Network Hardware, Switching, and Routing

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Network+ Guide to Networks, 6
th

Edition


6
-
1





Chapter
6


Network Hardware
, Switching
,

and Routing



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, 6
th

Edition


6
-
2




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. So
me 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,
bri
dges, and routers
-

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



Chapter Objectives


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



Identify the functions of LAN connectivity hardware



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



Ex
plain 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 transceiver
.


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 NI
Cs smarter than ever.


5.

Emphasize that NICs do not analyze information added by the protocols in Layers 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 inst
alling a NIC.


2.

Describe dependencies of
NICs.


3.

Explain that NICs vary in the following ways:

a.

Access method (for example, Ethernet)

b.

Network transmission speed (for example, 100 Mbps versus 1 Gbps)

c.

Connector interfaces (for example, RJ
-
45 versus SC)

d.

Number
of connector interfaces, or ports

e.

Method of interfacing with the computer’s motherboard (for example, on
-
board,
expansion slot, or peripheral) and interface standard (for example, PCIe or USB)

f.

Manufacturer (popular NIC manufacturers include 3Com, Adaptec,
D
-
Link, IBM,
Intel, Kingston, Linksys, Netgear, SMC, and Western Digital, to name just a few)

g.

Support for enhanced features, such as PoE, buffering, or traffic management


4.

Introduce the
Internal Bus Standards category of NICs
that are installed on an expan
sion
board inside a computer.


5.

Define and describe the term bus.


6.

Define and describe the term expansion slot.


7.

Define and describe the term expansion card
.


8.

Point out that multiple bus types exist.


9.

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


10.

Introduce and describe the PCI bus

type
.


11.

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


12.

Intr
oduce and describe the PCIe bus type.


13.

Describe 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
-
1

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 motherboard with multiple expansion slots.


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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 (Personal Computer Memory C
ard International

Association)

b.

USB (universal serial bus)

c.

CompactFlash

d.

FireWire (IEEE 1394)


20.

Explain

the Personal Computer Memory Card International Association
’s

role in setting
standards for peripheral

devices.

a.

PC C
ard

b.

CardBus

c.

ExpressCard


21.

Describe the peripheral PCMCIA standard called
PC Card
.


22.

Describe the peripheral PCMCIA standard called CardBus.


23.

Describe the peripheral PCMCIA standard called ExpressC
ard
.


24.

Introduce and describe the
USB

peripheral bus standard.


25.

Introduce and describe t
he Firewire peripheral bus standard.


26.

Introduce and describe the CompactFlash peripheral bus standard.


27.

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


28.

Introduce and describe the wireless peripheral bus standard.


Teaching

Tip



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




Teaching

Tip


Students may find 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





Network+ Guide to Networks, 6
th

Edition


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Installing
and Configuring
NICs


1.

Describe the three general steps to install a NIC:

a.

Install NIC hardware

b.

Install NIC software

c.

Configure NIC


2.

Explain how to install and configure expansion card NIC
hardware.


3.

Use Figure 6
-
4

to illustrate a properly installed NIC.


4.

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


5.

Explain how to install and configure expansion card NIC software.


6.

Define the term device driver.


7.

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


8.

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


9.

Emphasize that i
f the op
erating system cannot find a driv
er for the new hardware
,

the
driver will ha
ve to be installed and configured using NIC software and the operating
system interface.


10.

Explain h
ow

to install NIC software from a Windows
7

interface.


11.

Use Figure 6
-
5

to illustrate the Windows Network Connection

dialog box.


12.

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


13.

Define and explain CMOS.


14.

Define and explain BIOS.


15.

Introduce and explain firmware settings.


16.

Explain how to change firmware.

Include a discussion on configuration the NIC
configuration utility.


17.

Describe how to perform diagnostics with the NIC configuration utility.

a.

Define and describe a loopback plug,

b.

Describe a loopback test.



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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LLhomest
ore⹣isc漮oomLen
-
畳L灲潤uctsLlinksys
-
潴her
-
a摡灴ers彳tcsscatf搵㔲〶㝖s癩ewcat.桴m




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.

data 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
been saved to a ROM.

Answer:
F
irmware


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



Modular Interfaces


1.

Explain the advantages of using a
modular interface for a network interface.


2.

Define and describe a GBIC.


3.

Define and describe the SFP GBIC.


4.

Use Figures 6
-
7 and 6
-
8 to illustrate a copper and fiber optic GBIC.



Network+ Guide to Networks, 6
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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.

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


5.

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://homestore.cisco.com/en
-
us/products/linksys_stcVVcatI
d551966VVviewcat.htm




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
-
1
0

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 discover the destination address for each packet it handles.


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://hom
estore.cisco.com/Linksys
-
Powerline_stcVVcatId554690VVviewcat.htm




Switches


1.

Define and describe switches.


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2.

Emph
asize why switches can
interpret MAC address information.


3.

Note the components within switches.


4.

Discuss multiport switches and their
advantages over a bridge.


5.

Use Figure 6
-
1
1

to illustrate
switches
.


6.

Discuss how switches
have been

used historically.


7.

Describe the disadvantages of switches
,

noting that some network administrators have
replaced backbone routers with switches
.


Switch
Installation


1.

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


2.

Review the general steps for installing a switch.


3.

Use Figure 6
-
1
2

to illustrate how to connect a workstation to a switch.


4.

Use Figure 6
-
1
3

to illustrate a switch on a small

network
.


Switching Methods


1.

Introduce switching methods.


2.

Define and describe the cut
-
through mode switching method.


3.

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


4.

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


5.

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


Teaching

Tip



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

http://homestore.cisco.com/en
-
us/products/linksys
-
other
-
routers_stcVVcatId552066VVviewcat.htm



Teaching

Tip



Students may find more information on how switches work at
:

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




Network+ Guide to Networks, 6
th

Edition


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VLANs and Trunking


1.

Define a VLAN (virtual local area networks).


2.

Define the t
erm broadcast domain.


3.

Define the term collision domain and contrast it with a broadcast domain.


4.

Use Figure 6
-
14

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
-
15

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_tech_note09186a0080
094c52.shtml




STP (Spanning Tree Protocol)


1.

Introduce and define STP (Spanning Tree Protocol).


2.

Use Figure 6
-
17

to illustrate an enterprise
-
wide switched network requiring STP.


3.

Review the three steps STP performs.


4.

Use Figure 6
-
18

to illustrate STP
-
selected paths on a switched network.


5.

Review the history of STP.


6.

Discuss the newer protocol as well as the propriet
ary protocols.

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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
distinguishing factors between L
ayer

3 and Layer 4 switches are manufacturer
dependent.


6.

Discuss higher layer switches and their use.



Rout
ers


1.

Define and describe a router.


Router Characteristics and Functions


1.

Explain the
strength of
routers.


2.

Emphasize that routers 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.


6.

Use Figure 6
-
19

to illustrate
three routers.


7.

Describe the tasks performed by routers.


8.

Describe the optional functions a router may contain.


9.

Describe the two methods of d
irecting network traffic:

a.

Static routing

b.

Dynamic routing


10.

Describe the installation characteristics of small networks and large networks.


11.

Use Figure 6
-
2
0

to illustrate
the placement of routers on a LAN
.

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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.

Explain 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 pr
otocol
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.


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

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3.

Switches that operate anywhere between 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.

Wireless technol
ogy is widely deployed in the modern network. Have students discuss
some of the most recent changes or developments in the wireless networking field and the
impact of those changes on the network overall. For example, is it necessary to
potentially reengin
eer parts of the network to support a migration to more wireless or
wire
-
free type of network?


2.

Many students
will

most likely have a small home network or know someone who does.
Have student describe the 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.




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 cos
t,
a
nd
a summary of the
manufacturer specifications.


2.

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

including sections on: Introduction, Background and
H
istory, Technical
S
pecifications, Implementati
on, Barriers, and Summary.



Additional Resources


1.

PCMCIA Official
W
eb

site

http://www.pcmcia.org/


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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 Trun
king

http://www.ciscopress.com/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 other things, bridging and STP
(Spanning

Tree Protocol).



802.1q

The IEEE standard that specifies how VLAN and trunking information appear in

frames and how switc
hes and bridges interpret that information.



802.1w

The IEEE standard that describes RSTP (Rapid Spanning Tree Protocol), which

evolved from STP (Spanning Tree Protocol).



access port

The interface on a switch used for an end node. Devices connected to access

ports are unaware of VLAN information.



application switch

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

OSI model.



backplane

A synonym for motherboard, often

used in the context of switches and

routers.



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. However,

when traffic congestion, segment fa
ilures, and other factors create obstacles, the most
direct

path might not be the best path.



BGP (Border Gateway Protocol)

A distance
-
vector routing protocol capable of
considering

many factors in its routing metrics. BGP, an Exterior Gateway Protocol, is
the routing

protocol used on Internet backbones.



BID (Bridge ID)

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.



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 for
ward 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.

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Bridge ID

See BID.



bus

The type of circ
uit used by a computer’s motherboard to transmit data to
components.

Most new Pentium computers use buses capable of exchanging 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 th
e bus.



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.



cost

In the context of routing metrics
, the value assigned to a particular route as judged
by

the network administrator. The more desirable the path, the lower its cost.



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.



device driver

The software that enables an attached device to communicate with the

computer’s operating system.



distance
-
vect
or

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

RIP, only factor in the number of hops to the destination, while others take into accoun
t

latency and other network traffic characteristics.



driver

See device driver.



dynamic routing

A method of routing that automatically calculates the best path
between

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.



EGP (Exterior Gateway Protocol)

A routing protocol that can span multiple,
autonomous

netwo
rks. BGP and EIGRP are examples of Exterior Gateway Protocols.



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 c
onfigure and less CPU
-
intensive than OSPF. EIGRP also
offers

the benefits of supporting multiple protocols and limiting unnecessary network
traffic

between routers.



Enhanced Interior Gateway Routing Protocol

See EIGRP.



ethtool

A popular tool for viewing an
d modifying network interface properties on Linux

computers.



expansion board

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



expansion card

See expansion board.



expansion slot

A receptacle on a computer’s motherboard that contains mul
tiple
electrical

contacts into which an expansion board can be inserted.



Exterior Gateway Protocol

See EGP.



exterior router

A router that directs data between nodes outside a given autonomous

LAN, for example, routers used on the Internet’s backbone.



filte
ring database

A collection 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 run
ning special software) that selectively

filters or blocks traffic between networks. Firewalls are commonly used to improve data
security.

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forwarding table

See filtering database.



gateway

A combination of networking hardware and software that connects two

d
issimilar 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.



GBIC (Gigabit interface converter)

A standard type of modular
interface designed in
the

1990s for Gigabit Ethernet connections. GBICs may contain RJ
-
45 or fiber
-
optic
cable

ports (such as LC, SC, or ST). They are inserted into a socket on a connectivity
device’s

backplane.



Gigabit interface converter

See GBIC.



hot
-
swappable

The feature of a component that allows it to be installed or removed

without disrupting operations.



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.



IGP (Interior Gateway Protocol)

A routing protocol, such as RIP, that can only route
data

within an autonomous (internal) network.



interior router

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



Intermedi
ate System to Intermediate System

See IS
-
IS.



Interior Gateway Protocol

See IGP.



IS
-
IS (Intermediate System to Intermediate System)

A link
-
state routing protocol that
uses

a best
-
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.



Layer 3 switch

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

model.



Layer 4 switch

A swi
tch 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
the

be
st 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 line to the

receive line,
allowing

outgoing signals to be redirected back into the computer for testing.



main bus

See bus.



mini GBIC

See SFP.



on
-
board NIC

A NIC that is integrated into a computer’s motherboard, rather than

connected via an expansion slot or periphera
l 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.



PCIe

(PCI Component Interconnect Express)

A 32
-
bit bus standard capable of
transferring

data at up to 1 Gbps per data path, or lane, in full
-
duplex transmission. PCIe
is commonly used

for expansion board NICs.



PCI Component Interconnect Express

See PCIe.



Rapid

Spanning Tree Protocol

See RSTP.

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RIP (Routing Information Protocol)

The oldest routing protocol that is still widely
used,

RIP is a distance
-
vector protocol that uses hop count as its routing metric and
allows up to

only 15 hops. It is considered an IGP.
Compared with other, more modern,
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 f
laws.

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 oper
ates at Layer 3 of the OSI model and uses logical

addressing information 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, available versus unavailable routes, load balancing targets, and other factors.



Routing Information Protocol

See RIP.



Routing Information Protocol version 2

See RIPv2.



routing metric

The method used by routing protocols to determine the best path for data

to follow over a network. Routing metrics may be calculated using any of several
variables,

including number of hops, bandwidth, delay, MTU, cost, and load.



routing protocols

The means by which routers communicate with each other about

network status. Routing protocols determine the best path for data to take between nodes.



routing switch

See Layer 3 switch.



routing table

A database stored in a router’s memory that maintains i
nformation about

the location of hosts and best paths for forwarding packets to them.



RSTP (Rapid Spanning Tree Protocol)

As described in IEEE’s 802.1w standard, a
version of

the Spanning Tree Protocol that can detect and correct for network changes
much m
ore quickly.



runt

An erroneously shortened packet.



SFP (small form
-
factor pluggable)
transceiver A standard hot
-
swappable network
interface

used to link a connectivity device’s backplane with fiber
-
optic or copper
cabling. SFPs are known

as mini GBICs beca
use they perform a similar function as
GBICs, but have a smaller profile.

Current SFP standards enable them to send and
receive data at up to 10 Gbps.



SFP GBIC

See SFP.



Spanning Tree Protocol

See STP.



static routing

A technique in which a network administr
ator programs a router to use

specific paths between nodes. Because it does not account for occasional network

congestion, failed connections, or device moves and requires manual configuration, static

routing is 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 allows store
-
and
-
forward

switches to transmit data mo
re 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 artificially blocking links that would complete a l
oop. Given
changes to a network’s

links or devices, STP recalculates its paths.

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switch

A connectivity device that logically subdivides a network into smaller, individual

collision domains. A switch operates at the Data Link layer of the OSI model and can

i
nterpret MAC address information to determine whether to filter (discard) or forward

packets it receives.



system bus

See bus.



trunk port

The interface on a switch capable of managing traffic from multiple VLANs.



trunking

The aggregation of multiple logical

connections in one physical connection

between connectivity devices. In the case of VLANs, a trunk allows two switches to
manage

and exchange data between multiple VLANs.



uplink port

A port on a connectivity device, such as a hub or switch, used to connec
t it
to

another connectivity device.



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 t
ype of network node in any geographic location and can incorporate
nodes connected

to different switches.



VLAN trunking protocol

See VTP.



VTP (VLAN trunking protocol)

Cisco’s protocol for exchanging VLAN information
over

trunks. VTP allows one switch on a
network to centrally manage all VLANs.