chapter 1 - exploration_lan_switching.pptx

7/23/2019 Chapter 1 - Exploration_LAN_Switching.pptx

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LAN DesignLAN Switching and Wireless - Chapter 1

Dr. Naveen Chilamkurti


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Objectives

Describe how a hierarchical network supports the

voice video and data needs o! a small and

medium-si"ed business. #atch the appropriate Cisco switch to each la$er

in the hierarchical network design model.


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Hierarchical Network Model

When building a LAN that satis!ies the needs o! a small- or

medium-si"ed business $our plan is more likel$ to be success!ul i!

a hierarchical design model is used. %ierarchical network design involves dividing the network into discrete

la$ers. &ach la$er provides speci!ic !unctions that de!ine its role within the overall

network.

'$ separating the various !unctions that e(ist on a network the network

design becomes modular which !acilitates scalabilit$ and per!ormance.

)he t$pical hierarchical design model is broken up in to three la$ers* Access

Distribution

Core


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Hierarchical Model - Access Layer

)he access la$er inter!aces with end devices such as +Cs printers and ,+ phonesto provide access to the rest o! the network.

)he access la$er can include routers switches bridges hubs and wireless accesspoints.

)he main purpose o! the access la$er is to provide a means o! connecting devices

to the network and controlling which devices are allowed to communicate on thenetwork.


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Hierarchical Model - Distribution Layer

)he distribution la$er aggregates the data received !rom the

access la$er switches be!ore it is transmitted to the core

la$er !or routing to its !inal destination.

)he distribution la$er controls the !low o! network tra!!ic

using policies and delineates broadcast domains. b$

per!orming routing !unctions between virtual LANs

LANs/ de!ined at the access la$er.

LANs allow $ou to segment the tra!!ic on a switch into

separate subnetworks.Distribution la$er switches are t$picall$ high-per!ormance

devices that have high availabilit$ and redundanc$ to ensure

reliabilit$.


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Hierarchical Model - Distribution Layer


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Hierarchical Model - Core Layer

)he core la$er o! the hierarchical design is the high-

speed backbone o! the internetwork.

)he core la$er is critical !or interconnectivit$

between distribution la$er devices

)he core aggregates the tra!!ic !rom all the

distribution la$er devices so it must be capable o!

!orwarding large amounts o! data 0uickl$.


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Hierarchical Model - Core Layer


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Logical La$out )his logical representation makes it eas$ to see which switches per!orm

which !unction. ,t is much harder to see these hierarchical la$ers when the network is

installed in a business.


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+h$sical La$out )he !igure shows two !loors o! a building.

)he user computers and network devices that need network access are on one !loor.

)he resources such as e-mail servers and database servers are located on another !loor. )o ensure that each !loor has access to the network access la$er and distribution switches are

installed in the wiring closets o! each !loor and connected to each o! the devices needing networkaccess. )he access la$er switch and distribution la$er switch are stacked one on top o! each other in the

wiring closet.


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Beneits o a Hierarchical Network


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Scalabilit$ )he modularit$ o! the design allows $ou to replicate design

elements as the network grows.

'ecause each instance o! the module is consistent e(pansionis eas$ to plan and implement.

or e(ample i! $our design model consists o! two

distribution la$er switches !or ever$ 12 access la$er switches

$ou can continue to add access la$er switches until $ou have12 access la$er switches cross-connected to the two

distribution la$er switches be!ore $ou need to add additional

distribution la$er switches to the network topolog$.


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3edundanc$4ou can dramaticall$ increase availabilit$ through eas$

redundant implementations with hierarchical networks.Access la$er switches are connected to two di!!erent

distribution la$er switches to ensure path redundanc$.Additionall$ distribution la$er switches are connected

to two or more core la$er switches to ensure pathavailabilit$ i! a core switch !ails.

)he onl$ la$er where redundanc$ is limited is at the

access la$er.


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+er!ormanceData is sent through aggregated switch port links

!rom the access la$er to the distribution la$er at nearwire speed in most cases.

)he distribution la$er then uses its high per!ormance

switching capabilities to !orward the tra!!ic up to the

core where it is routed to its !inal destination.As a result properl$ designed hierarchical networks

can achieve near wire speed between all devices.


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Securit$ Access la$er switches can be con!igured with various

port securit$ options that provide control over which

devices are allowed to connect to the network. Some access la$er switches support La$er 5

!unctionalit$ but it is usuall$ the 6ob o! the distribution

la$er switches to process La$er 5 data because the$ can

process it much more e!!icientl$.


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#anageabilit$&ach la$er o! the hierarchical design per!orms

speci!ic !unctions that are consistent throughout

that la$er.Deplo$ment o! new switches is also simpli!ied

because switch con!igurations can be copied

between devices with ver$ !ew modi!ications.Consistenc$ between the switches at each la$er

allows !or rapid recover$ and simpli!ied

troubleshooting.


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#aintainabilit$ ,n some network design models there is a !inite

limit to how large the network can grow be!ore it

becomes too complicated and e(pensive to maintain.or a !ull mesh network topolog$ to achieve

ma(imum per!ormance all switches need to be

high-per!ormance switches because each switchneeds to be capable o! per!orming all the !unctions

on the network.


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!rinci"les o Hierarchical Network Design

+rinciples o! %ierarchical Network Design Network Diameter

'andwidth Aggregation 3edundanc$


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Network DiameterNetwork diameter is the number o! devices that a

packet has to cross be!ore it reaches its

destination. ,n the three-la$er hierarchical model La$er 7

segmentation at the distribution la$er practicall$

eliminates network diameter as an issue.


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'andwidth Aggregation

'andwidth aggregation is the practice o! considering

the speci!ic bandwidth re0uirements o! each part o!

the hierarch$.A!ter bandwidth re0uirements o! the network are

known links between speci!ic switches can be

aggregated which is called link aggregation.

Link aggregation allows multiple switch port links to

be combined so as to achieve higher throughput

between switches.


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3edundanc$3edundanc$ is one part o! creating a highl$ available

network.

3edundanc$ can be provided in a number o! wa$s. or e(ample $ou can double up the network connections between devices or $ou

can double the devices themselves.

,mplementing redundant links can be e(pensive. ,magine i! ever$ switch had a connection to ever$ switch at the ne(t la$er.

,t is unlikel$ that $ou will be able to implement redundanc$ at the access la$er

because o! the cost and limited !eatures in the end devices.


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#hat is a Converged Network$

Convergence is the process o! combining voice andvideo communications on a data network.

Legac$ &0uipment

#ost telephone companies toda$ have made the transition to digital-based

switches. %owever there are man$ o!!ices that still use analog phones so the$still have e(isting analog telephone wiring closets.

Advanced )echnolog$

#oving to a converged network can be a di!!icult decision i! the business

alread$ invested in separate voice video and data networks.

8ne bene!it o! a converged network is that there is 6ust one network tomanage.


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New 8ptions 4ou can now tie voice and video communications directl$ into an emplo$ee9s

personal computer s$stem.

)here is no need !or an e(pensive handset phone or videocon!erencing e0uipment.

So!tphones such as the Cisco ,+ Communicator o!!er a lot o! !le(ibilit$ !or

businesses.

With the addition o! ine(pensive webcams videocon!erencing can be added to a

so!tphone.


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Separate oice ideo and Data Networksoice network

A voice network contains isolated phone lines running to a +': switch to

allow phone connectivit$ to the +S)N.

When a new phone is added a new line has to be run back to the +':.)he +': switch is t$picall$ located in a )elco wiring closet separate

!rom the data and video wiring closets.


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ideo network ideocon!erencing data can consume signi!icant bandwidth on a

network. As a result video networks were maintained separatel$ to

allow the videocon!erencing e0uipment to operate at !ull speed

without competing !or bandwidth with voice and data streams.


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Data network)he data network interconnects the workstations and

servers on a network to !acilitate resource sharing.Now that properl$ designed hierarchical networks can accommodate the

bandwidth re0uirements o! voice video and data communications at thesame time it makes sense to converge them all onto a single hierarchicalnetwork.


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Considerations or Hierarchical Network %witches

)ra!!ic low Anal$sis )ra!!ic !low anal$sis is the process o! measuring the

bandwidth usage on a network.

)o select the appropriate switch !or a la$er in ahierarchical network $ou need to have speci!ications that

detail the target tra!!ic !lows user communities data

servers and data storage servers.

Anal$"ing the various tra!!ic sources and their impact onthe network allows $ou to more accuratel$ tune and

upgrade the network to achieve the best possible

per!ormance.


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;ser Communities Anal$sis ;ser communit$ anal$sis is the process o! identi!$ing various groupings o!

users and their impact on network per!ormance.


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;ser Communities Anal$sis )he location o! the user communities in!luences where data stores and

server !arms are located.


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uture


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Data Stores and Data Servers Anal$sisWhen anal$"ing tra!!ic on a network consider where

the data stores and servers are located so that $ou can

determine the impact o! tra!!ic on the network. When considering the tra!!ic !or data stores and

servers consider both client-server tra!!ic and server-

server tra!!ic.


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Data Stores and Data Servers Anal$sis Client-server tra!!icis the tra!!ic generated when a client device accesses data

!rom data stores or servers.

Client-server tra!!ic t$picall$ traverses multiple switches to reach its destination.

'andwidth aggregation and switch !orwarding rates are important !actors toconsider when attempting to eliminate bottlenecks !or this t$pe o! tra!!ic.

Client-%erver Co&&unication


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%erver-server traicis the tra!!ic generated between data storage devices on

the network.

Some server applications generate ver$ high volumes o! tra!!ic between data stores

and other servers.

)o optimi"e server-server tra!!ic servers needing !re0uent access to certain

resources should be located in close pro(imit$ to each

%erver-%erver Co&&unication


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)opolog$ Diagrams A topolog$ diagram is a graphical representation o! a network

in!rastructure.

A topolog$ diagram shows how all switches are interconnected

detailed down to which switch port interconnects the devices. A topolog$ diagram graphicall$ displa$s an$ redundant paths or

aggregated ports between switches that provide !or resilienc$ and

per!ormance.

)opolog$ diagrams can also contain in!ormation about device

densities and user communities.

%aving a topolog$ diagram allows $ou to visuall$ identi!$ potential

bottlenecks in network tra!!ic


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)opolog$ DiagramsA network topolog$ can be ver$ di!!icult to piece together a!terthe !act i! $ou were not part o! the design process.

Network cables in the wiring closets disappear into the !loors

and ceilings making it di!!icult to trace their destinations.

And because devices are spread throughout the building it is

di!!icult to know how all o! the pieces are connected together.

With patience $ou can determine 6ust how ever$thing is

interconnected and then document the network in!rastructure

in a topolog$ diagram.


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%witch 'eatures

Switch orm actorsWhen $ou are selecting a switch $ou need to decide

between i(ed con!iguration

#odular con!iguration Stackable Non-stackable.Another consideration is the thicknesso! the switch

e(pressed in number o! rack units. or e(ample the i(ed Con!iguration Switches shown in the!igure are all 1;.


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%witch 'eatures

i(ed Con!iguration Switches i(ed con!iguration switches means is that $ou cannot add !eatures or

options to the switch be$ond those that originall$ came with the

switch.

)here are t$picall$ di!!erent con!iguration choices that var$ in how

man$ and what t$pes o! ports are included.


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%witch 'eatures

#odular Switches #odular switches t$picall$ come with di!!erent si"ed chassis that allow !or

the installation o! di!!erent numbers o! modular line cards.

)he line cards actuall$ contain the ports.

)he line card !its into the switch chassis like e(pansion cards !it into a +C.

)he larger the chassis the more modules it can support.


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%witch 'eatures

Stackable Switches Stackable switches can be interconnected using a special

backplane cable that provides high-bandwidth throughput

between the switches.

)he stacked switches e!!ectivel$ operate as a single larger

switch.

Stackable switches are desirable where !ault tolerance and

bandwidth availabilit$ are critical


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%witch 'eatures

+er!ormance When selecting a switch !or the access( distribution( or core layers

consider the abilit$ o! the switch to support the

+ort densit$

orwarding rates'andwidth aggregation


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%witch 'eatures

!ort Density +ort densit$ is the number o! ports available on a single

switch.

i(ed con!iguration switches t$picall$ support up to => ports

on a single switch.

#odular switches can support ver$ high port densities

through the addition o! multiple switch port line cards


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%witch 'eatures

orwarding 3ates orwarding rates de!ine the processing capabilities

o! a switch b$ rating how much data the switch canprocess per second.


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%witch 'eatures

Link AggregationAs part o! bandwidth aggregation $ou should determine i! there

are enough ports on a switch to aggregate to support the re0uired

bandwidth.


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%witch 'eatures

+ower over &thernet +ower over &thernet +o&/ allows the switch to deliver power

to a device over the e(isting &thernet cabling. +o& allows $ou more !le(ibilit$ when installing wireless access points and ,+

phones because $ou can install them an$where $ou can run an &thernet cable.


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%witch 'eatures

La$er 5 unctions La$er 5 switches o!!er advanced !unctionalit$ that will route tra!!ic in la$er 5 ,+

address.

La$er 5 switches are also known as multila$er switches.

)$picall$ switches operate at La$er 7 o! the 8S, re!erence model where the$ deal primaril$

with the #AC addresses o! devices connected to switch ports.


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%witch 'eatures in a Hierarchical Network

Access La$er Switch eaturesAccess layer switches acilitate the connection o end node

devices to the network)

)he$ need to support !eatures such as*!ort security*allows the switch to decide how man$ or what

speci!ic devices are allowed to connect to the switch.

+LANs* Access la$er switches allow $ou to set the LANs

!or the end node devices on $our network.!ort s"eed* ast &thernet allows up to 122 #b?s o! tra!!ic

per switch port.


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Access La$er Switch eatures !o,*,t should onl$ be considered when voice convergence is

re0uired or wireless access points are being implemented and

power is di!!icult or e(pensive to run to the desired location.

Link aggregation*Access la$er switches take advantage o!

link aggregation when aggregating bandwidth up to

distribution la$er.

o%* ,n a converged network supporting voice video and data

network tra!!ic access la$er switches need to support @oS to

maintain the prioriti"ation o! tra!!ic.

% i i i i


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Distribution La$er Switch eatures Distribution layer switches collect the data ro& all the access layer

switches and orward it to the core layer switches)

)he$ need to support !eatures such as

%u""ort Layer . unctions* Distribution la$er switches provides theinter-LAN routing !unctions so that one LAN can communicate with

another on the network.

%ecurity !olicies* Access lists are used to control how tra!!ic !lowsthrough the network.

uality o %ervice* )he distribution la$er switches need to support@oS to maintain the prioriti"ation o! tra!!ic coming !rom the access la$er

switches that have implemented @oS.

% i h ' i Hi hi l N k


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Distribution La$er Switch eatures

/edundancy*,t is important that distribution switches

support redundanc$ !or ade0uate availabilit$.

Link aggregation* )$picall$ access la$er switches use

multiple links to connect to a distribution la$er switch to

ensure ade0uate bandwidth to accommodate the tra!!ic

generated on the access la$er and provide !ault tolerance in

case a link is lost.


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Core La$er Switch eatures )he core la$er o! a hierarchical topolog$ is the high-speed

backbone o! the network and re0uires switches that can

handle ver$ high !orwarding rates. )he$ need to support !eatures such as

Link Aggregation*)he core la$er also needs to ensure

ade0uate bandwidth coming into the core !rom the distribution

la$er switches.

/edundancy* La$er 5 redundanc$ t$picall$ has a !aster

convergence than La$er 7 redundanc$ in the event o!

hardware !ailure.

o%* An important services provided b$ core la$er switches.


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'or %&all and Mediu& %i0ed Business 1%MB2

Cisco has seven switch product lines. &ach product line o!!ersdi!!erent characteristics and !eatures allowing $ou to !ind the rightswitch to meet the !unctional re0uirements o! $our network.

)he Cisco switch product lines are* Catal$st &(press 22

Catal$st 7B2 Catal$st 52 Catal$st 52 Catal$st =22 Catal$st =B22 Catal$st 22


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)he Catal$st &(press 22 is Cisco9s entr$-la$er switch. ,t o!!ers*orwarding rates !rom >.>


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)he Catal$st 7B2 series switches enable entr$-la$er enterprise

medium-si"ed and branch o!!ice networks to provide enhanced

LAN services.

)he Catal$st 7B2 series switches o!!ers the !ollowing*orwarding rates !rom 1


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)he Cisco Catal$st 52 series is a line o! enterprise-class switches that

include support !or +o& @oS and advanced securit$ !eatures such as ACLs. )hese switches are ideal access la$er switches !or small enterprise LAN access

or branch-o!!ice converged network environments. )he Cisco Catal$st 52 Series supports !orwarding rates o! 57

ports with .5 watts

Catalyst 3560


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)he Cisco Catal$st 52 series o! switches are ideal !or access

la$er switches in midsi"e organi"ations and enterprise branch

o!!ices.

)his series o!!ers !orwarding rates !rom 57 ports with .5 watts

Catalyst 3750


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)he Catal$st =22 is the !irst midrange modular switching plat!orm o!!ering

multila$er switching !or enterprises small- to medium-si"ed businesses and

service providers. With !orwarding rates up to 15 = ast &thernet or


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)he Catal$st =B22 series switches are designed and

optimi"ed !or server switching b$ allowing ver$ high

!orwarding rates.

)his switch series supports dual redundant power suppliesand !ans that can be swapped out while the switch is still

running. )his allows the switches to achieve higher

availabilit$ which is critical in data center deplo$ments.

)he Catal$st =B22 series switches support advanced @oS!eatures making them ideal candidates !or the back-end ,+

telephon$ hardware.

Catalyst 4900


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)he Catal$st 22 series modular switch is optimi"ed !or secure

converged voice video and data networks. )he Catal$st 22 series is the highest per!orming Cisco switch

supporting !orwarding rates up to 72 27.5a! Class 5 1.=W/ +o& devices

;p to 117 12?122 ports 12?122?1222 ports =12 S+


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Tony Chen COD

Cisco Networking Academy

%u&&ary

%ierarchical Design model addresses per!ormance

scalabilit$ maintainabilit$ F manageabilit$ issues. )ra!!ic Anal$sis is used to monitor network per!ormance. %ierarchical Design #odel is composed o! 5 la$ers*

Access

Distribution

Core

Switches selected !or each la$er must meet the needs o!

each hierarchical la$er as well as the needs o! the business.

chapter 1 - exploration_lan_switching.pptx

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