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Lesson 4 – UNDERSTANDING NETWORK CABLING
Network topologies
Network cabling
Installing and maintaining Network cabling
Selecting and installing a SOHO Network
OVERVIEW
Network topology = Shape of the Network.
It is the most important step in planning a Network.
NETWORK TOPOLOGIES
Bus topology
Star topology
Ring topology
Types of Network topologies
Common Bus Multipoint Topology.
1 cable from one end of the Network to the other.
Devices are connected to the cable at different locations.
Bus topology
Bus topology
Specifications:
Number of nodes in a segment.
Number of segments used through repeaters.
Proximity of nodes to each other.
Length of a segment.
Coax cable required.
Termination of bus ends.
Bus topology
Networks use:
Coaxial cable
BNC T-connectors
Bus topology
Advantages:
Least expensive.
Uses less material.
Needs less installation labor.
Bus topology
Drawbacks:
Failure in a part of the segment causes the entire segment to
fail.
Troubleshooting can take a long time.
Tends to be unreliable.
Bus topology
10Base-2 Ethernet has:
Better performance.
Maximum speed of 10Mbps.
RG-58/AU or RG-58/CU coaxial cable and BNC connectors.
50-ohm terminating connector.
Maximum of 30 nodes per segment.
Maximum segment length of 185 meters (607 feet).
Extended segments through the use of repeaters.
1.5 feet distance between nodes.
Bus topology
A central unit, called a hub or concentrator, hosts a set of network cables that radiate out to each node on the Network.
Star topology
Star topology
Uses either:
10Base-T Ethernet.
100Base-T Ethernet.
Star topology
10Base-T Ethernet:
Requires four wires (two twisted-pairs in a single sheath).
Can be run on Cat 3 or Cat 5 cable.
Is limited to a length of 100 meters.
Is unlimited in the number of nodes in a segment.
Uses RJ-45 connectors.
Star topology
100Base-T Ethernet:
Requires eight actual wires (four twisted-pairs in a single
sheath).
Uses Cat 5 cable or better.
Is limited to a length of 100 meters.
Is unlimited in the number of nodes in a segment.
Uses RJ-45 connectors.
Star topology
Star topology Networks cost more.
In a Star topology, a single Network connection that goes
bad affects only that connection.
Star topology Vs. Bus topology
Rings are a logical arrangement.
The cables are wired in a star, with each node connected on
its own cable to the MAU.
Electrically the Network behaves like a ring.
It is based on Token Ring instead of Ethernet.
Ring topology
Ring topology
Ethernet Networks manage signals through CSMA/CD
(Carrier Sense Multiple Access/with Collision Detection).
Token Ring Networks manage their bandwidth with “token
passing”.
Rings Vs. Stars and Bus:
Basic cable types:
Unshielded twisted-pair (UTP)
Shielded twisted-pair (STP)
Coaxial
Fiber-optic cable
NETWORK CABLING
Unshielded twisted-pair
Similar to UTP, but has a braided metal shield surrounding
the twisted pairs.
The metal shield reduces the chance of interference from
external electrical sources.
Shielded twisted-pair
Coaxial cable
Uses a glass strand and carries data signals as light instead
of electricity.
This cable can easily reach 2 miles at 100Mbps.
Fiber-optic cable
Twisted-pair cabling Network
Twisted-pair cabling Network
An RJ-45 Connection
The RJ-45 jack on a hub is DCE (data communications equipment).
The jack on a computer’s NIC is DTE (data terminal equipment).
Twisted-pair cabling Network
Twisted-pair cabling Network
Communication is not possible between DCE-DCE / DTE-DTE
devices using twisted-pair/RJ-45 cable with the following wiring.
Twisted-pair cabling Network
A crossover cable with the following wiring compensates for this
shortcoming.
Twisted-pair cabling Network
Twisted-pair performance designations.
Twisted-pair cabling Network
Plenum Vs. Non-Plenum cable
Coaxial cable
Most of the cable is the thin variety (RG-58), used with Thin
Ethernet.
Some may use the thicker cable (RG-8) for Thick Ethernet.
Coaxial cable
Thin Ethernet cabling is:
Wired in a bus arrangement.
Uses BNC connectors.
Coaxial cable
INSTALLING AND MAINTAINING NETWORK CABLING
Cable plant installation should include:
Proper cable and connectors.
Complete labeling of all parts.
As-built drawing of cabling routes and locations.
Certification report for installed cables.
Education for bus-type Network users about the coaxial cable.
Choosing a cabling contractor
How will the contractor document the cable plant?
What are his/her documentation standards?
Will s/he provide a set of as-built drawings?
How does the contractor install the cable to avoid electrical
interference sources in the ceiling and walls?
Does the contractor recommend a wiring solution that
combines telecom wiring with data wiring?
Has the contractor done any local installations that you can
view?
Does the contractor provide speedy post-installation
support for new wiring drops?
Choosing a cabling contractor
What equipment does the contractor use to certify the
cable plant?
What certification documentation will the contractor
provide upon completion?
Does the contractor also provide post-installation
troubleshooting services?
Choosing a cabling contractor
Typical problems:
Abnormally slow network performance.
Sporadic disconnections from the Network.
Complete loss of Network connectivity.
Troubleshooting coaxial cable systems is more difficult
because the entire Network is down.
Solving cabling problems
To track unobvious problems:
Use a coaxial cable scanner.
Get an extra terminator for the Network.
Solving cabling problems
The following can be shared:
Printers
High-speed Internet connection
Storage space
Backup devices
SELECTING AND INSTALLING A SOHO NETWORK
Standard Network hardware:
A central hub
Network Interface Card (NIC)
Network cable
Operating System
Selecting a SOHO Network
Phone Line Networks
Power Line Networks
Wireless Networks
Other home Networks
Network topologies:
Bus
Star
Ring
SUMMARY
Network cabling:
Unshielded twisted-pair (UTP)
Shielded twisted-pair (STP)
Coaxial
Fiber-optic cable
Summary
Installing and maintaining Network cabling:
Cable plant installation.
Choosing a cable operator.
Solving cabling problems.
Summary
Selecting a SOHO Network:
Advantages
Standard Network hardware
Other home Networks
Summary
