
• Does not require termination like bus topology
• Star topology disadvantages
• Center of star topology device (hub) can be
  expensive
• Hub failure can affect entire topology
• Amount of cable is expensive

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Physical Topologies (Ring Topology)

• Ring topology
• FDDI Used in WANs
• Ring topology advantages
• Prevents network collisions
• Each station acts like a repeater
• Ring topology disadvantages
• Cable break can affect all devices
• Temporarily shut down network to add a new
  station
• Maintenance and monitoring is difficult

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IEEE 5-4-3 Rule On Topologies
No more than 5 segments of cable and 4 repeaters
can exist between two stations on the network.
Only 3 of the five segment can be populated with
Computers, bridges, or routers. The other two
segments can only interconnect the repeaters
and/or hubs
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IEEE 5-4-3 Rule On Topologies
5 segments of cable 4 repeaters Only 3 of the
five segment can be populated
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IEEE 5-4-3 Rule
Find the rule violation
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Network Architecture

• IEEE 802
• Logical Link Control (IEEE 802.2)
• CSMA/CD (802.3)
• Token Ring (802.5)
• Wireless Technologies (802.11)
• FDDI Fiber distributed Data Interface (802.5)

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Network Architecture (continued)
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Media

• Twisted-Pair cabling have the following in common
• Copper based data transmission
• Copper wires come in pairs
• Each Wire of a pair is twisted around each other
• Copper wires are enclosed in a sheath
• All wire pairs are enclosed in a sheath

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Media (continued)

• Unshielded twisted-pair (UTP)
• Advantages of UTP cable
• Thin and flexible
• Easy to install
• Many modern buildings come with CAT 5 installed
• Small size does not fill up wiring ducts fast
• Inexpensive per foot
• Disadvantages of UTP cable
• Susceptible to interference
• Cable length is 100 meters or 328 feet
• Register Jacks (RJ)
• RJ-45

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Media (continued)
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Media (continued)

• Shielded twisted-pair (STP)
• Advantages of STP cable
• Greater protection from interference
• Thin and flexible
• Overall it is easy to install
• Disadvantages of STP cable
• Inexpensive per foot but more expensive than UTP
• STP must be grounded, problems exists if not
  grounded properly
• More difficult to install than UTP
• Small size but does fill up wiring ducts faster
  than UTP

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Media (continued)

• Coaxial cabling (Thicknet and Thinnet)
• Advantages of coaxial cabling
• Cable lengths are longer than UTP/STP
• Less susceptible to interference than UTP
• Hubs are not required, direct connection
• Disadvantages of coaxial cabling
• Thicknet is very difficult to install
• More expensive than UTP
• Difficult to troubleshoot

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Media (continued)
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Media (continued)
Thicknet is thicker than Thinnet Thinnet is
limited to 185 meters while Thicknet runs up to
500 meters
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Media (continued)

• Thinnet and Thicknet Connectors
• RG-58 cabling
• BNC
• Attachment unit interface (AUI)
• Barrel connectors
• T-connectors
• Terminators

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Media (continued)
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Media (continued)

• Fiber-Optic cable
• Advantages of fiber-optic cabling
• Transmit data over long distances
• Not susceptible to EMI
• High transmission rates
• Not susceptible to eavesdropping
• Small cable size
• Disadvantages of fiber-optic cabling
• Expensive (not anymore!)
• Cable can be easily damaged during install making
  installations more difficult
• Manual termination of ends is time consuming

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Media (continued)
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Media (continued)
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Media (continued)
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Horizontal Cabling Standards

• Twisted-pair or fiber-optic connections between
  wiring closets
• Electronic Industries Alliance and
  Telecommunications Industry Association (EIA/TIA)
• EIA/TIA-568
• UTP horizontal cable run max 90 meters
• Horizontal cross connect max 6 meters
• Workstation to horizontal drop max 3 meters

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Horizontal Cabling Standards (continued)
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Wiring Closets

• Wiring closets terminates cables to patch panels
  and connect to hubs, Switches, and routers
• EIA/TIA-568 and EIA/TIA-569 terminations
  standards for wiring closets (one per floor)
• Catchment area If a given floor area exceeds
  1000 m2 or horizontal cable exceeds 90 m ,
  additional closets are needed.
• Main distribution facility (MDF)
• Intermediate distribution facility (IDF)

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Wiring Closets (continued)

• Proximity to the POP MDF should be as close as
  possible to the POP (Point of Presence)
• Backbone
• Sometimes called vertical cabling
• EIA/TIA-568 specifies four different cables for
  backbone installations
• 100-ohm UTP
• 150-ohm STP
• 62.5/125-micron optical fiber
• Single mode optical fiber

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Wiring Closets (continued)
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Wiring Closets (continued)
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Performance Considerations

• Connection speeds
• Throughput
• Utilization
• Video or audio streaming/teleconferencing
• Client/server applications
• Host/terminal applications
• Routing protocols
• Routine maintenance tasks
• Broadcast traffic
• Ethernet collisions

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Performance Considerations (continued)

• Solutions for reducing network utilization
• Segment network with switch, bridge, or router
• Reduce the number of services provided on the
  network
• Reduce the number of protocols on the network
• Control access to bandwidth intensive
  applications or protocols

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Performance Considerations (continued)

• Calculating bandwidth and throughput
• Transmission Time file size/bandwidth
• (T Fs/Bw)
• Throughput file size/download time
• (Tp Fs/Dt)
• Collisions and contention
• Use a Protocol analyzer to investigate collision
  rates above 5
• Resource placement users and resources, when
  possible, should be placed on the same segments

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Performance Considerations (Resource Placement)
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Installing Telecommunications Connectors
(continued)
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Installing Telecommunications Connectors (Jack
Wiring)
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Patch Panel (Rear View)
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Patch Panel (Front Panel)
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LAN Design Models

• Two basic design strategies
• Mesh (flat i.e.less structured than Hierarchical)
• Hierarchical
• Three-layer network model
• Core
• Distribution
• Access layer
• Two-layer network model
• One-layer network model

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LAN Design Models (Mesh)
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LAN Design Models (Three- Layer Model)
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LAN Design Models (continued)
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LAN Design Models (continued)