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Networking BASICS
Managing a
Local Area
Network
Unit 2
Lesson 8
Lesson 8—Networking BASICS
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Objectives
• List the proactive steps to be taken to
keep a network server in operation.
• Tell how server performance can be
monitored.
• Explain how SNMP and network
monitors are used.
• List and describe the features of
common network troubleshooting tools.
Lesson 8—Networking BASICS
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Managing the Server
• This is one of most important
jobs of a network manager.
• Take steps to prevent errors.
• Monitor for problems.
Lesson 8—Networking BASICS
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RAID
• Redundant Array of
Independent Drives
• Fault-tolerant hard drives
• There are six common
levels.
Lesson 8—Networking BASICS
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RAID Levels
• RAID 0 – Striping across drives.
• RAID 1 – Disk mirroring and disk
duplexing.
• RAID 2 – Uses error correction
code (ECC).
• RAID 3 – Uses parity error
checking.
Lesson 8—Networking BASICS
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RAID Levels
Lesson 8—Networking BASICS
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RAID Levels
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RAID Levels
• RAID 4 – Larger stripes.
• RAID 5 – Divides parity checking
across drives.
• Dual-level RAID – Combines
multiple hardware RAID arrays.
• Not all levels are fully supported.
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Backups
• Backups copy data to another media
and store it in a secure location.
• Optical discs (CD-ROM and DVD) are
not often used.
• Archive bit – This is set when a file is
backed up and cleared when a file is
changed.
• It is important to test backups.
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Types of Backups
• Full backup
• Differential backup
• Incremental backup
• Copy backup
• Daily copy
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Uninterruptible Power Supply
• The UPS supplies power to the
server if electrical power fails.
• Power conditioning – Ensures a
correct and constant level of power.
• Surge protector – Prevents spikes
from reaching the server.
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Uninterruptible Power Supply
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Virus
• A virus instructs the computer to
perform an operation without the
user’s consent or knowledge.
• Viruses are destructive or nondestructive.
• Viruses are replicated primarily by
e-mail.
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Types of Viruses
• Macro – Attaches to application
program and executes.
• Polymorphic – Changes
appearance each time it
replicates.
• Stealth – Hides its presence
from detection.
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Monitoring Server
• It monitors the performance of
the server’s CPU.
• It can be done at one time or as
an average.
• When the CPU is constantly
over 90%, that indicates that
the server is overloaded.
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Monitoring Server
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Server RAM
• RAM is divided into page
frames.
• The NOS pages out frames
when they are no longer
needed or when a frame is
needed for other data.
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Page Faults
• Page fault – Swap data
back into RAM page.
• Soft page fault – Data
retrieved from RAM.
• Hard page fault – Data
retrieved from hard drive.
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Page Faults
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Monitoring Network Performance
• The entire network must
be monitored.
• There are a variety of
hardware and software
tools available.
Lesson 8—Networking BASICS
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SNMP
• Simple Network Management
Protocol
• Part of TCP/IP suite
• Gather data about network
performance
• Software agents sent to
management information base
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SNMP
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Network Monitors
• There are software packages to
monitor network health.
• They identify late collisions, jabber,
and negative frame count.
• They are available for all operating
systems.
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Protocol Analyzers
• They are also called packet
sniffing tools.
• Promiscuous mode –
Captures all network
packets.
• Data can be filtered.
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Hardware Tools
• Multimeter – Measures
characteristics of electric current.
• Cable checker – Determines
status of cable.
• Time domain reflector – Sends
signal and records return.
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Summary
• The role of managing a computer network is the job of the network manager and involves two major tasks: taking necessary
proactive steps to prevent problems from occurring and watching for symptoms that may indicate something on the network is
not right. If a symptom reveals a problem, the problem must be
fixed immediately before things get worse.
• A variety of preventive measures can be taken to make the
server as stable as possible. Fault-tolerant server hard drives
are based on a standard known as RAID (Redundant Array of
Independent Drives). The fundamental idea behind RAID is to
install several disk drives inside the server. This array of disk
drives appears to the server as a single drive. If one of the
drives fails, the other hard drives keep the server and network
functioning.
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Summary (continued)
• There are six common levels of RAID: RAID 0 through RAID 5.
Yet RAID does not diminish the need for data backups. Data
must be copied regularly to another media and stored in a
secure location. Although CD and DVD technology is often used
for backups of data stored on client computers, it is rarely used
for data backups of network file servers. There are five basic
types of backups: full backup, differential backup, incremental
backup, copy backup, and daily copy. Many network managers
perform a full backup once a week and a differential backup
once a day.
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Summary (continued)
• An uninterruptible power supply (UPS) is an external device
located between the outlet for electrical power and the server.
The primary purpose of a UPS is to continue to supply power to
the server in the event the electrical power fails. Yet the UPS is
much more than a large battery. UPS systems interface with the
NOS on the server to ensure that an orderly shutdown will occur
and “clean” the electrical power before it reaches the server. A
computer virus is a computer program that instructs a computer
to perform an operation without the user’s knowledge or consent. Computer viruses can be either destructive or nondestructive. Computer viruses are usually designed to replicate and
quickly infect other computers.
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Summary (continued)
• Managing the server involves not only taking proactive steps to
prevent problems from occurring, but also monitoring the server
so any problems that do occur can be quickly identified and
solved. Monitoring the performance of the server includes
watching the CPU, hard drive, and RAM. Monitoring the performance of the CPU can reveal whether the system is training
under the load of the network or has power to spare. Programs
that monitor the CPU utilization are found on almost every NOS.
Lesson 8—Networking BASICS
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Summary (continued)
• Compared to the CPU, RAM is the second-most important
component in a file server that should be closely watched.
Because RAM is so vital to the operation of the server, a server
that lacks sufficient RAM can cause all network users to wait
unnecessarily long periods of time for their programs to load and
for the server to answer their requests. Another important
component of the server that needs to be monitored is the hard
drive. The total amount of free disk space left on the hard drive
is especially important. If the amount of free disk space is 20
percent or less of the entire hard drive, more free space must be
found.
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Summary (continued)
• An array of tools can be used to monitor the performance of the
network. The Simple Network Management Protocol (SNMP) is
part of the TCP/IP protocol suite. SNMP allows computers and
network equipment to gather data about network performance.
In addition to SNMP, other software packages can be used to
monitor the health of the network. Known as network monitors,
these packages provide a wealth of network statistics. Protocol
analyzers capture packets so they can be analyzed. They also
translate the contents of the packet from a form the computer
and network uses to a form humans can read.
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Summary (continued)
• A variety of hardware tools can also be used for digging deeper
to discover the source of a network problem. A multimeter is a
tool that measures the characteristics of an electric current. A
cable checker is used to determine whether a cable can send
and receive packets. A cable tester performs the same function
as a cable checker, but also provides additional results. A time
domain reflectometer (TDR) is a sophisticated device that sends
a signal down a cable and then records the return of the signal.
Handheld network analyzers combine the best features of
protocol analyzers, multimeters, cable checkers and testers, and
TDRs into a single small device.
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