Instructors Notes

droppercauseNetworking and Communications

Oct 28, 2013 (4 years and 12 days ago)

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Network+ Guide to Networks, 5
th

Edition


6
-
1





Chapter
6


Network Hardware



At a Glance


Instructor’s Manual Table of Contents




Overview




Objectives




Teaching Tips




Quick Quizzes




Class Discussion Topics




Additional Projects




Additional Resources




Key Terms


Network+ Guide to Networks, 5
th

Edition


6
-
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Lecture Notes


Overview


Students need

to understand how data arrives at its destination. In data networks, the task of
directing information efficiently to the correct destination is handled by hubs, routers, bridges,
and switches. In this chapter, students will learn about these devices and
their roles in managing
data traffic. Material in this chapter relates mostly to functions occurring in the Data Link and
Network layers of the OSI model. Some material also relates to the Physical layer. Students will
learn the concepts involved in moving

data from place to place, including issues related to
switching and routing protocols. Students will also see pictures of the hardware
-

hubs, switches,
bridges, and routers
-

that make data transfer possible. In addition, students will learn all about
ne
twork interface cards, which serve as the workstation’s link to the network and are often the
source of connectivity problems.



Chapter Objectives


After reading this chapter and completing the exercises, the student will be able to:



Identify the function
s of LAN connectivity hardware



Install, configure, and differentiate between network devices such as, NICs, hubs, bridges,
switches, routers, and gateways



Explain the advanced features of a switch and understand popular switching techniques,
including VLAN

management



Explain the purposes and properties of routing



Describe common IPv4 and IPv6 routing protocols



Teaching Tips


NICs (Network Interface Cards)


1.

Define and describe
NICs (network interface cards)
.


2.

Point out that
nearly all NICs contain a data t
ransceiver
.


3.

Explain why
NICs belong to both the Physical layer and Data Link layer of the OSI
model.


4.

Describe how advances in NIC technology are making NICs smarter than ever.


5.

Emphasize that NICs do not analyze information added by the protocols in Laye
rs 3
through 7 of the OSI model.


6.

Explain why it is important to understand NICs.


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Types of NICs


1.

Explain what a student should know before ordering or installing a NIC.


2.

Describe dependencies of
NICs.


3.

Introduce the
Internal Bus Standards category of NICs

that are installed on an expansion
board inside a computer.


4.

Define and describe the term bus.


5.

Define and describe the term expansion slot.


6.

Define and describe the term expansion card
.


7.

Point out that multiple bus types exist.


8.

Note that to become part
of a computer’s bus, an expansion board must use the same bus
type.


9.

Introduce and describe the PCI bus

type
.


10.

Use Figure 6
-
1 to illustrate a PCI NIC.


11.

Describe the older ISA bus
type
and compare PCI to ISA.


12.

Intr
oduce and describe the PCIe bus type.


13.

Desc
ribe the advantages

of

PCIe
over
PCI
.


14.

Explain how the PCIe slots differ from PCI slots. Include a discussion
on
PCIe lanes.


15.

Use Figure 6
-
2 to illustrate a PCIe NIC.


16.

Explain how to determine the type of bus a PC uses.


17.

Use Figure 6
-
3 to illustrate a moth
erboard with multiple expansion slots.


18.

Explain how to determine the best NIC for a PC if the PC motherboard supports more
than one kind of expansion slot.


19.

Introduce the Peripheral Bus Standards category of NICs that are installed externally.

a.

PCMCIA (Pers
onal Computer Memory C
ard International Association)

b.

USB (universal serial bus)

c.

CompactFlash

d.

FireWire (IEEE 1394)


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20.

Explain

the Personal Computer Memory Card International Association
’s

role in setting
standards for peripheral

devices.

a.

PC C
ard

b.

CardBus

c.

Expre
ssCard


21.

Describe the peripheral PCMCIA standard called
PC Card
.


22.

Describe the peripheral PCMCIA standard called CardBus.


23.

Use Figure 6
-
4 to illustrate a CardBus NIC.


24.

Describe the peripheral PCMCIA standard called ExpressC
ard
.


25.

Use Figure 6
-
5 to illustrate

two ExpressCard modules.


26.

Introduce and describe the
USB

peripheral bus standard.


27.

Use Figure 6
-
6

to illustrate a USB NIC.


28.

Introduce and describe the Firewire peripheral bus standard.


29.

Use Figure 6
-
7

to illustrate Firewire connectors.


30.

Introduce and desc
ribe the CompactFlash peripheral bus standard.


31.

Use Figure 6
-
8

to illustrate a CompactFlash NIC.


32.

Introduce and describe the o
n
-
board peripheral bus standard.


33.

Introduce and describe the wireless peripheral bus standard.


34.

Use Figure 6
-
9 to illustrate a w
ir
eless NIC.


Teaching

Tip



Students may find more information on how buses work at
http://computer.howstuffworks.com/computer
-
buses
-
channel.htm




Teaching

Tip


Students may f
ind more information on PCMCIA and Linux

at

http://pcmcia
-
cs.sourceforge.net

.



Teaching

Tip


Students may find more information on PCMCIA/PC Card and CardBus frequently
asked questions

at

http://www.sycard.com/pcard_qa.html



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Installing NICs


1.

Describe the three general steps to install a NIC:

a.

Install NIC hardware

b.

Install NIC software

c.

Configure NIC


2.

Define and explain the term EEPROM.


3.

Explain how to
install and configure expansion card NIC hardware.


4.

Use Figure 6
-
10 to illustrate a properly installed NIC.


5.

Explain how to install
a
PCMCIA
-
standard NIC into a laptop.


6.

Use Figure 6
-
11 to illustrate
the
installation of a PCMCIA
-
standard NIC.


7.

Explain how
to install and configure expansion card NIC software.


8.

Define the term device driver.


9.

Explain how drivers are installed on purchased computers and computer with new
hardware added.


10.

Note that most operating systems come with a multitude of built
-
in device

drivers.


11.

Emphasize that i
f the op
erating system cannot find a driv
er for the new hardware the
driver will have to be installed and configured using NIC software and the operating
system interface.


12.

Explain h
ow

to install NIC software from a Windows Vista

interface.


13.

Use Figure 6
-
12 to illustrate the Windows Vista Update Driver Software dialog box.


14.

Describe how a student may interpret NIC LED indicators to verify NIC functionality
after installation.


15.

Define an IRQ (interrupt request).


16.

Define an interrup
t.


17.

Define and explain an IRQ number.


18.

Note that most often, NICs use IRQ 9, 10, or 11.


19.

Use Table 6
-
1 to illustrate IRQ assignments.


20.

Explain what happens if two devices use the same interrupt and how it can be corrected.

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21.

Define and explain CMOS.


22.

Define
and explain BIOS.


23.

Define memory range and explain how
t
he NIC and CPU use it to communicate.


24.

Define the base I/O port setting and explain how a NIC uses it.


25.

Introduce and explain firmware settings.


26.

Explain how to change firmware.

Include a discussion o
n configuration the NIC
configuration utility.


27.

Describe how to perform diagnostics with the NIC configuration utility.

a.

Define and describe a loopback plug,

b.

Describe a loopback test.


Choosing the Right NIC


1.

Explain the factors to consider when selecting a

NIC.


2.

Use T
able 6
-
2 to illustrate NIC characteristics.


Teaching

Tip



Demonstrate
the availability modern
Linksys network adapters utilizing various bus
types by navigating to the Linksys adapter’s product page at
htt瀺LLwww.lin歳ysbycisc漮oomLrpLe港灲潤uctsLA摡灴ers





Quick Quiz 1


1.

True or
F
alse:
A NIC has no room for a transceiver.

Answer: False


2.

A bus is defined by ____.

a.

data path speed

b.

pin size

c.

data path width and clock speed

d.

d
ata path width and
pin

size

Answer:
C


3.

True or
F
alse:
One disadvantage to using wireless NICs is that currently they are
somewhat more expensive than wire
-
bound NICs using the same bus type.

Answer: True


4.

____ is a set of data or instructions that has bee
n saved to a ROM.

Answer:
F
irmware

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5.

If the ___ NIC
LED
indicator
light
is blinking, this indicates that the NIC is functional
and transmitting frames

to the network.

a.

ACT

b.

LNK

c.

TX

d.

RX

Answer:
C



Repeaters and Hubs


1.

Define and describe a repeater.


2.

Define
and

describe a hub.


3.

Describe

how
placement of hubs in a network design can vary.


4.

Use Figure 6
-
13 to suggest how hubs can fit into the overall design of a network.


5.

Emphasize that dozens of types of hubs exist and explain how they vary.


6.

Use Figure 6
-
1
4

to
i
llustrate a small stand
-
alone hub.


7.

Point out that hubs have mostly been replaced by switches or routers and explain why.


Teaching

Tip



Demonstrate the availability modern Linksys network routers by navigating to the
Linksys router product page at
:

http://www.linksysbycisco.com/US/en/products/Routers





Bridges


1.

Define and describe bridges.


2.

Explain the advantage of using bridges over repeaters and hubs.


3.

Explain the disadvantage of
using bridges.


4.

Explain how a bridge translates data between two segment types.


5.

Use Figure 6
-
15 to illustrate a bridge’s use of a filtering database.


6.

Point out that after bridge installation, several methods may be used to learn about the
network and dis
cover the destination address for each packet it handles.


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7.

Emphasize that bridges are nearly extinct and explain why.


Teaching

Tip



Demonstrate the availability modern Linksys network bridges by navigating to the
Linksys bridge product page at
:

http://www.linksysbycisco.com/US/en/products/Bridges





Switches


1.

Define and describe switches.


2.

Emph
asize why switches can
interpret MAC address information.


3.

Note the components within switc
hes.


4.

Discuss multiport switches and their advantages over a bridge.


5.

Use Figure 6
-
1
6

to illustrate
switches
.


6.

Discuss how switches were used historically.


7.

Describe the disadvantages of switches
,

noting that some network administrators have
replaced backb
one routers with switches
.


8.

Explain the best way to ensure that a switch is installed properly.


9.

Review the general steps for installing a switch.


10.

Use Figure 6
-
17 to illustrate how to connect a workstation to a switch.


11.

Use Figure 6
-
18 to illustrate a swi
tch on a small network
.


12.

Introduce switching methods.


13.

Define and describe the cut
-
through mode switching method.


14.

Describe the advantages and disadvantages of the cut
-
through method, as well as where it
is best implemented.


15.

Define and describe the store
-
and
-
forward mode switching method.


16.

Describe the advantages and disadvantages of the store
-
and
-
forward mode, as well as
where it is best implemented.


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Teaching

Tip



Demonstrate the availability modern Linksys network switches by navigating to the
Linksys

bridge product page at
:

http://www.linksysbycisco.com/US/en/products/Switches




Teaching

Tip



Students may find more information on how switches work at
:

http://computer.howstuffworks.com/lan
-
switch.htm




VLANs and Trunking


1.

Define a VLAN (virtual local area networks).


2.

Define the term broadcast domain.


3.

Define the term collision domain and contrast it with a broadc
ast domain.


4.

Use Figure 6
-
19 to illustrate a simple VLAN design.


5.

Describe the advantage
s

and reasons for using a VLAN.


6.

Explain how to create and maintain a VLAN.


7.

Emphasize the critical step in creating the VLAN.


8.

Use Figure 6
-
20 to illustrate the result

of the
show vlans

command on a Cisco switch
.


9.

Discuss potential useful situation for VLANs.


10.

Define
the term
trunking.


11.

Define the term trunk.


12.

Explain the advantages of VLAN trunking.


13.

Note considerations in VLAN configuration planning.


Teaching

Tip



Students may find more information on
Understanding VLAN Trunk Protocol
(VTP)

from Cisco at
http://www.cisco.com/en/US/tech/tk389/tk689/technologies_te
ch_note09186a0080
094c52.shtml





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STP (Spanning Tree Protocol)


1.

Introduce and define STP (Spanning Tree Protocol).


2.

Use Figure 6
-
21 to illustrate an enterprise
-
wide switched network requiring STP.


3.

Review the three steps STP performs.


4.

Use Figure 6
-
22 to

illustrate STP
-
selected paths on a switched network.


5.

Review the history of STP.


6.

Discuss the newer protocol as well as the proprietary protocols.


7.

Emphasize
that
when installing switches on your network, you do not need to enable or
configure STP (or the

more current version that came with your switch).


Content and Multilayer Switches


1.

Define a
L
ayer 3 switch.


2.

Define a
L
ayer 4 switch.


3.

Define a content switch
.


4.

De
scribe the
advantages

and disadvantages

of these types of switches
.


5.

Note that
distinguishi
ng factors between L
ayer

3 and Layer 4 switches are manufacturer
dependent.


6.

Discuss higher layer switches and their use.



Routers


1.

Define and describe a router.


Router Characteristics and Functions


1.

Explain the
strength of
routers.


2.

Emphasize that route
rs are indispensible in large WAN and LANs like the Internet.


3.

Describe the components in a router.


4.

Define and describe a modular router.


5.

Note the use
o
f inexpensive routers in the home and small office.

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6.

Use Figure 6
-
2
3

to illustrate
three routers.


7.

Desc
ribe the tasks performed by routers.


8.

Describe the optional functions a router may contain.


9.

Describe the two methods of directing network traffic:

a.

Static routing

b.

Dynamic routing


10.

Describe the installation characteristics of small networks and large networ
ks.


11.

Use Figure 6
-
2
4

to illustrate
the placement of routers on a LAN
.


Routing Protocols


1.

Define and describe the term best pat
h
.


2.

Describe a routing protocol.


3.

Define and describe router convergence time.


4.

Introduce d
istance
-
vector routing protocols
.


5.

Exp
lain how the
RIP (Routing Information Protocol)

works.


6.

Explain how
RIP
v2

(Routing Information Protocol

version 2
)

works.


7.

Explain how BGP
(Border Gateway Protocol)

works.


8.

Introduce
l
ink
-
state routing protocols.


9.

Explain how
OSPF (Open Shortest Path First)

works.


10.

Explain how
IS
-
IS (Intermediate System to Intermediate System
)

works.


11.

Introduce
the

concept of
hybrid routing protocol
s
.


12.

Explain how the
EIGRP (Enhanced Interior Gateway Routing Protocol)

works.



Gateways and Other Multifunction Devices


1.

Define

and describe gateways.


2.

Discuss popular gateways.


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Teaching

Tip


Stu
dents may find more information

on

gateway protocols at
:

http://www.cisco.com/en/US/tech/
tk1077/tsd_technology_support_protocol_home.html





Quick Quiz 2


1.

True or False: Repeaters operate in the Physical layer of the OSI model.

Answer: True


2.

True or
F
alse
: Bridges are protocol independent.

Answer: True


3.

Switches that operate anywhere betw
een Layer 4 and Layer 7 are also known as ____or
application switches.

Answer: content switches


4.

____
is a technique in which a network administrator programs a router to use specific
paths between nodes.

Answer:
Static routing


5.

A gateway must operate
at ____ of the OSI model.

a.

multiple layers

b.

Layer 2

c.

Layer 3

d.

Layers 4
-
7

Answer: A



Class Discussion Topics


1.

The author indicated
on page 246 that
that one disadvantage to using wireless NICs is
that they are
currently
somewhat more expensive than wire
-
bound

NICs using the same
bus type.

Discuss whether this is still true
today
and what factors
are moving wireless
NICs into a more dominant role, if any.


2.

Many students may most likely have a small home network or know someone who does.
Have student describe th
e communications devices in these networks. Are they wireless
or wired? Are there routers, switches, or hubs?

Describe experiences goo
d

and bad with
these networks.







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Additional Projects


1.

Have each student research available
routers.

T
he

report should
include a write
-
up for
three to five

devices. Included in the write
-
up should be a description of the device
,

including the
manufacturer, the model, the
seller, the cost,
a
nd
a summary of the
manufacturer specifications.


2.

Have students research the EIGRP r
outing protocol in more depth. The student should
provide a report
,

including sections on: Introduction, Background and history, Technical
S
pecifications, Implementation, Barriers, and Summary.



Additional Resources


1.

PCMCIA Official
W
eb

site

http://www.pcmcia.org/



2.

PCI Special Interest Group

http://www.pcisig.com/home



3.

USB (Universal Serial Bus) Implementer's Forum

http://www.usb
.org/home



4.

CompactFlash Association

http://www.compactflash.org


5.

CiscoPress Sample Chapter on VLANs and Trunking

http://www.ciscopress.co
m/articles/article.asp?p=29803



6.

Cisco router information

http://www.cisco.com/en/US/products/hw/routers/index.html




Key Terms




802.1D

-

The IEEE standard that describes, among o
ther things, bridging and STP
(Spanning Tree Protocol).



802.1w

-

The IEEE standard that describes RSTP (Rapid Spanning Tree Protocol), which
evolved from STP (Spanning Tree Protocol).



application switch

-

A switch that provides functions between Layer 4 a
nd Layer 7 of
the OSI model.



base I/O port

-

A setting that specifies, in hexadecimal notation, which area of memory
will act as a channel for data traveling between the NIC and the CPU. Like its IRQ, a
device’s base I/O port cannot be used by any other de
vice.



basic input/output system

-

See

BIOS.



best path

-

The most efficient route from one node on a network to another. Under
optimal network conditions, the best path is the most direct path between two points.
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However, when traffic congestion, segment fa
ilures, and other factors create obstacles,
the most direct path may not be the best path.



BGP (Border Gateway Protocol)

-

A complex routing protocol used on border and
exterior routers. BGP is the routing protocol used on Internet backbones.



BID (bridge I
D)

-

A combination of a 2
-
byte priority field and a bridge’s MAC address,
used in STP (Spanning Tree Protocol) to select a root bridge.



BIOS (basic input/output system)

-

The firmware attached to a computer’s motherboard
that controls the computer’s commun
ication with its devices, among other things.



Border Gateway Protocol

-

See

BGP.



border router

-

A router that connects an autonomous LAN with an exterior network


for example, the router that connects a business to its ISP.



bridge

-

A connectivity device

that operates at the Data Link layer (Layer 2) of the OSI
model and reads header information to forward packets according to their MAC
addresses. Bridges use a filtering database to determine which packets to discard and
which to forward. Bridges contain
one input and one output port and separate network
segments.



bridge ID

-

See

BID.



broadcast domain

-

A combination of ports on a switch (or multiple switches) that make
up a Layer 2 segment. To be able to exchange data with each other, broadcast domains
mu
st be connected by a Layer 3 device, such as a router or Layer 3 switch. A VLAN is
one type of broadcast domain.



bus

-

The type of circuit used by a computer’s motherboard to transmit data to
components. Most new Pentium computers use buses capable of exch
anging 32 or 64 bits
of data. As the number of bits of data a bus handles increases, so too does the speed of
the device attached to the bus.



CardBus

-

A PCMCIA standard that specifies a 32
-
bit interface running at 33 MHz,
similar to the PCI expansion boar
d standard. Most modern laptops are equipped with
CardBus slots for connecting external modems and NICs, among other things.



CMOS (complementary metal oxide semiconductor)

-

A type of microchip that
requires very little energy to operate. In a PC, the CMOS

stores settings pertaining to a
computer’s devices, among other things.



CompactFlash

-

The standard for an ultrasmall removable data and input/output device
capable of connecting many kinds of external peripherals to workstations, PDAs, and
other computer
ized devices. CompactFlash was designed by the CompactFlash
Association (CFA), a consortium of computer manufacturers.



complementary metal oxide semiconductor

-

See

CMOS.



content switch

-

A switch that provides functions between Layer 4 and Layer 7 of the
OSI model.



convergence time

-

The time it takes for a router to recognize a best path in the event of
a change or network outage.



cut
-
through mode

-

A switching mode in which a switch reads a frame’s header and
decides where to forward the data before it r
eceives the entire packet. Cut
-
through mode
is faster, but less accurate, than the other switching method, store
-
and
-
forward mode.



data port

-

A port on a connectivity device to which network nodes are connected.



device driver

-

The software that enables a
n attached device to communicate with the
computer’s operating system.


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distance
-
vector

-

The simplest type of routing protocols, these determine the best route
for data based on the distance to a destination. Some distance
-
vector routing protocols,
like R
IP, only factor in the number of hops to the destination, while others take into
account latency and other network traffic characteristics.



driver

-

See

device driver.



dynamic routing

-

A method of routing that automatically calculates the best path
betwee
n two nodes and accumulates this information in a routing table. If congestion or
failures affect the network, a router using dynamic routing can detect the problems and
reroute data through a different path. Modern networks primarily use dynamic routing.



EEPROM (electrically erasable programmable read
-
only memory)

-

A type of ROM
that is found on a circuit board and whose configuration information can be erased and
rewritten through electrical pulses.



EIGRP (Enhanced Interior Gateway Routing Protocol)

-

A
routing protocol
developed in the mid
-
1980s by Cisco Systems that has a fast convergence time and a low
network overhead, but is easier to configure and less CPU
-
intensive than OSPF. EIGRP
also offers the benefits of supporting multiple protocols and limit
ing unnecessary
network traffic between routers.



electrically erasable programmable read
-
only memory

-

See

EEPROM.



Enhanced Interior Gateway Routing Protocol

-

See

EIGRP.



expansion board

-

A circuit board used to connect a device to a computer’s
motherboar
d.



expansion card

-

See

expansion board.



expansion slot

-

A receptacle on a computer’s motherboard that contains multiple
electrical contacts into which an expansion board can be inserted.



ExpressCard

-

A PCMCIA standard that allows external devices to con
nect to portable
computers through a 26
-
pin interface, with data transfer rates of 250 Mbps in each
direction (for a total of 500 Mbps), similar to the PCI Express expansion board
specification. ExpressCard modules come in two sizes: 34 mm and 54 mm wide.
Over
time, PCMCIA expects the ExpressCard standard to replace the CardBus standard.



exterior router

-

A router that directs data between nodes outside a given autonomous
LAN, for example, routers used on the Internet’s backbone.



filtering database

-

A coll
ection of data created and used by a bridge that correlates the
MAC addresses of connected workstations with their locations. A filtering database is
also known as a forwarding table.



firewall

-

A device (either a router or a computer running special softw
are) that
selectively filters or blocks traffic between networks. Firewalls are commonly used to
improve data security.



FireWire

-

A peripheral bus standard developed by Apple Computer and codified by the
IEEE as the IEEE 1394 standard. Traditional FireWir
e connections support a maximum
throughput of 400 Mbps, but a newer version supports potential throughput rates of over
3 Gbps. In addition to connecting peripherals, FireWire can be used to network
computers directly in a bus fashion.



firmware

-

A combina
tion of hardware and software. The hardware component of
firmware is a ROM (read
-
only memory) chip that stores data established at the factory
and possibly changed by configuration programs that can write to ROM.



forwarding table

-

See

filtering database.

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gateway

-

A combination of networking hardware and software that connects two
dissimilar kinds of networks. Gateways perform connectivity, session management, and
data translation, so they must operate at multiple layers of the OSI model.



gateway router

-

See

border router.



hub

-

A connectivity device that retransmits incoming data signals to its multiple ports.
Typically, hubs contain one uplink port, which is used to connect to a network’s
backbone.



IEEE 1394

-

See

FireWire.



Industry Standard Architecture

-

See

ISA.



intelligent hub

-

A hub that possesses processing capabilities and can therefore monitor
network traffic, detect packet errors and collisions, poll connected devices for
information, and gather the data in database format.



interior router

-

A
router that directs data between nodes on an autonomous LAN.



Intermediate System to Intermediate System

-

See

IS
-
IS.



interrupt

-

A circuit board wire through which a device issues voltage, thereby signaling
a request for the processor’s attention.



interrup
t request

-

See

IRQ.



IRQ (interrupt request)

-

A message sent to the computer that instructs it to stop what it
is doing and pay attention to something else. IRQ is often used (informally) to refer to the
interrupt request number.



IRQ number

-

The unique n
umber assigned to each interrupt in a computer. Interrupt
request numbers range from 0 to 15, and many PC devices reserve specific numbers for
their use alone.



IS
-
IS (Intermediate System to Intermediate System)

-

A link
-
state routing protocol
that uses a b
est
-
path algorithm similar to OSPF’s. IS
-
IS was originally codified by ISO,
which referred to routers as “intermediate systems,” thus the protocol’s name. Unlike
OSPF, IS
-
IS is designed for use on interior routers only.



ISA (Industry Standard Architecture)

-

The original PC bus type, developed in the
early 1980s to support an 8
-
bit and later a 16
-
bit data path and a 4.77
-
MHz clock speed.



Layer 3 switch

-

A switch capable of interpreting data at Layer 3 (Network layer) of the
OSI model.



Layer 4 switch

-

A sw
itch capable of interpreting data at Layer 4 (Transport layer) of the
OSI model.



link
-
state
-

A type of routing protocol that enables routers across a network to share
information, after which each router can independently map the network and determine
th
e best path between itself and a packet’s destination node.



loopback adapter

-

See

loopback plug.



loopback plug

-

A connector used for troubleshooting that plugs into a port (for example,
a serial, parallel, or RJ
-
45 port) and crosses over the transmit lin
e to the receive line,
allowing outgoing signals to be redirected back into the computer for testing.



main bus

-

See

bus.



managed hub

-

See

intelligent hub.



memory range

-

A hexadecimal number that indicates the area of memory that the NIC
and CPU will use

for exchanging, or buffering, data. As with IRQs, some memory ranges
are reserved for specific devices
-

most notably, the motherboard.



modular router

-

A router with multiple slots that can hold different interface cards or
other devices so as to provide

flexible, customizable network interoperability.

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th

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-
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on
-
board NIC

-

A NIC that is integrated into a computer’s motherboard, rather than
connected via an expansion slot or peripheral bus.



on
-
board port

-

A port that is integrated into a computer’s motherboard.



Open Shortest Path First

-

See

OSPF.



OSPF (Open Shortest Path First)

-

A routing protocol that makes up for some of the
limitations of RIP and can coexist with RIP on a network.



passive hub

-

A hub that simply retransmits signals over the network.



PC Card

-

A PCMCIA standard that specifies a 16
-
bit interface running at 8 MHz for
externally attached devices. PC Cards’ characteristics match those of the ISA expansion
card. And like the ISA standard, the PC Card standard suffered from its lower data
transfer
rates, compared to other PCMCIA standards.



PCI (Peripheral Component Interconnect)

-

A 32 or 64
-
bit bus that can run at 33 or 66
MHz, introduced in its original form in the 1990s. The PCI bus is the NIC connection
type used for nearly all new PCs. It’s cha
racterized by a shorter length than ISA or EISA
cards, but has a much faster data transmission capability.



PCIe (PCI Express)

-

A 32
-

or 64
-
bit bus standard capable of transferring data at up to
4.26 Gbps in full
-
duplex transmission. PCI Express was introd
uced in 2002 and offers
several advantages over traditional PCI. Its expansion cards can fit into older PCI slots,
with some modifications to the motherboard.



PCI Express

-

See

PCIe



PCMCIA (Personal Computer Memory Card International Association)

-

A group

of computer manufacturers who developed an interface for connecting any type of device
to a portable computer. PCMCIA slots may hold memory, modem, network interface,
external hard disk, or CD
-
ROM cards. PCMCIA
-
standard cards include PC Card,
CardBus, and

the newest, ExpressCard.



Peripheral Component Interconnect

-

See

PCI.



Personal Computer Memory Card International Association

-

See

PCMCIA.



Rapid Spanning Tree Protocol

-

See

RSTP.



RIP (Routing Information Protocol)

-

The oldest routing protocol that is s
till widely
used, RIP does not work in very large network environments in which data may have to
travel through more than 15 routers to reach their destination (for example, on the
Internet). And, compared to other routing protocols, RIP is slower and less

secure.



RIPv2 (Routing Information Protocol version 2)

-

An updated version of the original
RIP routing protocol which makes up for some of its predecessor’s overhead and security
flaws. However, RIPv2’s packet forwarding is still limited to a maximum 15
hops.



root bridge

-

The single bridge on a network selected by the Spanning Tree Protocol to
provide the basis for all subsequent path calculations.



router

-

A multiport device that operates at Layer 3 of the OSI model and uses logical
addressing informati
on to direct data between networks or segments. Routers can connect
dissimilar LANs and WANs running at different transmission speeds and using a variety
of Network layer protocols. They determine the best path between nodes based on traffic
congestion, av
ailable versus unavailable routes, load balancing targets, and other factors.



Routing Information Protocol

-

See

RIP.



Routing Information Protocol Version 2

-

See

RIPv2.



routing protocols

-

The means by which routers communicate with each other about
netwo
rk status. Routing protocols determine the best path for data to take between nodes.



routing switch

-

See

Layer 3 switch.

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th

Edition


6
-
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RSTP (Rapid Spanning Tree Protocol)

-

As described in IEEE’s 802.1w standard, a
newer version of the Spanning Tree Protocol that can d
etect and correct for network
changes much more quickly.



runt

-

An erroneously shortened packet.



Spanning Tree Protocol

-

See

STP.



stand
-
alone hub

-

A type of hub that serves a workgroup of computers that are separate
from the rest of the network, also kno
wn as a workgroup hub.



static routing

-

A technique in which a network administrator programs a router to use
specific paths between nodes. Because it does not account for occasional network
congestion, failed connections, or device moves, static routing i
s not optimal.



store
-
and
-
forward mode

-

A method of switching in which a switch reads the entire
data frame into its memory and checks it for accuracy before transmitting it. Although
this method is more time consuming than the cut
-
through method, it allow
s store
-
and
-
forward switches to transmit data more accurately.



STP (Spanning Tree Protocol)

-

A switching protocol defined in IEEE 802.1D. STP
operates in the Data Link layer to prevent traffic loops by calculating paths that avoid
potential loops and by a
rtificially blocking links that would complete a loop. Given
changes to a network’s links or devices, STP recalculates its paths.



switch

-

A connectivity device that logically subdivides a network into smaller,
individual collision domains. A switch operat
es at the Data Link layer of the OSI model
and can interpret MAC address information to determine whether to filter (discard) or
forward packets it receives.



system bus

-

See

bus.



trunking

-

The aggregation of multiple logical connections in one physical c
onnection
between connectivity devices. In the case of VLANs, trunking allows data from multiple
VLANs to share a single interface on a switch.



uplink port

-

A port on a connectivity device, such as a hub or switch, used to connect it
to another connectiv
ity device.



USB (universal serial bus) port

-

A standard external bus that can be used to connect
multiple types of peripherals, including modems, mice, and NICs, to a computer. Two
USB standards exist: USB 1.1 and USB 2.0. USB 3.0 promises to be released
soon. Most
modern computers support the USB 2.0 standard.



virtual local area network

-

See

VLAN.



VLAN (virtual local area network)

-

A network within a network that is logically
defined by grouping its devices’ switch ports in the same broadcast domain. A
VLAN
can consist of any type of network node in any geographic location and can incorporate
nodes connected to different switches.



workgroup hub

-

See

stand
-
alone hub.