6d Computer Networking IP Address

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________________________________________________________ _____

Application Note ________________________________________________________ _____

IP AddressingA Simplified Tutorial

July 2002 Avaya LabsCOMPAS ID 92962



1



All information in tis !o"um#nt is sub$#"t to "an%# &itout noti"#'

Altou% t# information is b#li#v#! to b# a""urat#( it is )rovi!#! &itout%uarant## of "om)l#t# a""ura"y an! &itout &arranty of any *in!' It is t#

us#r+s r#s)onsibility to v#rify an! t#st all information in tis !o"um#nt'

Avaya sall not b# liabl# for any a!v#rs# out"om#s r#sultin% from t#

a))li"ation of tis !o"um#nt, t# us#r must ta*# full r#s)onsibility'



2



Companion document

- LA.s an! /LA.s A Sim)lifi#! utorial

tt)&&&1'avaya'"om#nt#r)ris#&it#)a)#rsvlan3tutorial')!f



4



Introduction

# )ur)os# of tis tutorial is to %iv# t# n#&"om#r to !atan#t&or*in% a basi" un!#rstan!in% of IP a!!r#ssin%' # follo&in% to)i"sar# "ov#r#!'

5 IP a!!r#ssin% fun!am#ntals

5 Classful IP a!!r#ssin% 5 Subn#t mas*s

5 /ariabl# l#n%t subn#t mas*s /LSM7

5 Classl#ss int#r3!omain routin% CID87

5 8outin% an! routin% )roto"ols



IP Addressing Fundamentals



:



OSI and TCP/IP

OSI 8#f#r#n"# 1CP2IP #rms us#! in tis tutorialMo!#l

; 5 A))li"ation

6 5 Pr#s#ntation A))li"ation: 5 S#ssion

5 rans)ort <ost 5 to 5 <ost CP )ort( =DP )ort61CP2=DP7

4 5 .#t&or* Int#rn#t 6IP7 IP address2 5 Data Lin* .#t&or* Int#rfa"# MAC a!!r#ss

1 5 Pysi"al

1• is tabl# is )r#s#nt#! for r#f#r#n"# )ur)os#s'

5 # first "olumn so&s t# ;3lay#r OSI 8#f#r#n"# Mo!#l( &i" is a mo!#lus#! to !#si%n )roto"ols tat ma*# n#t&or*in% )ossibl#'

5 # s#"on! "olumn so&s t# CPIP )roto"ol sta"* in r#f#r#n"# to t# OSImo!#l' CPIP is t# )r#val#nt )roto"ol sta"* for !ata n#t&or*in%'

5 # tir! "olumn so&s tat an IP a!!r#ss is a lay#r 4 L47 a!!r#ss( as &#llas its r#lationsi) to t# MAC a!!r#ss an! CP=DP )ort( &i" ar# not

"ov#r#! in tis tutorial'



6



Anatomy of an IP address

1• # IP a!!r#ss is a 423bit a!!r#ss tat "onsists of t&o "om)on#nts'

2• On# "om)on#nt is t# n#t&or* )ortion of t# a!!r#ss( "onsistin% of t#n#t&or* bits'

5 # n#t&or* bits ma*# u) t# l#ft )ortion of t# a!!r#ss'

5 #y "onsist of t# first bit u) to som# boun!ary( to b# !is"uss#! lat#r'

3• # s#"on! "om)on#nt is t# ost )ortion of t# a!!r#ss( "onsistin%of t# ost bits'

5 # ost bits ma*# u) t# ri%t )ortion of t# a!!r#ss'

5 #y "onsist of t# r#mainin% bits not in"lu!#! &it t# n#t&or* bits'



;



The mask

1• # n#t&or* )ortion of t# a!!r#ss is s#)arat#! from t# ost )ortionof t# a!!r#ss by a mas*'

2• # mas* sim)ly in!i"at#s o& many bits ar# us#! for t# n#t&or*)ortion( l#avin% t# r#mainin% bits for t# ost )ortion'

3• A 23bit mas* in!i"at#s tat t# first 2 bits of t# a!!r#ss ar# n#t&or*bits( an! t# r#mainin% > bits ar# ost bits'

4• A 163bit mas* in!i"at#s tat t# first 16 bits of t# a!!r#ss ar# n#t&or*bits( an! t# r#mainin% 16 bits ar# ost bits'

5• An! so fort?

6• # !iff#r#n"# b#t&##n a n#t&or* mas* an! a subn#t mas* &ill b##@)lain#! as tis tutorial )ro%r#ss#s'



>



uick lesson in !inary math1• inary mat is bas#! on )o&#rs of 2( as o))os#! to )o&#rs of 10 for

!#"imal mat' 5 B#r#as !#"imal mat as a 1s )la"#( 10s )la"#( 100s )la"#( an! so fort?

5 inary mat as a 1s )la"#( 2s )la"#( s )la"#( >s )la"#( an! so fort'

2• iv#n an o"t#t > bits7( &#n a bit in t# o"t#t is s#t 17 its valu# is?

5 12> l#ft3most bit most si%nifi"ant bit7 2;

5 6 n#@t bit 26

5 42 n#@t bit 2:

5 16 n#@t bit 2

5 > n#@t bit 24

5 n#@t bit 22

5 2 n#@t bit 21

5 1 ri%t3most bit l#ast si%nifi"ant bit7 20

3• B#n a bit in an o"t#t is not s#t 07 its valu# is E#ro'4• # !#"imal valu# of an o"t#t is t# sum of #a" s#t bit+s valu#'

5 11000000 12> F 6 192

5 10101000 12> F 42 F > 16>

5 11111111 12> F 6 F 42 F 16 F > F F 2 F 1 2::



9



"otted decimal notation

1• Ma"in#s r#a! t# IP a!!r#ss as a str#am of 42 bits'

2• <o&#v#r( for uman "onsum)tion( t# IP a!!r#ss is &ritt#n in !ott#!!#"imal notation'

5 # 423bit a!!r#ss is !ivi!#! into %rou)s of > bits an o"t#t or a byt#7' 5 Ga" o"t#t is &ritt#n as a !#"imal numb#r ran%in% from 0 to 2::'

5 # !#"imal numb#rs ar# s#)arat#! by )#rio!s( or !ots'



10



Net#ork$ host$ and !roadcast addresses

1• Hor a %iv#n IP n#t&or*?

5 t# n#t&or* bits r#main fi@#! an! t# ost bits vary'

5 t# n#t&or* a!!r#ss is t# on# tat r#sults &#n all t# ost bits ar# not s#tt# r#sult of )#rformin% an A.D o)#ration on t# a!!r#ss an! its mas*7'

5 t# broa!"ast a!!r#ss is t# on# tat r#sults &#n all t# ost bits ar# s#t'

5 ost a!!r#ss#s ar# tos# tat r#sult &it all r#mainin% "ombinations of t#ost bits'

2• # n#@t t&o sli!#s so& #@am)l#s of o& to !#t#rmin# t# variousa!!r#ss#s for t&o n#t&or*s'



11



%&'!it mask (%))*%))*%))*+,



12



-.'!it mask (%))*%))*+*+,



14



Significance of IP net#orks and hosts

1• An IP ost is any !#vi"# &it an IP a!!r#ss( su" as a PC'

2• Multi)l# osts r#si!# on a %iv#n IP n#t&or* or subn#t sort for subn#t&or*7' Subn#ts &ill b# !is"uss#! lat#r'

3• A %rou) of IP n#t&or*s is an int#rn#t&or*( &it t# lar%#st int#rn#t&or*b#in% t# Int#rn#t'

4• Bat is ty)i"ally "all#! a !ata n#t&or* is t#"ni"ally an int#rn#t&or*(

b#"aus# multi)l# IP n#t&or*s ar# "onn#"t#! to%#t#r by rout#rs'

1• is int#rn#t&or* "ontains 6 IP n#t&or*s'

2• .ot# tat #v#n a lin* b#t&##n rout#rs is a n#t&or*'



1



Physical net#ork s* IP net#ork

1•

In t#rms of )ysi"al"onn#"tivity( it is "ommonto s## t#s# t#rms us#!'# t#rm n#t&or* #r#

!#s"rib#s as a &ol# t#"onn#"t#! !#vi"#s tatma*# u) tis !ata

n#t&or*'

- o b# mor# )r#"is#(t#s# t#rms ar# us#! to

!#s"rib# )ysi"al"onn#"tivity'

- Ga" )ysi"al s#%m#ntas a s#)arat# lo%i"alIP n#t&or* or subn#t'



1:



Formula to determine num!er of hosts onn aa gien net#ork

1• iv#n tat t#r# ar# . ost bits in an a!!r#ss( t# numb#r of osts for

tat n#t&or* is 2. 3 2' &o a!!r#ss#s ar# subtra"t#! for t# n#t&or*

a!!r#ss an! t# broa!"ast a!!r#ss'

2• > ost bits 2> 3 2 2: osts

3• 16 ost bits 216

3 2 6::4 osts

4• 2 ost bits 22

3 2 16;;;21 osts

5• As tis tutorial )ro%r#ss#s( it &ill b#"om# a))ar#nt o& n#t&or*s ar#ty)i"ally siE#! so tat t#r# is a mana%#abl# numb#r of osts'



16



Pu!lic addresses

1• Most IP a!!r#ss#s ar# )ubli" a!!r#ss#s' Publi" a!!r#ss#s ar# r#%ist#r#!

as b#lon%in% to a s)#"ifi" or%aniEation'

2• Int#rn#t S#rvi"# Provi!#rs ISP7 an! #@tr#m#ly lar%# or%aniEations in t#='S' obtain blo"*s of )ubli" a!!r#ss#s from t# Am#ri"an 8#%istry for

Int#rn#t .umb#rs A8I. tt)&&&'arin'n#t7' Ot#r or%aniEations obtain)ubli" a!!r#ss#s from t#ir ISPs'

3• #r# ar# A8I. "ount#r)arts in ot#r )arts of t# &orl!( an! all of t#s#r#%ional r#%istration autoriti#s ar# sub$#"t to t# %lobal Int#rn#t Assi%n#!.umb#rs Autority IA.A tt)&&&'iana'or%7'

4• Publi" IP a!!r#ss#s ar# rout#! a"ross t# Int#rn#t( so tat osts &it)ubli" a!!r#ss#s may fr##ly "ommuni"at# &it on# anot#r %lobally'

5• .o or%aniEation is )#rmitt#! us# )ubli" a!!r#ss#s tat ar# not r#%ist#r#!&it tat or%aniEationK



1;



Priate addresses1• 8HC 191> !#si%nat#s t# follo&in% as )rivat# a!!r#ss#s'

5 Class A ran%# 10'0'0'0 trou% 10'2::'2::'2::' 5 Class ran%# 1;2'16'0'0 trou% 1;2'41'2::'2::'

5 Class C ran%# 192'16>'0'0 trou% 192'16>'2::'2::'

2• Privat# a!!r#ss#s may b# us#! by any or%aniEation( &itoutany r#uir#m#nt for r#%istration'

3• #"aus# )rivat# a!!r#ss#s ar# ambi%uous 3 "an+t t#ll &#r# t#y+r#"omin% from or %oin% to b#"aus# anyon# "an us# t#m 3 )rivat#a!!r#ss#s ar# not )#rmitt#! to b# rout#! a"ross t# Int#rn#t'

4• ISPs blo"* )rivat# a!!r#ss#s from b#in% rout#! a"rosst#ir infrastru"tur#'

5• .ot# # us# of )rivat# a!!r#ss#s( n#t&or* a!!r#ss translation .A7( an! )ro@y

s#rv#rs solv#! t# IP a!!r#ss sorta%# )robl#m for t# sort an! m#!ium t#rms'# )ro$#"t#! lon%3t#rm solution is IPv6' #s# to)i"s &ill not b# !is"uss#! #r#'



1>



Classful IP Addressing and its Shortcomingsmings



19



Three main classes

1• Class A n#t&or*s

5 Hirst o"t#t valu#s ran%# from - through -%.'

5 Hirst o"t#t starts &it bit +'

5 .#t&or* mas* is 0 !its( &ritt#n /0 or %))*+*+*+'

5 -*+*+*+ through -%.*+*+*+ ar# "lass A n#t&or*s &it -.111%-& osts #a"'

2• Class n#t&or*s

5 Hirst o"t#t valu#s ran%# from -%0 through -2-'

5 Hirst o"t#t starts &it binary )att#rn -+'

5 .#t&or* mas* is -. !its( &ritt#n /-. or %))*%))*+*+'

5 -%0*+*+*+ through -2-*%))*+*+ ar# "lass n#t&or*s( &it .))3& osts #a"'

3•

Class C n#t&or*s 5 Hirst o"t#t valu#s ran%# from -2% through %%3'

5 Hirst o"t#t starts &it binary )att#rn --+'

5 .#t&or* mas* is %& !its( &ritt#n /%& or %))*%))*%))*+'

5 -2%*+*+*+ through %%3*%))*%))*+ ar# "lass C n#t&or*s( &it %)& osts #a"'



20



21



The need to improe IP addressing efficiencyiency

1• As IP n#t&or*in% an! int#rn#t&or*in% )ro%r#ss#!( it b#"am# v#ry

a))ar#nt tat "lass A an! n#t&or*s &#r# sim)ly too lar%#'

2• 2: osts on on# n#t&or* s#%m#nt is mana%#abl#( but 6::4 osts or mor# on a sin%l# n#t&or* s#%m#nt is !iffi"ult to mana%#'

5 is &oul! r#sult in "lass A an! n#t&or*s not b#in% fully utiliE#!( m#anin%tat not all t# ost a!!r#ss#s &oul! %#t us#!'

5 Or it &oul! r#sult in mor# osts b#in% )ut onto a sin%l# n#t&or* s#%m#nt tan

"oul! r#asonably b# mana%#!'

3• Hor t#s# an! ot#r r#asons( t#r# &as a n##! to im)rov# t# #ffi"i#n"y

of IP a!!r#ssin%' at is( to )rovi!# a &ay to limit t# numb#r of osta!!r#ss#s )#r n#t&or* s#%m#nt to &at is a"tually n##!#!( r#%ar!l#ss

of t# n#t&or* "lass'

4• is n##! &as m#t )ro%r#ssiv#ly trou% t# "on"#)tions of subn#tmas*s( variabl#3l#n%t subn#t mas*s( an! "lassl#ss int#r3!omain routin%'



22



Su!net 4asks

24



56tending the classful net#ork mask

1•

Subn#t mas*s ar# us#! to ma*# "lassful n#t&or*s mor# mana%#abl# an!#ffi"i#nt( by "r#atin% small#r subn#ts an! r#!u"in% t# numb#r of osta!!r#ss#s )#r subn#t to &at is a"tually r#uir#!'

2• Subn#t mas*s &#r# first us#! on "lass boun!ari#s'

3• G@am)l#

5 a*# "lass A n#t&or* 10'0'0'0 &it n#t&or* mas* 2::'0'0'0'

5 A!! a!!itional > subn#t bits to n#t&or* mas*' 5 .#& subn#t mas* is 2::'2::'0'0'

5 .#& subn#ts ar# 10'0'0'0( 10'1'0'0( 10'2'0'0( an! so on &it 6::4 osta!!r#ss#s )#r subn#t' Still too many osts )#r subn#t'

4• G@am)l#

5 a*# "lass A n#t&or* 10'0'0'0 &it n#t&or* mas* 2::'0'0'0'

5 A!! a!!itional 16 subn#t bits to n#t&or* mas*' 5 .#& subn#t mas* is 2::'2::'2::'0

5 .#& subn#ts ar# 10'0'0'0( 10'0'1'0( 10'0'2'0( ?( 10'1'0'0( 10'1'1'0( 10'1'2'0(

?( 10'2'0'0( 10'2'1'0( 10'2'2'0( an! so on &it 2: ost a!!r#ss#s )#rsubn#t'



2



Su!netting continued

1• G@am)l# 5 a*# "lass n#t&or* 1;2'16'0'0 &it n#t&or* mas* 2::'2::'0'0'

5 A!! a!!itional > subn#t bits to n#t&or* mas*'

5 .#& subn#t mas* is 2::'2::'2::'0

5 .#& subn#ts ar# 1;2'16'0'0( 1;2'16'1'0( 1;2'16'2'0( an! so on &it 2: osta!!r#ss#s )#r subn#t'

2• As so&n in t#s# #@am)l#s?

5 A "lass A n#t&or* "an b# subn#tt#! to "r#at# 2:6 2>7 16 subn#ts'

5 A "lass A n#t&or* "an b# subn#tt#! to "r#at# 6::46 216

7 2 subn#ts'

5 A "lass n#t&or* "an b# subn#tt#! to "r#at# 2:6 2>7 2 subn#ts'

3• .ot# #"ni"ally t#r# r#ally is no su" tin% as a "lassful subn#t or "lassfulsubn#t mas*' <o&#v#r( t#rms su" as "lass C subn#t an! "lass C subn#tmas* ar# us#! routin#ly to !#s"rib# a "lass A or n#t&or* tat as b##nsubn#tt#! &it a 23bit mas*'



2:



Terminology check

1• y no& it soul! b# a))ar#nt tat t# t#rms n#t&or* an! subn#tt#"ni"ally m#an t&o !iff#r#nt tin%s'

2• <o&#v#r( it is bot "ommon an! som#&at a""#)t#! to us# t# t#rmsint#r"an%#ably in "asual "ommuni"ation'

3• If t#r# is a mor# %#n#ral t#rm of t# t&o( it is n#t&or*'

4• It soul! also b# a))ar#nt by no& tat t# t#rms n#t&or* mas* an!subn#t mas* t#"ni"ally m#an t&o !iff#r#nt tin%s'

5• ut a%ain( it is bot "ommon an! som#&at a""#)t#! to us# t# t#rmsint#r"an%#ably in "asual "ommuni"ation'

6• # t#rm mas* is a %#n#ral t#rm tat is "ommonly us#! b#"aus# of itsambi%uity'

7• # )ro)#r t#rms ar# us#! mor# "onsist#ntly in formal "ommuni"ation'



26



7aria!le'length Su!net 4asks(78S4,



2;



Improing the efficiency of su!net maskss

1• /LSM r#mov#! t# "lass boun!ary r#stri"tion of tra!itional subn#t mas*s'

2• Bit /LSM a n#t&or* of any "lass "an b# subn#tt#! to almost any siE#'

3• # n#@t s#ri#s of sli!#s so&s #@am)l#s of /LSM'



2>



Successie su!nets #/ a %.'!it su!net maskask

1• # n#@t four sli!#s so& a "lass A n#t&or* subn#tt#! &it a 263bitsubn#t mas*'

2• Su""#ssiv# subn#ts ar# so&n, tat is( t# n#t&or* a!!r#ss#s ar#

so&n in s#u#n"#'

3• #s# sli!#s so& tat in t# sam# a!!r#ss s)a"# as a 2 n#t&or* or

subn#t &it 2: ost a!!r#ss#s( four small#r 26 subn#ts "an b# "r#at#!(#a" &it 62 ost a!!r#ss#s'



29



-* %.'!it su!net mask (%))*%))*%))*-2%,



40



%* %.'!it su!net mask (%))*%))*%))*-2%,



41



3* %.'!it su!net mask (%))*%))*%))*-2%,



42



&* %.'!it su!net mask (%))*%))*%))*-2%,



44



Successie su!nets #/ a %3'!it su!net maskask

1• # n#@t four sli!#s so& t# sam# "lass A n#t&or* as in t# )r#vious

sli!#s( but &it a 243bit subn#t mas*'

2• Su""#ssiv# subn#ts ar# so&n, tat is( t# n#t&or* a!!r#ss#s ar#so&n in s#u#n"#'

3•

A 24 subn#t as :10 ost a!!r#ss#s( an! tis is ar%uably t# lar%#stnumb#r of osts to )ra"ti"ally )ut on a LA. s#%m#nt'

5 # n#@t lar%#r subn#t 223bit subn#t mas*7 as 1022 ost a!!r#ss#s'

5 As #@)lain#! in t# "om)anion !o"um#nt( LA.s an! /LA.s A Sim)lifi#!utorial( all IP osts must transmit A8P broa!"asts'

5 In a!!ition( IP osts )arti"i)at# in ot#r #@"an%#s tat r#uir# broa!"asts(an! som# a))li"ations ar# v#ry broa!"ast3int#nsiv#'

5 A tousan! or so osts transmittin% fr#u#nt broa!"asts to all ot#r osts ona LA. s#%m#nt "an b# v#ry ta@in% on n#t&or* an! ost !#vi"#s'

5 #r# ar# also ot#r r#asons( in a!!ition to broa!"asts( &y a tousan!#n!)oints on on# LA. s#%m#nt &oul! not b# !#sirabl#'



4



-* %3'!it su!net mask (%))*%))*%)&*+,



4:



%* %3'!it su!net mask (%))*%))*%)&*+,



46



3* %3'!it su!net mask (%))*%))*%)&*+,



4;



&* %3'!it su!net mask (%))*%))*%)&*+,



4>



Successie su!nets #/ a 3+'!it su!net maskask

1• # n#@t four sli!#s so& t# sam# "lass A n#t&or* as in t# )r#vioussli!#s( but &it a 403bit subn#t mas*'

2• Su""#ssiv# subn#ts ar# so&n, tat is( t# n#t&or* a!!r#ss#s ar#so&n in s#u#n"#'

3• A 40 subn#t as t&o ost a!!r#ss#s( an! tis is t# small#st )#rmissibl#subn#t'

5 A 41 subn#t as only t&o a!!r#ss#s b#"aus# t#r# is only on# ost bit'

5 is &oul! allo& for a n#t&or* a!!r#ss an! a broa!"ast a!!r#ss an! no osta!!r#ss#s'

4• 40 subn#ts ar# "ommonly us#! for )oint3to3)oint lin*s( su" as BA.

lin*s( b#"aus# t#r# ar# only t&o osts on t# n#t&or* s#%m#nt'



49



-* 3+'!it su!net mask (%))*%))*%))*%)%,

0



0



%* 3+'!it su!net mask (%))*%))*%))*%)%,

1



1



3* 3+'!it su!net mask (%))*%))*%))*%)%,

2



2



&* 3+'!it su!net mask (%))*%))*%))*%)%,

4



4



Classless Inter'domain 9outing(CI"9,



Supernetting

1• /#ry sim)ly stat#!( CID8 is "ombinin% t&o or mor# "lassful n#t&or*s to"r#at# a su)#rn#t&or*'

2• # most "ommon us# of CID8 for a"tual a!!r#ssin% is to "ombin#t&o or mor# "lass C n#t&or*s to "r#at# a 24 or 22 su)#rn#t'

3• Hor #@am)l#( t# "lass C n#t&or*s 192'16>'42'0 an! 192'16>'44'0"oul! b# "ombin#! to "r#at# 192'16>'42'024'

4• # "lass C n#t&or*s 192'16>'4'0 an! 192'16>'4:'0 "oul! b# "ombin#!to "r#at# 192'16>'4'024'

5• #s# t&o #@am)l#s ar# illustrat#! in t# follo&in% sli!#s'

:



:



-* Supernet #/ %3'!it mask (%))*%))*%)&**+,+,

6



%* Supernet #/ %3'!it mask (%))*%))*%)&**+,+,

;



CI"9 o!serations

1• #r# r#ally is no si%nifi"ant !iff#r#n"# b#t&##n t# 24 su)#rn#t

#@am)l#s $ust so&n an! t# 24 subn#t #@am)l#s so&n )r#viously' 5 ot n#t&or*s utiliE# t# sam# 243bit mas*'

5 ot n#t&or*s av# :10 ost a!!r#ss#s'

5 # only !iff#r#n"# is tat a "lass A n#t&or* &as subn#tt#! in on# s#t of #@am)l#s( an! t&o "lass C n#t&or*s &#r# su)#rn#tt#! in t# ot#r'

2• As &it all tin%s in IP a!!r#ssin%( su)#rn#ts must fall on bit boun!ari#s'

5 #r# must b# a )o&#r of 2 numb#r 2( ( >( ?7 of n#t&or*s in a su)#rn#t'1• A 24 su)#rn#t must in"lu!# t&o "lass C n#t&or*s'

2• A 22 su)#rn#t must in"lu!# four "lass C n#t&or*s'

5 Hor #@am)l#( it is not )ossibl# to "r#at# a su)#rn#t tat in"lu!#s $ust

192'16>'1'0 an! 192'16>'2'0' o in"lu!# bot t#s# n#t&or*s t# mas* must

b# 22 bits( an! a 223bit mas* must also in"lu!# t# n#t&or*s 192'16>'0'0 an!

192'16>'4'0'

3• Altou% t# t#rm su)#rn#t is us#! in tis tutorial to #@)lain CID8( tis

t#rm is not "ommonly us#! in "asual "ommuni"ation' Inst#a!( most &illsim)ly us# t# t#rm n#t&or*'

>



9outing and 9outing Protocols



9

Th IP h d



The IP header

1• is tutorial &ill not "ov#r t# #ntir# IP #a!#r( but it is )r#s#nt#! #r# for r#f#r#n"#'

2• Hor tis s#"tion it is im)ortant to not# tat #v#ry IP )a"*#t as an IP#a!#r( an! t#r#for# as a sour"# an! !#stination IP a!!r#ss'

5 # sour"# a!!r#ss b#lon%s to t# ost tat ori%inat#! t# IP )a"*#t'

5 # !#stination a!!r#ss b#lon%s to t# ost( or osts if t# )a"*#t is abroa!"ast( tat is to r#"#iv# t# IP )a"*#t'

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:0

IP ti d fi d



IP routing defined

1• IP routin% is t# )ro"#ss of !#liv#rin% IP )a"*#ts from on# IP n#t&or* to

anot#r'

2• 8outin% is t# "or# fun"tion of a rout#r'

5 o for&ar! an IP )a"*#t from on# IP n#t&or* to anot#r( a rout#r must *no&o& to rout# tat )a"*#t to its !#stination'

5 If a rout#r is !ir#"tly "onn#"t#! to a )a"*#t+s !#stination n#t&or*( t# rout#r

"an in!#)#n!#ntly for&ar! t# )a"*#t to tat n#t&or*' 5 If a rout#r is not !ir#"tly "onn#"t#! to a )a"*#t+s !#stination n#t&or*( t# rout#r

must *no& t# n#@t3o) rout#r to &i" t# )a"*#t must b# for&ar!#!'

3• IP osts )arti"i)at# in routin% to a mu" l#ss#r !#%r##'

5 <osts on any %iv#n IP n#t&or* "an in!#)#n!#ntly "ommuni"at# &it on#

anot#r' 5 <osts on !iff#r#nt IP n#t&or*s( o&#v#r( must "ommuni"at# trou% an IP

%at#&ay( or rout#r'

5 A ost must b# a&ar# of its %at#&ay or %at#&ays'

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A t f t



Anatomy of a route

1• In %#n#ral( a rout# "onsists of a !#stination an! a %at#&ay'

2• If a ost or rout#r is only "a)abl# of "lassful routin%( its rout# tabl# &illav# t&o fi#l!s'

!#stination %at#&ay

5 Su" a !#vi"# "an only rout# to "lassful n#t&or*s( usin% t# "lassful n#t&or*mas*'

5 #"aus# t#r# "an b# only on# "lassful n#t&or* mas* bas#! on t#!#stination IP a!!r#ss( t#r# is no n##! to #@)li"itly s)#"ify t# mas*'

1• If a ost or rout#r is "a)abl# of "lassl#ss routin%( its rout# tabl# &ill av#tr## fi#l!s'

!#stination mas* %at#&ay

5 Su" a !#vi"# "an rout# to bot "lassful n#t&or*s an! "lassl#ss subn#ts' 5 is r#uir#s tat a mas* b# #@)li"itly s)#"ifi#!'

1• Most !#vi"#s ar# "a)abl# of "lassl#ss routin%'

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" f lt dd t d t



"efault address$ route$ and gate#ay

1• # !#fault a!!r#ss is 0'0'0'0' is a!!r#ss #n"om)ass#s all IPa!!r#ss#s'

2• # !#fault a!!r#ss is us#! to s)#"ify a !#fault rout#( &i" is t# rout#to b# ta*#n &#n no ot#r mor# s)#"ifi" rout# is availabl#'

3• Hor #@am)l#

!#stination %at#&ay0'0'0'0 a!!r#ss3of3rout#r3on3tis3n#t&or*

!#stination mas* %at#&ay

0'0'0'0 0'0'0'0 a!!r3of3rout#r3on3tis3n#t

1• As so&n #r#( t# mas* for a !#fault rout# is 0'0'0'0'

2• # %at#&ay us#! for t# !#fault rout# is t# !#fault %at#&ay'

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Static routing



Static routing

1• Stati" rout#s ar# manually #nt#r#! into a rout#r or ost'

2• An a!ministrator must *no& t# int#rn#t&or* layout an! t# )ats tat#@ist b#t&##n n#t&or*s'

3• #n t# a!ministrator must )ro%ram #a" rout#r in t# int#rn#t&or* &it

t# )ro)#r rout#s to %#t from any %iv#n n#t&or* to any ot#r n#t&or*'

4• # osts obtain t#ir rout#s manually or via D<CP'

:



"ynamic routing



"ynamic routing

1• Dynami" rout#s ar# rout#s l#arn#! via on# or mor# routin% )roto"ols'

2• 8outin% )roto"ols ar# us#! by rout#rs to inform on# anot#r of t#IP n#t&or*s a""#ssibl# to t#m'

3• #r# ar# "lassful routin% )roto"ols( su" as 8IPv1( tat !o not transmitmas*s in t#ir routin% u)!at#s 3 t# "lassful n#t&or* mas* is im)li#!'

4• #r# ar# also "lassl#ss routin% )roto"ols( su" as OSPH( tat !otransmit mas*s in t#ir routin% u)!at#s'

5• Dynami" routin% is mu" too "om)l#@ a sub$#"t to b# "ov#r#! in tistutorial' Suffi"# it to say tat OSPH is t# most )r#val#nt stan!ar! routin%

)roto"ol to!ay( an! li*#ly t# most )r#val#nt routin% )roto"ol ov#rall'

6• 8outin% )roto"ols ty)i"ally !o not a))ly to osts' <osts obtain t#ir rout#s by manual "onfi%uration or by D<CP'

::



Static s dynamic routing



Static s* dynamic routing

1• On# !iff#r#n"# b#t&##n stati" rout#s an! !ynami" rout#s is tat on# is

#nt#r#! in manually an! t# ot#r is l#arn#! an!or "al"ulat#!!ynami"ally'

2• # bi% !iff#r#ntiator( o&#v#r( is in o& t# rout#rs a!a)t to s)ora!i""an%#s in n#t&or* to)olo%y "aus#! by outa%#s'

3• A stati"ally rout#! n#t&or* as almost no &ay of a!a)tin% to t#m)oraryto)olo%y "an%#s' ut routin% )roto"ols ar# !#si%n#! for tis )ur)os#'

4• A *#y fa"tor in !#si%nin% n#t&or*s an! "oosin% a routin% )roto"ol is"onv#r%#n"# tim#( &i" is t# tim# it ta*#s for t# n#t&or* as a &ol#to !is"ov#r its to)olo%y an! r#a" a st#a!y stat#'

5• In %#n#ral( t# sort#r t# "onv#r%#n"# tim# t# b#tt#r' A n#t&or* tat"onv#r%#s ui"*ly "an b#tt#r "om)#nsat# for un#@)#"t#! outa%#s'

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One last note a!out route ta!les



One last note a!out route ta!les

1• In a!!ition to !#stination( mas*( an! %at#&ay( most rout#rs av# on#

ot#r fi#l! in t#ir rout# tabl#s( &i" &as not )r#viously m#ntion#!'

2• is fi#l! is a sour"# fi#l!( &i" in!i"at#s o& a rout# &as obtain#!(&#t#r stati"ally or by a routin% )roto"ol'

3• Altou% t# sour"# of a rout# is v#ry si%nifi"ant for n#t&or*a!ministration( it is not t# fo"us of tis tutorial'

4• is tutorial is mor# "on"#rn#! &it t# rout# its#lf( an! not n#"#ssarilyo& it &as obtain#!'

:;



9outing e6ample



9outing e6ample

- is #@am)l# a))li#s r#%ar!l#ss of o& t# rout#s &#r# l#arn#!'

:>



9outing analysis



9outing analysis1• <osts P an!

5 <osts P an! av# only on# &ay to %#t off t#ir n#t&or*s( an! tat is to

for&ar! traffi" to t# rout#r "onn#"t#! to t#ir r#s)#"tiv# n#t&or*s' 5 #s# osts #a" av# a !#fault rout# to a !#fault %at#&ay 3 rout#r N or '

2• 8out#r N

5 8out#r N as int#rfa"#s !ir#"tly "onn#"t#! to n#t&or*s A( ( an! C( so it "anrout# traffi" b#t&##n t#s# n#t&or*s &o a!!itional "onfi%urations'

5 is rout#r as only on# o)tion to %#t to ot#r n#t&or*s( an! tat is to for&ar!

traffi" to rout#r ' So it as a !#fault rout# to rout#r '3• 8out#r

5 8out#r as int#rfa"#s !ir#"tly "onn#"t#! to n#t&or*s D( G( an! H( so it "anrout# traffi" b#t&##n t#s# n#t&or*s &o a!!itional "onfi%urations'

5 is rout#r as only on# o)tion to %#t to ot#r n#t&or*s( an! tat is to for&ar!traffi" to rout#r ' So it as a !#fault rout# to rout#r '

4• 8out#r

5 8out#r automati"ally *no&s o& to rout# traffi" b#t&##n n#t&or*s C an! D'

5 o %#t to n#t&or*s A an! ( tis rout#r for&ar!s traffi" to rout#r N'

5 o %#t to n#t&or*s G an! H( tis rout#r for&ar!s traffi" to rout#r '

5 On# of t#s# rout#s "oul! b# ma!# t# !#fault rout#'

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9outing e6ample #ith IP addresses addeded



9outing e6ample #ith IP addresses addeded

- # routin% analysis in t# )r#vious sli!# still a))li#s'

60



9outing o!serations



9outing o!serations

1• In t# )r#"#!in% !ia%ram( t# n#t&or* "oul! not av# &or*#! &it"lassful routin%'

2• Bitout subn#t mas*s( rout#r &oul! av# a rout# to "lass A n#t&or*10'0'0'0 via %at#&ay 1;2'16'0':'

5 is &oul! r#sult in all 10'@'@'@ )a"*#ts( tat trav#rs# rout#r ( b#in%

for&ar!#! to rout#r '

5 Hor #@am)l#( rout#r &oul! for&ar! !#stination 10'20':'@ )a"*#ts to rout#r ( an! rout#r &oul! r#turn t#m to rout#r '

5 is is b#"aus# rout#r as no &ay to !istin%uis b#t&##n 10'20':'0 an!

10'20';'0 &itout a subn#t mas*'

5 D#stination 10'20':'@ )a"*#ts &itin rout#r N 3 tat is( tos# sour"#! from192'16>'2'@ 3 &oul! not b# aff#"t#! by tis )#nom#non'

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9oute summari:ation



9oute summari:ation1• B#r# /LSM an! CID8 b#"om# truly )o&#rful is in rout# summariEation'

2• is #@am)l# so&s 42 in!ivi!ual rout#s b#in% summariE#! to a sin%l#

rout# usin% a 193bit mas*( an! 16 in!ivi!ual rout#s b#in% summariE#! toa sin%l# rout# usin% a 203bit mas*'

3• 8out# summariEation r#sults in %r#at#r routin% #ffi"i#n"y( as #a" rout#a!!s a )ro"#ssor bur!#n to t# rout#r'

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9oute summari:ation analysis



9oute summari:ation analysis

1• # su)#rn#t 192'16>'0'019 mas* 2::'2::'22'07 "ov#rs a!!r#ss#s

trou%

2• Bil# su" a su)#rn#t &oul! not b# )ra"ti"al to s#rvi"# a sin%l# LA.s#%m#nt( a summariE#! rout# to tis su)#rn#t "ov#rs all )ossibl#

a!!r#ss#s in t# 42 in!ivi!ual "lass C n#t&or*s 192'16>'0'02 trou%192'16>'41'02'

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9oute summari:ation analysis continuedd



y

1• # subn#t 10'40'0'020 mas* 2::'2::'20'07 "ov#rs a!!r#ss#s

trou%

2• Bil# su" a subn#t &oul! not b# )ra"ti"al to s#rvi"# a sin%l#

LA. s#%m#nt( a summariE#! rout# to tis subn#t "ov#rs all

)ossibl# a!!r#ss#s in t# 16 in!ivi!ual subn#ts 10'40'0'02trou% 10'40'1:'02'

6



9outes #/ multiple IP gate#ays



p g y

1• is is an #@am)l# of a LA. s#%m#nt tat as t&o IP %at#&ays to t&o!iff#r#nt )arts of t# !ata n#t&or*'

1• In tis "onfi%uration it is )r#f#rabl# tat #a" ost av# t&o !iff#r#ntrout#s 3 a !#fault rout# to t# !#fault %at#&ay( an! a n#t&or* rout# to t#s#"on! %at#&ay'

6:



IC4P 9edirects



1• If t# ost !o#s not av# a n#t&or* rout# to t# s#"on! %at#&ay( it "anl#arn ost rout#s from ICMP 8#!ir#"t m#ssa%#s'

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IC4P 9edirect analysis



1• # rout# l#arn#! via an ICMP 8#!ir#"t m#ssa%# is a ost rout#( &i" isa rout# to an in!ivi!ual ost rat#r tan to a n#t&or* or subn#t'

2• A ost rout# as a 423bit mas* 2::'2::'2::'2::7( &i" m#ans tat allt# bits in t# IP a!!r#ss ar# fi@#!'

5 is ma*#s s#ns# b#"aus# a ty)i"al n#t&or* or subn#t mas* fi@#s t#n#t&or* bits an! allo&s t# ost bits to vary'

5 Bit a 423bit mas* t#r# ar# no bits l#ft to vary( so t# only vali! a!!r#ss &ittis mas* is t# sin%l# a!!r#ss'

5 in*in% alon% t#s# lin#s t# 0'0'0'0 mas* for t# !#fault rout# also ma*#ss#ns#( b#"aus# tis mas* allo&s all t# bits to vary( m#anin% tat #v#rya!!r#ss is in"lu!#! &it tis mas*'

3• In most im)l#m#ntations t# ost rout# l#arn#! via an ICMP 8#!ir#"tm#ssa%# is a t#m)orary rout#' It r#mains in t# rout# tabl# for a f#&minut#s an! t#n tim#s out'

6;



9ecommended reading



1• 8HC 9:0 3 Int#rn#t Stan!ar! Subn#ttin% Pro"#!ur#

2• 8HC 1:19 3 Classl#ss Int#r3Domain 8outin% CID87

3• 8HC 191> 3 A!!r#ss Allo"ation for Privat# Int#rn#ts

6>



Q 2002 Avaya In"' All 8i%ts 8#s#rv#!'

Avaya an! t# Avaya Lo%o ar# tra!#mar*s of Avaya In"' or Avaya GCS

Lt!'( a &olly o&n#! subsi!iary of Avaya In"' an! may b# r#%ist#r#! int# =S an! ot#r $uris!i"tions' All tra!#mar*s i!#ntifi#! by R an! ar#r#%ist#r#! tra!#mar*s or tra!#mar*s( r#s)#"tiv#ly( of Avaya In"' All ot#rr#%ist#r#! tra!#mar*s or tra!#mar*s ar# )ro)#rty of t#ir r#s)#"tiv#o&n#rs'

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6d Computer Networking IP Address

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Transcript of 6d Computer Networking IP Address