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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-1

Building a Simple Network

nderst!nding the"ost-to-"ostComm#nic!tions $odel

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-2

Understanding Host-to-HostCommunications

%lder model

& 'ro(riet!ry

&A((lic!tion !nd com)in!tions so*t+!re controlled )y one vendor

St!nd!rds-)!sed model& $#ltivendor so*t+!re

& !yered !((ro!ch

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-

Why a Layered Network Model?

ed#ces com(le/ity

St!nd!rdies inter*!ces

!cilit!tes mod#l!r engineering

ns#res intero(er!)letechnology

Acceler!tes evol#tion

Sim(li*ies te!ching !nd le!rning

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-3

he Se!en Layers o" the #S$ Model

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-4

he Se!en Layers o" the #S$ Model %Cont&'

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-5

he Se!en Layers o" the #S$ Model %Cont&'

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he Se!en Layers o" the #S$ Model %Cont&'

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8/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-6

he Se!en Layers o" the #S$ Model %Cont&'

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9/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-

he Se!en Layers o" the #S$ Model %Cont&'

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10/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-10

he Se!en Layers o" the #S$ Model %Cont&'

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11/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-11

(ata )ncapsulation

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12/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-12

(ata (e-)ncapsulation

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13/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-1

*eer-to-*eer Communication

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14/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-13

De*ines *o#r l!yers

ses di**erent n!mes *or !yers 1thro#gh

Com)ines !yers 4 thro#gh 7 intosingle !((lic!tion l!yer

C*+$* Stack

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15/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-14

C*+$* Stack !s& the #S$ Model

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16/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-15

Summary

8he %SI re*erence model de*ines the net+or9 *#nctions th!t occ#r!t e!ch l!yer.

8he (hysic!l l!yer de*ines the electric!l, mech!nic!l, (roced#r!l,!nd *#nction!l s(eci*ic!tions *or !ctiv!ting, m!int!ining, !nd

de!ctiv!ting the (hysic!l lin9 )et+een end systems.

8he d!t! lin9 l!yer de*ines ho+ d!t! is *orm!tted *or tr!nsmission!nd ho+ !ccess to the (hysic!l medi! is controlled.

8he net+or9 l!yer (rovides connectivity !nd (!th selection)et+een t+o host systems th!t m!y )e loc!ted on geogr!(hic!llyse(!r!ted net+or9s.

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17/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-17

Summary %Cont&'

8he tr!ns(ort l!yer segments d!t! *rom the system o* the sendinghost !nd re!ssem)les the d!t! into ! d!t! stre!m on the systemo* the receiving host.

8he session l!yer est!)lishes, m!n!ges, !nd termin!tes sessions

)et+een t+o comm#nic!ting hosts.

8he (resent!tion l!yer ens#res th!t the in*orm!tion sent !t the!((lic!tion l!yer o* one system is re!d!)le )y the !((lic!tionl!yer o* !nother system.

8he !((lic!tion l!yer (rovides net+or9 services to the!((lic!tions o* the #ser, s#ch !s e-m!il, *ile tr!ns*er, !nd termin!lem#l!tion.

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18/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-16

Summary %Cont&'

8he in*orm!tion sent on ! net+or9 is re*erred to !s d!t! or d!t!(!c9ets. I* one com(#ter +!nts to send d!t! to !nother com(#ter,the d!t! m#st *irst )e (!c9!ged )y ! (rocess c!lledenc!(s#l!tion.

:hen the remote device receives ! se;#ence o* )its, the (hysic!ll!yer !t the remote device (!sses the )its to the d!t! lin9 l!yer *orm!ni(#l!tion. 8his (rocess is re*erred to !s de-enc!(s#l!tion.

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19/20 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-1

Summary %Cont&'

8C'

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