Transcript Powerpoint - Chapter 18

Chapter Overview
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Documentation and Resources
Logs and Indicators
Network Testing and Monitoring Tools
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Product Documentation
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Hardware and software products usually
include documentation in some form.
You should always keep all product
documentation.
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Although you may be familiar with the devices or
software products you use, you might still need
the documentation later when you need to
reinstall, upgrade, or troubleshoot the network.
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CD-ROM Documentation Formats
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Text files. Many manufacturers use plain ASCII text
files to provide late-breaking information about
product problems, revisions, and compatibility issues.
Hypertext Markup Language Files. Some
manufacturers create documentation in Hypertext
Markup Language (HTML) format and include it with
the product on a CD-ROM.
Adobe Acrobat Portable Document Format files.
Acrobat creates and displays documents in a
proprietary format called the Portable Document
Format (PDF).
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PDF files preserve all the original design elements, layout, and
formatting characteristics of the original documents.
The .pdf format has become a de facto publishing standard in the
computing industry.
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An Example of an Adobe Acrobat
PDF File
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Telephone Support
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Free telephone support is a thing of the past.
Some products include free technical support for
a limited time or a limited number of incidents
before the manufacturer begins charging a fee.
Because of the expense, determining when to
call for help is more difficult than it used to be.
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People are more likely to find other sources of support
before paying for help.
Sometimes calling for technical support is necessary.
Look for help on the Web and Usenet first, and
call technical support as a last resort.
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Online Resources
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Marketing collateral. Includes datasheets, features and
benefits lists, product comparisons, product reviews, and
other sales literature
Product manuals. Can be more valuable if the site has a
search engine
Technical documents. Frequently more concerned with the
theoretical aspects of the product than with day-to-day
operations
Frequently asked questions (FAQs). Address common
problems; can be an excellent product evaluation resource
Technical support databases. Let you search for keywords
or error messages, and provide information on solutions
and links to software patches
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Online Resources (Cont.)
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File downloads. Let you see how many patches have
been issued for a product, which is a good way of
evaluating the product before buying it
Online messaging. The Web equivalent of the old
bulletin board systems, where you leave a text
message and receive a reply from a technical support
representative
Live support. Usually a chat application that provides
a live text-messaging link between users and
company representatives
Manufacturer’s contact information. E-mail addresses
and telephone numbers for technical support, and
other contact information
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Usenet
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Usenet is a worldwide, text-based Internet bulletin
board system that consists of newsgroups devoted to
many topics.
Usenet is not as user-friendly as the Web, but it
provides an enormous amount of valuable technical
information.
To access Usenet newsgroups, you must have a
newsreader client program and access to a news
server.
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The clients and servers communicate with each other by
using a specialized TCP/IP protocol called the Network News
Transfer Protocol (NNTP).
Most Internet service providers (ISPs) include access to a
news server as part of a standard Internet access
subscription, but the quality of the service varies.
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The Usenet Newsgroup List
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Usenet Message Headers
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A Usenet Newsgroup Message
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The Microsoft TechNet Interface
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Books and Periodicals
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Networking and computer books are an excellent
resource for background information and networking
theory.
Many books include a searchable electronic version
on a CD-ROM.
Magazines and trade newspapers are good places to
look for current technical information and industry
news.
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Keep in mind that information in a typical monthly magazine
is written at least three to four months before you see the
issue.
Weeklies usually provide more timely information.
Many weekly trade newspapers are now available online.
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Link Pulse Lights
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Most Ethernet network interface adapters that
use unshielded twisted-pair (UTP) cable have a
light-emitting diode (LED) that is lit when the
adapter is connected to a functioning hub.
The hub usually has an additional LED for each
port that indicates from either end of the patch
cable whether the devices are connected.
Link pulse lights can tell you whether a computer
is wired to the hub properly.
When an Ethernet adapter and a hub are
properly connected, they exchange signals to test
the connection.
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The Link Pulse LED on a Network
Interface Adapter
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The Link Pulse LED on a Hub
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Normal Link Pulse (NLP) Signals
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On 10Base-T and 10Base-FL equipment, the
signal exchanged by network interface adapters
and hubs is called a normal link pulse (NLP).
The NLP signals
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Last for 2 milliseconds
Repeat at intervals of 16.8 milliseconds
Occur only when the network is not busy transmitting
data, so they do not interfere with normal operations
When the LEDs at both ends of the connection
are lit, the NLP signals generated by each device
are reaching the other device.
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Fast Link Pulse Signals
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Fast Ethernet and Gigabit Ethernet equipment that supports
multiple speeds uses fast link pulse (FLP) signals.
FLP signals differ from NLP signals in that they include a 16-bit
data packet that the devices use to autonegotiate their
connection speed.
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The data packet contains a link code word that consists of a
selector field and a technology ability field.
The devices use these fields to advertise their capabilities, including
the speeds they can run at and whether they support full-duplex
communications.
By examining the link code word supplied by the other device,
the network interface adapter and the hub both configure
themselves to use the best transmission mode that they have in
common.
FLP signals are fully compatible with the NLP signals that are
used by devices that cannot operate at multiple speeds.
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Error Displays
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The most obvious indication of a computer problem is an error
message.
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In most cases, error messages cannot give you specific
information about a problem with the network itself.
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Error messages are generated primarily by applications and
operating systems.
There is usually no way for the computer to test or communicate
with network components except for other computers.
An error message generated by an operating system might tell you
that the computer could not communicate with another computer
on the network, but it usually cannot tell you why unless the
problem is with the computer generating the message.
If you do not understand an error message, record the exact
message, including all number and letter codes, memory
addresses, and other types of information.
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Event Logs
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An event log is a running record of processes that
documents an operational history of the product
involved.
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Many applications, operating systems, and networking
components maintain logs of their activities.
You should check the logs on a regular basis.
Some applications let you specify whether you want
them to log their activities and how much detail you
want in the logs.
You should consider the amount of detail you want in
the logs.
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Selecting the most detailed option might not always be best.
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The General Properties Tab in the IIS
Extended Logging Properties Dialog
Box
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The Extended Properties Tab in the
IIS Extended Logging Properties
Dialog Box
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The Windows 2000 Event Viewer
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Event Viewer
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Some logs are maintained and displayed by a
separate application, such as the Event Viewer
included in Microsoft Windows 2000 and
Microsoft Windows NT.
To launch Event Viewer in Windows 2000, select
Event Viewer on the Start menu’s
Programs/Administrative Tools group.
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By default, the application displays the logs for the current
system.
You can also view the logs of another computer
running Windows 2000.
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Event Viewer (Cont.)
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Event Viewer maintains lists of messages generated
by various elements of the operating system.
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By default, Microsoft Windows 2000 Professional
contains three different logs—an Application Log, a
Security Log, and a System Log—all of which are
maintained independently.
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Each log entry is listed as a separate item with the date and
time that it was generated, the process that generated it,
the event ID, and other important information.
The Microsoft Windows 2000 Server products include these
three logs, plus others, depending on the services installed.
Each event in each log is classified as Information,
Warning, or Error.
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The Event Properties Dialog Box
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Network Management Products
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Error messages generated by network components, such as
routers or computers at remote locations, can be difficult to
monitor.
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Network management products provide a comprehensive view
of network systems and processes.
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A stand-alone router does not have a screen to display error
messages, but many networking devices can supply information
about their status.
These products use a distributed architecture based on a
specialized management protocol, such as the Simple Network
Management Protocol (SNMP) or the Remote Monitoring (RMON)
protocol.
Network management products often include other functions,
such as software distribution and metering, network diagnostics,
network traffic monitoring, and report generation.
Deploying a network management system is a complex
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undertaking.
SNMP
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SNMP is a Transmission Control Protocol/Internet Protocol (TCP/IP)
application layer protocol and query language that specially
equipped networking devices use to communicate with a central
console.
Many networking hardware and software products use SNMP
agents to
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Gather information about the product and deliver it to a computer
designated as the network management console
Gather specific information about the network devices and store it as
managed objects in a management information base (MIB)
SNMP agents transmit MIBs to the console using SNMP messages,
which are carried inside User Datagram Protocol (UDP) datagrams.
The console collates the information received from the agents and
provides a composite picture of the network and its processes.
An agent can generate a special message called a trap, which
causes the console to alert of a potentially dangerous condition.
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Windows 2000 System Monitor
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The Add Counters Dialog Box in
System Monitor
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The Performance Console in System
Monitor
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The Performance Logs and Alerts
Feature in the Performance Console
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The Novell Netware MONITOR.NLM
Application
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Protocol Analyzers
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A protocol analyzer captures a sample of network traffic,
decodes the packets into the language of the individual
protocols that they contain, and lets you examine them in
detail.
Capturing and displaying network traffic is relatively easy, but
interpreting and using the information for troubleshooting
requires a detailed understanding of networking protocols.
Protocol analyzers are useful tools, but they can also be used
for malicious purposes.
A protocol analyzer can be either
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A device with a proprietary interface that you connect to a network
to capture traffic, or
A software program that runs on a computer that is already
connected to the network
Protocol analyzers typically work by switching their network
interface adapter into promiscuous mode.
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The Network Monitor Capture
Summary Window
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The Network Monitor Detailed
Information Display
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An Expanded TCP Header
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The Network Monitor Raw Data
Display
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Crossover Cables
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A crossover cable is a good tool to use for eliminating
the hub and the cables as possible sources of a
network communications problem.
If two computers seem to be properly connected with
a hub and prefabricated cables (or an internal cable
run and patch cables), and they are not
communicating, try connecting the computers with a
crossover cable that you know works properly.
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If the computers can communicate with the crossover cable,
the problem is in either the hub or the cables connecting the
computer to the hub.
If the computers fail to communicate with the crossover
cable, the problem is in one or both of the computers or
network interface adapters.
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Hardware Loopback Connectors
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A loopback connector is an inexpensive device that
you plug into a jack.
The loopback connector redirects the outgoing
signals from the device right back into it.
Many adapters have a diagnostic utility built into their
configuration programs.
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After plugging the loopback connector into the adapter port,
you run the diagnostic program, and the loopback connector
transmits a series of signals out through the adapter.
If the adapter receives the signals back in exactly the same
format as they were sent, the adapter passes the test.
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A Typical Tone Generator and
Locator
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Tone Generators and Locators
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A basic way to identify and test a cable connection is to use a tone
generator and locator, also known as a "fox and hound" cable
tester.
You connect a tone generator to a cable at one end, and it
transmits a signal over the cable.
The tone locator is a separate device that can detect the
generator's signal, either by touching it to the conductor in the
cable or by touching it to the cable insulation.
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When the locator detects the generator's signal, it emits an audible
tone.
You can use a tone generator and locator to test an entire cable or
to test the individual wire connections inside a UTP cable.
Tone generators and locators are most commonly used to identify
the cable that belongs to a particular connection.
The tone generator and locator is the simplest and most
inexpensive type of cable tester.
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Wire Map Testers
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A wire map tester is similar in principle to the tone generator
and locator, except that it tests all the wire connections in a UTP
cable at once.
A wire map tester consists of two parts that you connect to the
opposite ends of a cable.
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A wire map tester can detect transposed wires, open circuits,
and shorts, just as a tone generator and locator can.
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The unit at one end transmits signals over all the wires, which are
detected by the unit at the other end.
However, it does all the tests simultaneously and provides you with
a simple readout telling you what is wrong.
The one common cable fault that a typical stand-alone wire map
tester cannot detect is a split pair.
Wire map testers are relatively inexpensive stand-alone devices
and are good investments for small- to medium-sized internal
cable installations.
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A Typical Multifunction Cable Tester
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Multifunction Cable Testers
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Handheld devices that test cable connections and
compare the results to standard values that have
been programmed into the unit
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Display a list of pass or fail ratings for the individual tests
Can perform basic wire mapping tests in addition to
testing length, attenuation, near end crosstalk
(NEXT), power sum NEXT (PSNEXT), equal level far
end crosstalk (ELFEXT), power sum ELFEXT
(PSELFEXT), propagation delay, delay skew, and
return loss
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Multifunction Cable Testers (Cont.)
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Multifunction cable testers can be dangerous because
of the very strengths they advertise.
Some marketing materials imply that you can rely on
the device to tell you if the cables are installed
correctly, without knowing what the measurements
mean.
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This is true, if the tester is calibrated to the proper
standards.
If you do not know what each test represents, you
are relying on the manufacturer of the device to set it
to the proper standards.
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In some cases, official standards for certain cable types have
not yet been ratified.
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Chapter Summary
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Documentation and resources
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Product documentation can be a valuable network
troubleshooting tool.
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You should always keep all the documentation that
comes with your hardware and software.
Web sites for many hardware and software
manufacturers offer a variety of resources for the
network administrator, including technical
documents, FAQs, online messaging, and technical
support databases.
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Chapter Summary (Cont.)
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Logs and indicators
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LEDs and other lights are frequently useful
indicators of a piece of a hardware component’s
current status.
The link pulse LEDs on Ethernet hubs and network
interface adapters indicate when these devices are
connected properly.
Tools like the Windows 2000 Performance console
enable you to monitor ongoing computer and
network operations in real time.
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Chapter Summary (Cont.)
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Network testing and monitoring tools
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A tone generator and locator is a simple cabletesting device that determines whether a cable is
carrying a signal.
Wire map testers test all four of the wire pairs in a
UTP cable at the same time.
Multifunction cable testers perform a
comprehensive battery of tests on a cable
connection and compare the results to established
standards.
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