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LAN Cabling, Standards, and Topologies

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LAN Cabling, Standards, and Topologies

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Cisco CCNA Study Guide

By Cbrzana

Table Of Contents

LAN Cabling, Standards, and Topologies


Network Topologies

Physical = How the cabling/devices are physically setup

Logical = How the data actually flows

Coaxial = Physical bus/Logical bus

Hub use = Physical Star/Logical bus

Switch use = Physical Star/Logical Star

Token Ring Hub (Multistation Access Unit) = Physical Star/Logical Ring

- > Star also known as hub-and-spoke topology

- > Extended Star is simply an extension of the star topology

- > Full-mesh is every device connected to every other, partial is not 100% connected

  • Frame relays often referred to partial/full mesh due to PVCs

- >Dual rings on Token ring are used for failover/redundancy


Cabling and Connectors


UTP Standards

UTP Category Max Speed Description
1 -- Used for POTS
2 4 Mbps Originally designed for Token Ring.
3 10 Mbps Can be used for telephones.
4 16 Mbps Intended for fast Token Ring speed.
5 1 Gbps Very popular desktop cabling.
5e 1 Gbps Lower emissions, better for Gigabit Ethernet.
6 1 Gbps+ Intended as a replacement for Cat5e, capability to support multigigabit speeds (when standards are created).


UTP = RJ-45 Connectors

Coaxial Cabling: Used for 10Base2 and 10Base5

10Base5 = Thicknet, vampire taps and Attachment Unit Interfaces (AUI) connectors, 500m max length.

10Base2 = Thinnet, BNS connectors with T-connector/transceiver to connect to each machine, 185 meters max


Fiber-Optic Cabling and Connectors for Ethernet

  • Longer distances supported
  • More expensive
  • Secure
  • Less interference than electrical cabling
  • Only type of cabling to support 10 Gigabit Ethernet

- > Dark fiber is when fiber cabling is lease from a service provider


Two Categories of Optical Cabling

Multimode (MM): Use LEDs, shorter distances, less expensive

Singlemode (SM): Use lasers, Small diameter optical fiber, require more precision when being made, more expensive, greater distances.

- > Fiber cabling is made from fiberglass, has extra protection from plastic and Kevlar coating.

- > Light hits the outer wall of the core/inner wall of the cladding, "bounces" until destination reached


Optical Connectors for Ethernet

To transmit data in both directions, need a pair of fiber strands. No need to twist the strands together, since there is no magnetic interference.

ST Connector (BNC style), SC Connector (2 strands attach to single connector), MT-RJ Connector (same plastic mold as RJ-45)


Summary

  Max Length Max Speed Cost Pros Cons
UTP 100m 1 Gbps Low Easy to install, commonly available Susceptible to interference, limited distance
STP 100m 100 Mbps Medium Low emissions, less interference Difficult to work with, limited distance.
Coaxial 500m (Thicknet)

185m (Thinnet)
100 Mbps Medium Least susceptible to interference of all copper media. Single cable problem fails entire network
Fiber 10km+ (SM)

2 km+ (MM)
100 Gbps (SM)

10 Gbps (MM)
High More secure, long distances, highest speeds Difficult to terminate, expensive


Ethernet Cabling Standards

Standard Cabling Maximum Length
10Base5 Thick coaxial 500m
10Base2 Thin coaxial 185m
10Base-T UTP CAT 3,5,5e,6 100m
100Base-FX Two strands, multimode 400m
100Base-T UTP CAT3,5,5e,6, 2-pair 100m
100Base-T4 UTP CAT3,5,5e,6, 4-pair 100m
100Base-TX UTP CAT3,5,5e,6, or STP, 2-pair 100m
1000Base-LX Long-wavelength, MM or SM 10 km (SM)
3 km (MM)
1000Base-SX Short-wavelength, MM 220m with 62.5 micron fiber; 550m with 50-micron fiber
1000Base-ZX Extended wavelength, SM 100km
1000Base-CS STP, 2-pair 25m
1000Base-T UTP CAT5,5e,6 100m


10-Gigabit Ethernet: defined in IEEE 803.ae

  • Allows only point-to-point topology (intended for connectivity between switches)
  • Only full-duplex communication
  • Specifies only optical cabling

IEEE 802.11 Wireless LANs: Known informally as Wi-Fi, only one station can effectively transmit at a time (within the range)

  • 802.11 requires different MAC header than 802.3 header
  • 802.11a = 5 GHz, 54 Mbps
  • 802.11b = 2.4 GHz, 11 Mbps
  • 802.11c = 2.4 GHz, 54 Mbps



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