ch6 installing a physical network
Most switches enable you to use multiple NICs for a single machine, a process called
*bonding* or *link aggregation.*
When deciding on this location, keep five issues in mind:
1. *distance* The telecommunications room must be located in a spot that won't require cable runs longer than 90 meters. 2. *power* If possible, put the telecommunications room on its own dedicated circuit; 3. *humidity* Remember that dryness also means low humidity. Avoid areas with the potential for high humidity, 4. *cooling* Make sure your telecommunications room has an airconditioning outlet or some other method of keeping the room cool. 5. Access (6. expandability )
a cable drop
1. A single run of cable from the telecommunications room to a wall outlet 2. a new run coming through a wall outlet that does not yet have a jack installed.
signal loss/degradation is caused by
1. Broken cable or open connection 2. bad SFP/GBIC 3. dirty connector 4 connector mismatch 5. attenuation 6. Dispersion
crimping an RJ-45 onto a UTP cable.
1. Cut the cable square using RJ-45 crimpers or scissors. 2. Strip off ½ inch of plastic jacket from the end of the cable 3. Slowly and carefully insert each individual wire into the correct location according to either TIA/EIA 568A or B 4. Insert the crimp into the crimper and press
Connecting the cables to patch panels requires you to deal with three issues.
1. patch cable management. organize cables very well or not 2. the overall organization of the patch panel as it relates to the organization of your network. 3. documenting everything clearly and carefully.
1U
1.75-inch space
the TIA/EIA 568 specification allows only UTP cable lengths of
90 meters. Why it's not 100 meters by the rules of 10/100/1000BaseT networks? Because we need to consider the length of the patch cable too.
equipment rack
A metal structure used in equipment rooms to secure network hardware devices and patch panels. Most of them are 19 in wide.Devices designed to fit in this use a height measurement called units, or U.
online UPS
A type of UPS that uses the A/C power from the wall outlet to continuously charge its battery, while providing power to a device through its battery
cable certifier
A very powerful cable testing device used by professional installers to test the electrical characteristics of a cable and then generate a certification report, proving that the cable runs pass TIA/EIA standards.
time domain reflectometer
Advanced cable tester that tests the length of cables and their continuity or discontinuity, and identifies the location of any discontinuity due to a bend, break, unwanted crimp, and so on.
link light
An LED on NICs, hubs, and switches that lights up to show good connection between the devices.
continuity tester
An instrument that tests whether voltage (or light, in the case of fiber-optic cable) issued at one end of a cable can be detected at the opposite end of the cable. Indicates whether the cable will successfully transmit a signal
raceway
Any enclosed channel designed for holding wires and cables.
Which of the following cables should never be used in a structured cabling installation?
Coax
far-end crosstalk
Crosstalk on the opposite end of a cable from the signal's source
temperature monitor
Device for keeping a telecommunications room at an optimal temperature.
collision light
It flickers when it detects collisions on the network.
a voltage event recorder
It plugs into your power outlet and tracks the voltage over time.
activity light.
It turns on when the card detects network traffic, so it intermittently flickers when operating properly.
optical time domain reflectometer
OTDRs determine continuity and, if there's a break, tell you exactly how far down the cable to look for the break.
vertical cross-connect.
Part of a network's backbone that supplies connectivity between a building's floors. For example, vertical cross-connects might connect an MDF and an IDF or IDFs and telecommunications closets within a building.
cable mismatch or fiber mismatch
Plugging a single-mode cable into a switch that expects multimode?
older 66-punchdown block VS 110 block
The 110 block introduces less crosstalk than 66 blocks,
customer premises equipment
The devices and inside wiring located at the premises of the subscriber and connected with a telecommunication channel of a carrier. The subscriber either owns or leases from the service provider.
light leakage,
The type of interference caused by bending a piece of fiber-optic cable past its maximum bend radius. Light bleeds through the cladding, causing signal distortion and loss.
near-end crosstalk
The unwanted signal coupling between pairs. It is measured at the end of a cable nearest the point of transmission. Contrast with far-end crosstalk.
smart jack
Type of NIU that enables ISPs or telephone companies to test for faults in a network, such as disconnections and loopbacks.
The most common type of patch panel today uses a special type of connector called
a *110 block*, or sometimes called a *110-punchdown block*.
Don't blow a good CAT 6 cable installation by buying a cheap patch panel—get
a CAT 6 patch panel! A CAT 6 panel can handle the 250-MHz frequency used by CAT 6 and offers lower crosstalk and network interference.
the DSL or cable modem supplied by your ISP is a network interface unit (NIU) that serves as
a demarc
What kind of rack you need If you're going to install big servers,
a four-post rack or a server rail rack.
A true external loopback requires
a loopback plug inserted into the NIC's port
*EXAM TIP* A single piece of cable that runs from a work area to a telecommunications room is called
a run.
the ideal number of demarc, MDF, IDF in one building
a single demarc, a single MDF, and multiple IDFs
A telecommunications room doesn't have to be
a special room dedicated to computer equipment.
Successful implementation of a basic structured cabling network requires three essential ingredients:
a telecommunications room, horizontal cabling, and a work area.
When the time comes to trace cables, network techs turn to a device called
a toner
EXAM TIP You'll see a tone probe referred to on the CompTIA Network+ exam as
a toner probe.
a toner
a tool that is used to trace wires between two rooms?
standby power supply
a type of UPS where power usually derives directly from the power line, until the power fails
All rack-mounted equipment uses a height measurement known simply as
a unit (U).
If your UPS comes on too often, it might be time to install
a voltage event recorder
Exam TIP: rack-mounted AC distribution boxes
an AC distribution system can supply multiple dedicated AC circuits to handle any challenging setups.
The three big issues with fiber are
attenuation, light leakage, and modal distortion.
as a signal progresses down a piece of wire, it becomes steadily weaker: this is called
attenuation.
If your problem system is clearly not connecting, eliminate the possibility of a failed switch or other larger problem by
checking to make sure other people can access the network,
UTP patch panels, like UTP cables,
come with CAT ratings,
Onboard NICs on laptops are especially notorious for breaking due to
constant plugging and unplugging.
A multimeter works perfectly well to test for
continuity,
*EXAM TIP* The *ANSI/TIA-606-B* standard
covers proper labeling and documentation of cabling, patch panels, and wall outlets.
Both NEXT and FEXT are measured in
decibels (dB).
wavelength mismatch
different runs of fiber use different wavelength signals. such as 1310 nm and 1530 nm
*EXAM TIP* The CompTIA Network+ exam uses the terms *110 block* and *66 block*
exclusively to describe the punchdown blocks common in telecommunication.
If you suspect a hardware problem,
first, check the link lights on the NIC and switch. If they're not lit, you know the cable isn't connected somewhere.
Multiple systems failing to access the network often points to
hardware problems.
(LACP) controls
how multiple network devices send and receive data as a single connection.
The best way to think of a demarc is
in terms of responsibility. If something breaks on one side of the demarc, it's your problem; on the other side, it's the ISP/phone company's problem.
Solid core
is a better conductor, but it is stiff and will break if handled too often or too roughly.
Stranded core
is not quite as good a conductor, but it will stand up to substantial handling without breaking.
A patch panel
is simply a box with a row of female ports in the front and permanent connections in the back, to which you connect the horizontal cables
dispersion
is when a signal spreads out over long distances.
Every piece of fiber has a certain bend radius limitation. If you bend a fiber-optic cable too much, you get
light leakage,
From a cabling standpoint, a work area is
nothing more than a wall outlet that serves as the termination point for horizontal network cables:
Your biggest concerns in the telecommunications room are
power and environmental issues.
The floor plan is the key to
proper planning;
"demarc"
refers to the physical location of the connection and marks the dividing line of responsibility for the functioning of the network.
TIA/EIA specifies that horizontal cabling should always be
solid core.
• Is the signal from any of the pairs in the same cable interfering with another pair? This common problem in UTP installations is called a
split pair.
wiremap
testing that all the wires on both ends of the cable connect to the right spot. A wiremap test will pick up shorts, crossed wires, and more.
Look for errors that point to physical disconnection. A key clue that you may have a physical problem is
that a user gets a "*No server is found*" error, or tries to use the operating system's network explorer utility and doesn't see any systems besides his or her own.
You must buy CAT-rated jacks for wall outlets to go along with
the CAT rating of the cabling in your network.
link aggregation
the ability to combine multiple connections between two devices within a LAN in order to increase data transfer rate.
Any cabling that runs from the NIU to whatever CPE is used by the customer is
the demarc extension.
a bad NIC can also generate this "can't see the network" problem. Use
the utility provided by your OS to verify that the NIC works.
loopback test.
this test sends data out of the nic and waits to see if it comes back.
The idea of structured cabling is
to create a safe, reliable cabling infrastructure for all of the devices that may need interconnection.
The key when planning a rack system is
to determine what sort of rack-mounted equipment you plan to have and then get the rack or racks for your space.
When you're testing a cable run, always include the patch cables as you test. This means
unplugging the patch cable from the PC, attaching a tester, and then going to the telecommunications room. Here you'll want to unplug the patch cable from the switch and plug the tester into that patch cable, making a complete test
If you don't have a floor plan—and this is often the case with homes or older buildings—
you'll need to create your own.
While every telephone installation varies, most commonly
you'll see one or more *strands* of 25-pair UTP cables running to the *66 block* in the telecommunications room on each floor (Figure 6-21).
Telecommunication room
—technically called the intermediate distribution frame (IDF)—is where all the horizontal runs from all the work areas come together. It is opposed to MDF.
Most network admin types staring at a potentially bad copper cable want to know the following:
• How long is this cable? If it's too long. • Are any of the wires broken or not connected in the crimp • Is there any place where two bare wires touch? This creates a short. • If there is a break, where is it? • Are all of the wires terminated in the right place+ • Is there electrical or radio interference from outside sources? • Is the signal from any of the pairs in the same cable interfering with another pair?
