network management(2).ppt
TRANSCRIPT
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Network ManagementConcepts and Practice
Author: J. Richard Burke
Presentation by ShuPing !in
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"ut#ine
Network Components
"$er$iew o% Network Management
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Communication Architecture
A communication architecture integrates
many protoco#s and the so%tware that
imp#ements them. &hese parts can be de$e#oped
independent#y o% one another as #ong as the
de$e#opers adhere to the standard
inter%aces between them.
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"S' Re%erence Mode#
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"S' Re%erence Mode#
&he mode# does not speci%y how to imp#ementthe %unction in each #ayer.
&he %unctions in each #ayer are de%ined byprotoco#( which are imp#emented in so%tware. &he so%tware in each #ayer pro$ides ser$ices
to the #ayer abo$e it.
!ayering concept simp#i%ies the de$e#opmentprocess and a##ows impro$ements o% so%twarein one #ayer without a%%ecting other #ayers.
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Physica# !ayer
&his #ayer de%ines the e#ectrica#( mechanica#(
%unctiona# speci%ications %or hardware that
connects a de$ice to the network. Physica# #ayer standards wou#d speci%y
Connector)s si*e and shape
+,act number o% pins &he signa#s that can be used to those
pins
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-ata !ink !ayer
&his #ayer speci%ies the procedures in order
to achie$e re#iab#e pointtopoint trans%er o%
in%ormation between two de$ices. -ata #ink #ayer can be di$ided into two
sub#ayers.
!ogica# !ink Contro#
Medium Access Contro#
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-ata !ink !ayer cont)d/
CSMA0C- is imp#emented in +thernet.
CSMA means that a computer waits unti#
there is no signa# %rom any other computeron !AN be%ore transmitting a message.
C- reduces the probabi#ity that a co##ision
wi## occur by backo%% its transmission.
Bridge is a typica# de$ice working on data
#ink #ayer.
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Network !ayer
&his #ayer pro$ides the mechanisms %or
transporting a packet %rom the source
networks to the destination network. Packets are messages constructed by the
network #ayer and higher #ayers.
A router is ca##ed a network #ayer de$ice
because it is contro##ed by protoco#s up to
and inc#uding the network #ayer.
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&ransport !ayer
&ransport #ayer pro$ides reliableand
unreliabletransport protoco#s.
&he re#iab#e protoco#( which is ca##ed the&ransport Contro# Protoco# &CP/( pro$ides
the mechanisms that enab#e endtoend
re#iabi#ity.
&CP accomp#ishes this by the use o%
automated acknow#edgement and
automated retransmissions.
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&ransport !ayer cont)d/
&he unre#iab#e transport protoco#( which is
ca##ed the 1ser -atagram Protoco# 1-P/(
p#aces no constrains on the network. Beste%%ort de#i$ery %rom the source de$ice to
the destination de$ice is a## that is re2uired.
1-P is used when speed is o% the essence
and the e%%ort spent on ensuring re#iabi#ity is
not coste%%ecti$e.
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Session !ayer
&he Session #ayer pro$ides the mechanisms
necessary to open and c#ose mu#tip#e #ogica#
connections between processes on di%%erentPCs.
&hese #ogica# connections are ca##ed
session.
Many #ogica# connections can use the same
physica# connection.
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Presentation !ayer
&his #ayer pro$ides a commonrepresentation o% data trans%erred betweenpeer app#ication #ayer entities on di%%erentstations.
Abstract synta, notation.one ASN.3/ %ormatis use%u# %or app#ication #ayer.
4owe$er( the #ayers be#ow the presentation#ayer use a %ormant ca## trans%er synta,. &he presentation #ayer trans#ates between
ASN.3 and trans%er synta,.
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App#ication !ayer
Common App#ication Ser$ice +#ements
pro$ide ser$ice genera##y use%u# to a $ariety
o% app#ication programs pro$ided by$endors.
Speci%ic App#ication Ser$ice +#ements
ser$ice the additiona# needs o% particu#ar
app#ication programs.
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5rames
5rame construction App#ication program makes a re2uest.
&he re2uest is passed to the appropriateapp#ication#ayerentity.
&he app#ication#ayerentity constructs anApp#ication #ayer protoco# data unit P-1/.
&he App#ication #ayer P-1 is then passedto the appropriate presentation#ayerentity. &his entity constructs aPresentation #ayer P-1.
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5rames cont)d/
P-1s continue to be constructed and
passed to the #ayers be#ow. &his process
continues unti# the Network #ayer P-1 isrecei$ed by the -ata !ink #ayer.
&he %rame is construct in the -ata !ink
#ayer. &he Network !ayer P-1 is
encapsu#ated in a -ata !ink #ayer headerand trai#er.
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5rames cont)d/
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&CP0'P Protoco# Stack
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6orkstations
6orkstations typica# make use o% the
ser$ices o% a## #ayers o% a protoco# stack
because they process the re2uests o%app#ication programs %or in%ormation on
ser$ers.
Ser$er is #ike workstation making use o% a##
#ayers o% the protoco# stack.
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Repeater
Repeater amp#i%ies the signa# between
segments and e,tends the #ength o% a !AN.
Repeaters are used on 37BAS+8 and37BAS+9 !ANs.
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4ubs
A hub is a repeater with many input andoutput ports.
+$ery transmission recei$ed by the hub onone port is amp#i%ied and retransmitted outo% a## other ports.
4ub do not e,amine in%ormation in any %ie#d
o% the %rame. Repeaters and hubs are consider a Physica#
#ayer de$ice.
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Bridges
&ransparent bridge di$ides a !AN into segments that use the
same media access contro# speci%icationand it contro#s what tra%%ic is passedbetween segments.
uses bridge tableto #earn which de$ices
are on which segments. &rans#ating bridges connects networks using
di%%erent MAC #ayer speci%ications.
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Bridges cont)d/
+rrors and co##isions that take p#ace on one
segment are not propagated to de$ices on
the other segment. &he use o% switches rather than bridges is
commonp#ace today.
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Switches
A switch is a mu#tiport bridge.
Switches are typica##y con%igured to %orward
incoming %rames to outgoing ports based ondestination MAC addresses associated with
those ports in the switch tab#e.
Switches a#so can be con%igured to drop
%rames based on MAC destination or to
redirect %rames to other MAC address.
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Switches cont)d/
4igher #ayers o% the protoco# stack are now
being imp#emented in switches.
!ayer switch a#so can %unction #ike router.
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Routers
Router reads the Network #ayer header in
packet to %ind the destination network
address and then #ooks up the address inrouting tab#e.
&he routing tableis a #ist o% mappings o%
network addresses to ports that wi## get the
packet to the destination networks by thebest means.
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Routers cont)d/
Routing tab#e
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"ut#ine
Network Components
Overview of Network Management
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Network Management
Jobs o% network management in ear#y day
Attaching PCs and ser$er to a !AN using
Network 'nter%ace Cards N'Cs/ 'nsta##ing protoco# stacks
Con%iguring N'C '0" addresses and interrupts
so as not to con%#ict with other N'C se#ections.
1sing Ping app#ication to ensure that a##de$ices on the network cou#d communicate
with one another
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Network Management cont)d/
Access contro#
&he manager might write a script %or the
ser$er to contro# access to in%ormation onit.
&he script wou#d pro$ide access to dri$es(
%o#ders or %i#es that use or group o% users
needed. 'nsta## a print ser$er to manage the print
;obs %rom each o% the PCs.
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Network Management cont)d/
Network con%iguration
'% the networks were to be di$ided into subnets(
then a bridge wou#d be used to connect them.
&he manager wou#d con%igure a routing tab#e toenab#e connecti$ity according to network
address( subnet address and subnet mask.
5ina##y( insta##ing user app#ications on PCs is
necessary %or inter%acing correct#y with "S.
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Maintenance
A%ter con%iguring primary network
ingredients( here comes the maintenance.
Networkperformanceis not optimi*ed( therewi## be so%tware and hardware %ai#ures and
network resources wi## change.
&he manager is re2uired to make estimates
o% the network capacity.
&here was a need %or minima# security.
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Maintenance cont)d/
New work management has di$ided intospecia#ties nowadays.
Administration Backing up ser$ers Maintaining security 'nsta##ing "S and app#ications
Network engineer Be responsib#e %or the hea#th o% the
network and its a$ai#abi#ity to user.
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NetworkBased Management As network has grown #arger and more
comp#icated( network manager needed to %indmore e%%icient way to determine and contro# thestate o% network.
Some protoco#s cou#d be used by networkmanager to remote#y contro# de$ices. Simp#e Network Management Protoco#
SNMP/ Management 'n%ormation Base M'Bs/ Network Management Systems NMS/
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Network Management Protoco#
Stack
Management Station and Management
Agent.
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Network Management
+,amp#e
Step 3 NMS ca##s %or the ser$ice o% the management process
Step 8
the management process ca## the program theimp#ements network management protoco#.
Step NMP constructs a re2uest packet to the program on
the management agent. Step
At the management station the program that
imp#ements the NMP recei$es the response packet. Step ?
&he management process passes the re2uested$a#ue to the app#ication program.