Study Sheets - 99drop · Study Sheets INTRO 2 ICND/CCNA 49 0791_SSPDFtoc.copy Page 580 Thursday,...
107
Study Sheets INTRO 2 ICND/CCNA 49
Transcript of Study Sheets - 99drop · Study Sheets INTRO 2 ICND/CCNA 49 0791_SSPDFtoc.copy Page 580 Thursday,...
-
Study Sheets
INTRO 2
ICND/CCNA 49
0791_SSPDFtoc.copy Page 580 Thursday, July 3, 2003 2:44 PM
-
Gra
ph
ic S
ymb
ols
Co
mp
uti
ng
Bas
ics
PC
Co
mp
on
ents
PCs
are
the
build
ing
bloc
ks o
f ne
twor
ks. T
hey
have
man
y of
the
sam
e pa
rts
and
syst
ems
as
othe
r ne
twor
k de
vice
s, s
uch
as r
oute
rs a
nd s
wit
ches
. You
sho
uld
unde
rsta
nd t
he f
unct
ions
of
the
fol
low
ing
com
pone
nts
in c
ase
the
need
to
trou
bles
hoot
ari
ses.
Co
mp
on
ent
Fun
ctio
n
Bus
Wir
es t
hat
conn
ect
the
inte
rnal
com
pone
nts
to t
he
CPU
.
CD
-RO
M d
rive
Com
pact
Dis
c R
ead-
Onl
y M
emor
y.
Cen
tral
Pro
cess
ing
Uni
t (C
PU)
The
com
pute
r’s “
brai
n” w
here
nea
rly
all
calc
ulat
ions
are
per
form
ed.
Exp
ansi
on c
ard
A p
rint
ed c
ircu
it b
oard
tha
t ca
n be
inse
rted
for
ad
diti
onal
fun
ctio
nalit
y.
Exp
ansi
on s
lot
An
open
ing
in t
he c
ompu
ter
for
expa
nsio
n ca
rds.
Sw
itch
Acc
ess
Ser
ver
Brid
geR
oute
r
Net
wor
k S
witc
h
Mul
tilay
erS
witc
h
Hub
Net
wor
k C
loud
or
Bro
adca
st D
omai
n
Pers
onal
Com
pute
rFi
le S
erve
r
WA
N C
loud
Mod
em
Eth
erne
tFa
st E
ther
net
Ser
ial L
ine
Circ
uit S
witc
hed
Line
DS
U/C
SU
Dat
a S
ervi
ce U
nit/
Cha
nnel
Ser
vice
Uni
t
VLA
N
ISD
NS
witc
h
Co
mp
on
ent
Fun
ctio
n
Flop
py d
isk
driv
eA
dev
ice
for
read
ing
and
wri
ting
to
flopp
y di
sks.
Har
d di
sk d
rive
Use
d to
sto
re a
nd r
etri
eve
data
fro
m n
onvo
lati
le
stor
age
med
ia.
Mic
ropr
oces
sor
A s
ilico
n ch
ip t
hat
cont
ains
a C
PU.
Mot
herb
oard
The
com
pute
r’s m
ain
circ
uit
boar
d. E
very
thin
g el
se
plug
s in
to t
he m
othe
rboa
rd a
nd is
con
trol
led
by it
.
Prin
ted
circ
uit
boar
dA
thi
n pl
ate
on w
hich
inte
grat
ed c
ircu
its
are
plac
ed.
Mem
ory
Inte
rnal
sto
rage
.
Ran
dom
Acc
ess
Mem
ory
(RA
M)
A t
empo
rary
sto
rage
pla
ce f
or d
ata
whi
le p
rogr
ams
are
in u
se. I
f th
e co
mpu
ter
lose
s po
wer
, all
data
in
RA
M t
hat
was
not
sav
ed is
lost
.
Rea
d-O
nly
Mem
ory
(RO
M)
Prer
ecor
ded
or “
star
tup”
mem
ory.
Era
sabl
e Pr
ogra
mm
able
Rea
d-O
nly
Mem
ory
(EPR
OM
)C
ompu
ter
mem
ory
unav
aila
ble
to t
he u
ser.
It
usua
lly c
onta
ins
very
bas
ic in
stru
ctio
ns f
or t
he
com
pute
r’s
oper
atio
n.
Syst
em u
nit
The
com
pute
r’s m
ain
“box
.”
Bac
kpla
neA
larg
e ci
rcui
t bo
ard
that
has
soc
kets
for
exp
ansi
on
card
s.
Sock
etA
con
nect
or f
or e
xpan
sion
car
ds.
Inte
rfac
eA
dev
ice
that
con
nect
s to
pie
ces
of e
quip
men
t (a
m
ouse
and
com
pute
r, fo
r ex
ampl
e).
Net
wor
k ca
rdA
PC
B t
hat
prov
ides
net
wor
k ac
cess
.
Para
llel p
ort
An
inte
rfac
e th
at c
omm
unic
ates
mor
e th
an 1
bit
of
info
rmat
ion
at a
tim
e. U
sual
ly u
sed
to c
onne
ct
devi
ces
such
as
prin
ters
.
Seri
al p
ort
An
inte
rfac
e th
at c
an c
omm
unic
ate
1 bi
t at
a t
ime.
Uni
vers
al S
eria
l Bus
(U
SB)
An
inte
rfac
e th
at a
llow
s ot
her
devi
ces
to b
e co
nnec
ted
and
disc
onne
cted
wit
hout
res
etti
ng t
he
syst
em.
0791_fm.book Page 582 Wednesday, July 2, 2003 12:13 PM
-
Lap
top
and
note
book
com
pute
rs a
re s
mal
ler,
mor
e po
rtab
le v
ersi
ons
of P
Cs.
As
chip
inte
-gr
atio
n te
chni
ques
con
tinu
e to
impr
ove,
lapt
ops
are
beco
min
g ev
ery
bit
as f
unct
iona
l as
PCs.
Lap
tops
use
PC
car
d sl
ots
or P
erso
nal C
ompu
ter
Mem
ory
Car
d In
tern
atio
nal A
ssoc
i-at
ion
(PC
MC
IA)
card
slo
ts w
here
cre
dit
card
-siz
e ne
twor
k ca
rds,
mod
ems,
or
hard
dri
ves
can
be a
dded
.N
ICs,
als
o kn
own
as L
AN
ada
pter
s, p
rovi
de n
etw
ork
conn
ectiv
ity fo
r PC
s an
d la
ptop
s. N
ICs
plug
into
the
mot
herb
oard
thro
ugh
an e
xpan
sion
slo
t or
are
pres
olde
red
to it
. NIC
s re
quir
e th
e fo
llow
ing:
•In
terr
upt
Req
uest
Lin
e (I
RQ
)—T
his
sign
al t
ells
the
CPU
tha
t an
eve
nt h
as o
ccur
red
that
req
uire
s pr
oces
sing
.•
I/O
add
ress
—A
mem
ory
loca
tion
whe
re in
stru
ctio
nal d
ata
can
be s
tore
d.•
Dri
vers
—Pr
ogra
m-s
peci
fic in
stru
ctio
ns.
Whe
n se
lect
ing
a N
IC, c
onsi
der
the
follo
win
g:•
Net
wor
k ty
pe—
Eac
h ne
twor
k re
quir
es a
spe
cific
typ
e of
NIC
.•
Med
ium
typ
e—Tw
iste
d pa
ir, c
oaxi
al, w
irel
ess,
and
so
on.
•Sy
stem
bus
—PC
I bu
ses
are
mos
t co
mm
on.
Bit
s, B
ytes
, an
d M
easu
rem
ent
Term
sA
ltho
ugh
a co
mpu
ter
can
mak
e ve
ry c
ompl
icat
ed c
alcu
lati
ons,
the
com
pute
r’s b
rain
use
s si
mpl
e in
stru
ctio
ns c
ompo
sed
of e
lect
roni
c si
gnal
s th
at r
epre
sent
1s
and
0s. A
sys
tem
wit
h on
ly t
wo
stat
es is
cal
led
a bi
nary
sys
tem
. A s
ingl
e st
ate
(a s
ingl
e 1
or a
sin
gle
0) is
cal
led
a bi
t. A
gro
upin
g of
8 b
its
is c
alle
d a
byte
. The
fol
low
ing
tabl
e sh
ows
the
com
mon
uni
ts.
It is
impo
rtan
t to
pay
att
enti
on t
o th
e un
it o
f m
easu
rem
ent.
For
exa
mpl
e, m
any
mod
ems
give
the
ir s
peed
in k
ilobi
ts p
er s
econ
d (k
bps)
, but
man
y pr
ogra
ms
show
dow
nloa
d ti
mes
in
kilo
byte
s pe
r se
cond
(kB
ps).
A m
odem
ope
rati
ng a
t 45
kbp
s do
wnl
oads
at
only
5.7
6 kB
ps
(bes
t ca
se).
Dec
imal
-to
-Bin
ary
Co
nve
rsio
nC
ompu
ters
use
a n
umbe
ring
sys
tem
bas
ed o
n on
ly 1
s an
d 0s
. Thi
s ty
pe o
f sy
stem
is c
alle
d bi
nary
or
base
2. T
his
num
beri
ng s
yste
m m
ight
see
m a
wkw
ard
at fi
rst
glan
ce, b
ut it
use
s th
e sa
me
logi
c as
the
bas
e 10
sys
tem
we
use
ever
y da
y. A
s w
ith
base
10,
bin
ary
coun
ting
st
arts
wit
h th
e “o
nes”
col
umn
unti
l all
the
num
bers
are
exh
aust
ed, a
nd t
hen
it r
olls
ove
r to
th
e ne
xt c
olum
n, w
hich
is a
pow
er o
f th
e ba
se. F
or e
xam
ple,
bas
e 10
has
ten
num
bers
(0
thro
ugh
9). W
hen
coun
ting
, you
sta
rt in
the
“on
es”
colu
mn
and
coun
t un
til y
ou r
each
the
hi
ghes
t un
it. T
hen
you
mov
e to
the
“te
ns”
colu
mn.
Thi
s co
ntin
ues
wit
h su
cces
sive
pow
ers
(1, 1
01, 1
02, 1
03).
The
bin
ary
syst
em’s
colu
mns
or
plac
ehol
ders
are
20 ,
21 ,
22 ,
23 ,
and
so
on. T
he f
ollo
win
g ta
ble
show
s th
e va
lues
for
the
firs
t se
ven
plac
es.
Bin
ary
num
bers
are
use
d ex
tens
ivel
y in
net
wor
king
. The
y ar
e th
e ba
sis
of IP
add
ress
ing.
To
conv
ert
betw
een
deci
mal
and
bin
ary,
it b
est
to b
uild
a s
impl
e ta
ble
like
the
one
just
sho
wn.
To
con
vert
fro
m b
inar
y to
dec
imal
, sim
ply
add
up t
he “
plac
e va
lues
” of
the
dig
its
that
are
1s
. In
the
prec
edin
g ex
ampl
e, t
he p
lace
hold
ers
for
1, 2
, 4, 8
, and
32
all c
onta
in 1
s. A
ddin
g th
ose
valu
es y
ield
s 47
. (10
1111
in b
inar
y is
47
in d
ecim
al.)
To
conv
ert
from
dec
imal
to
bina
ry, a
gain
bui
ld a
tab
le. P
ut a
1 in
the
hig
hest
pla
ce v
alue
(in
thi
s ex
ampl
e, a
1 is
pla
ced
in t
he c
olum
n re
pres
enti
ng 3
2. (
64 c
anno
t be
use
d, b
ecau
se it
is g
reat
er t
han
47.)
Now
sub
-tr
act t
he p
lace
val
ue fr
om th
e de
cim
al n
umbe
r (4
7-32
=15)
. The
nex
t val
ue (1
6) is
too
larg
e,
so a
0 is
pla
ced
in t
hat
colu
mn.
A 1
is t
hen
plac
ed in
the
8 c
olum
n, a
nd t
he s
ubtr
acti
on is
pe
rfor
med
aga
in (
15-8
=7.)
Rep
eat
the
proc
ess
unti
l the
val
ue o
f th
e su
btra
ctio
n eq
uals
0.
Bin
ary-
to-H
exad
ecim
al C
on
vers
ion
Ano
ther
com
mon
num
beri
ng s
yste
m u
sed
in c
ompu
ting
and
net
wor
king
is h
exad
ecim
al, o
r he
x. H
ex is
a b
ase
16 n
umbe
ring
sys
tem
, whi
ch p
rese
nts
a bi
t of
a p
robl
em, b
ecau
se o
nly
ten
sym
bols
exi
st t
o re
pres
ent
num
bers
. To
acco
unt
for
the
addi
tion
al n
umbe
rs, t
he le
tter
s A
thr
ough
F a
re u
sed
for
the
deci
mal
val
ues
10 t
o 15
. Hex
is a
lso
usef
ul a
s sh
orth
and
for
Un
itB
ytes
Bit
s
Bit
(b)
1/8
byte
1 bi
t
Byt
e (B
)1
byte
8 bi
ts
Kilo
byte
(K
B)
1000
byt
es80
00 b
its
Meg
abyt
e (M
B)
1 m
illio
n by
tes
8 m
illio
n bi
ts
Gig
abyt
e (G
B)
1 bi
llion
byt
es8
billi
on b
its
Bas
e 2
Nu
mb
erin
g S
yste
m
Num
ber
of
Sym
bols
2
Sym
bols
0, 1
Bas
e E
xpon
ent
2726
2524
2322
2120
Plac
e V
alue
128
6432
168
42
1
Exa
mpl
e: C
onve
rt
47 t
o B
inar
y0
01
01
11
1
0791_fm.book Page 583 Wednesday, July 2, 2003 12:13 PM
-
bina
ry. F
our
bina
ry d
igit
s re
pres
ent
16 n
umbe
rs, w
hich
is a
sin
gle
hex
digi
t. T
he f
ollo
win
g ta
ble
show
s th
e co
nver
sion
bet
wee
n bi
nary
, hex
, and
dec
imal
.
Usi
ng h
ex, a
ver
y la
rge
bina
ry s
trin
g of
1s
and
0s c
an b
e re
pres
ente
d by
just
a fe
w h
ex n
um-
bers
. For
exa
mpl
e, 1
0011
0110
0011
111
in b
inar
y eq
uals
9B
1F in
hex
(or
397
11 in
dec
i-m
al).
To
conv
ert
bina
ry t
o he
x, p
ut t
he b
inar
y di
gits
in g
roup
s of
fou
r, st
arti
ng f
rom
the
ri
ghtm
ost
digi
t.
Co
mp
uti
ng
Bas
ics
Su
mm
ary
•C
ompu
ters
use
man
y of
the
sam
e su
bsys
tem
s as
rou
ters
, sw
itch
es, a
nd o
ther
net
wor
k-in
g ge
ar.
•A
bit
is a
sin
gle
stat
e (1
or
0) u
sed
in c
ompu
ter
inst
ruct
ions
. A b
yte
is 8
bit
s an
d is
the
st
anda
rd u
nit
for
com
pute
r da
ta.
•B
inar
y is
a b
ase
2 nu
mbe
ring
sys
tem
use
d ex
tens
ivel
y in
com
pute
r an
d ne
twor
king
sys
-te
ms.
•H
ex is
a 1
6-bi
t nu
mbe
ring
sys
tem
and
is a
n ef
ficie
nt s
hort
hand
met
hod
for
very
larg
e bi
nary
num
bers
.
Net
wo
rkin
g F
un
dam
enta
lsN
etw
orki
ng h
as it
s ow
n ja
rgon
and
com
mon
ter
ms.
The
fol
low
ing
term
s ar
e us
ed t
hrou
gh-
out
the
indu
stry
and
app
ear
man
y ti
mes
in t
his
stud
y gu
ide:
•N
etw
ork
inte
rfac
e ca
rd (
NIC
)—Pr
onou
nced
“ni
ck,”
thi
s ca
rd c
onne
cts
a co
mpu
ter
to
a L
AN
.•
Med
ium
—T
he p
hysi
cal t
rans
port
use
d to
car
ry d
ata.
Mos
t of
the
tim
e th
is c
an b
e ju
st
a ca
ble
(tw
iste
d pa
ir, c
oaxi
al, fi
ber)
, but
it a
lso
incl
udes
air
(fo
r w
irel
ess
tran
smis
sion
).•
Prot
ocol
—A
set
of
com
mun
icat
ion
rule
s us
ed b
y co
mpu
ters
or
netw
ork
devi
ces.
•C
isco
IO
S So
ftw
are—
The
mos
t w
idel
y de
ploy
ed n
etw
ork
syst
em s
oftw
are.
Cis
co I
OS
serv
ices
incl
ude
basi
c co
nnec
tivi
ty, s
ecur
ity,
net
wor
k m
anag
emen
t, a
nd o
ther
adv
ance
d se
rvic
es. E
arly
ver
sion
s of
Cis
co I
OS
coul
d pe
rfor
m o
nly
“sto
re a
nd f
orw
ard”
pac
ket
tran
spor
t. T
he s
oftw
are
is n
ow a
com
plet
e ne
twor
k so
luti
on t
hat
cont
inue
s to
evo
lve.
•C
lient
—A
com
pute
r or
pro
gram
tha
t re
ques
ts in
form
atio
n fr
om a
ser
ver.
•Se
rver
—A
com
pute
r or
pro
gram
tha
t pr
ovid
es s
ervi
ces
or in
form
atio
n to
clie
nts.
Ser
v-er
s ar
e of
ten
dedi
cate
d, m
eani
ng t
hat
they
per
form
no
othe
r ta
sks
beyo
nd s
uppl
ying
in
form
atio
n to
clie
nts.
•N
etw
ork
Ope
rati
ng S
yste
m (N
OS)
—U
sual
ly r
efer
s to
the
oper
atin
g sy
stem
run
ning
on
serv
ers.
Thi
s in
clud
es W
indo
ws
NT,
Win
dow
s 20
00 S
erve
r, N
ovel
l, N
etW
are,
and
U
NIX
.•
Con
nect
ivit
y de
vice
—A
ny d
evic
e th
at c
onne
cts
cabl
e se
gmen
ts, c
onne
cts
two
or m
ore
smal
l net
wor
ks in
to a
larg
er o
ne, o
r di
vide
s a
larg
e ne
twor
k in
to s
mal
l one
s.•
Loc
al-a
rea
netw
ork
(LA
N)—
A n
etw
ork
confi
ned
to a
sm
all g
eogr
aphi
c ar
ea. T
his
can
be a
roo
m, fl
oor,
build
ing,
or
cam
pus.
Dec
imal
-to
-Hex
adec
imal
Eq
uiv
alen
t
Bin
ary
Hex
Dec
imal
0000
00
0001
11
0010
22
0011
33
0100
44
0101
55
0110
66
0111
77
1000
88
1001
99
1010
A10
1011
B11
1100
C12
1101
D13
1110
E14
1111
F15
0791_fm.book Page 584 Wednesday, July 2, 2003 12:13 PM
-
•W
AN
—W
ide-
area
net
wor
k. I
nter
conn
ects
LA
Ns
usin
g le
ased
car
rier
line
s or
sat
ellit
e te
chno
logy
.•
Phys
ical
topo
logy
—A
net
wor
k’s
phys
ical
sha
pe. T
hese
sha
pes
incl
ude
linea
r bu
s, r
ing,
st
ar, a
nd m
esh.
•L
ogic
al t
opol
ogy—
The
pat
h th
at s
igna
ls t
ake
from
one
com
pute
r to
ano
ther
.
Wh
y N
etw
ork
Co
mp
ute
rs?
One
of
a ne
twor
k’s
prim
ary
func
tion
s is
to
incr
ease
pro
duct
ivit
y by
link
ing
com
pute
rs a
nd
com
pute
r ne
twor
ks. C
orpo
rate
net
wor
ks a
re t
ypic
ally
div
ided
into
use
r gr
oups
, whi
ch a
re
usua
lly b
ased
on
grou
ps o
f em
ploy
ees.
Rem
ote-
acce
ss lo
cati
ons
such
as
bran
ches
, hom
e of
fices
, and
mob
ile w
orke
rs u
sual
ly c
onne
ct t
o th
e co
rpor
ate
LA
N u
sing
a W
AN
ser
vice
.
Net
wo
rkin
g A
pp
licat
ion
sA
pplic
atio
ns a
re c
ompu
ter
prog
ram
s th
at r
un o
ver
netw
orks
. An
enti
re s
uite
of
Inte
rnet
ap
plic
atio
ns h
as b
een
deve
lope
d. H
TT
P co
nnec
ts w
eb s
erve
rs w
ith c
lient
bro
wse
rs. P
ost O
ffice
Pr
otoc
ol 3
(PO
P3) i
s us
ed in
e-m
ail a
pplic
atio
ns. F
TP
tran
sfer
s fil
es. N
etw
ork
man
agem
ent
prog
ram
s us
e Si
mpl
e N
etw
ork
Man
agem
ent P
roto
col (
SNM
P). T
hese
app
licat
ions
all
resi
de a
t th
e ap
plic
atio
n la
yer
of a
sta
ndar
d pr
otoc
ol s
uite
use
d th
roug
hout
inte
rnet
wor
king
.
OS
I Mo
del
The
OSI
mod
el is
a s
tan-
dard
ized
fra
mew
ork
for
net-
wor
k fu
ncti
ons
and
sche
mes
. It
bre
aks
othe
rwis
e-co
mpl
ex
netw
ork
inte
ract
ions
into
si
mpl
e el
emen
ts, w
hich
lets
de
velo
pers
mod
ular
ize
desi
gn e
ffor
ts. T
his
met
hod
allo
ws
man
y in
depe
nden
t de
velo
pers
to
wor
k on
sep
a-ra
te n
etw
ork
func
tion
s,
whi
ch c
an b
e ap
plie
d in
a
“plu
g an
d pl
ay”
man
ner.
Prot
ocol
Dat
a U
nits
(PD
Us)
are
use
d to
com
mun
icat
e be
twee
n la
yers
.E
ncap
sula
tion
is t
he m
etho
d of
add
ing
head
ers
and
trai
lers
. As
the
data
mov
es d
own
the
stac
k, t
he r
ecei
ving
dev
ice
stri
ps t
he h
eade
r, w
hich
con
tain
s in
form
atio
n fo
r th
at la
yer
(de-
enca
psul
atio
n).
Dat
a C
om
mu
nic
atio
nFo
r pa
cket
s to
tra
vel f
rom
a s
ourc
e to
a d
esti
nati
on, e
ach
OSI
laye
r of
the
sou
rce
com
pute
r m
ust
com
mun
icat
e w
ith
its
peer
at
the
dest
inat
ion.
Eac
h pa
rt o
f th
e m
essa
ge is
enc
apsu
-la
ted
by t
he la
yer
belo
w it
, and
it is
unw
rapp
ed a
t th
e de
stin
atio
n fo
r us
e by
the
cor
re-
spon
ding
laye
r.
App
licat
ion
Pre
sent
atio
nS
essi
on
Tran
spor
t
Net
wor
k
Dat
a Li
nk
Phy
sica
l
PD
U
Seg
men
t
Pac
ket
Fra
me
Bit
s01
0111
0101
0010
0001
0
Upp
er L
ayer
Dat
a
TC
P H
eade
rU
pper
Lay
er D
ata
IP H
eade
rD
ata
LLC
Hea
der
Dat
a
Dat
aM
AC
Hea
der
FC
S
FC
S
} } } }
OS
I MO
DE
L
App
licat
ion
Use
r in
terf
ace.
Teln
etH
TT
P
Pres
enta
tion
Enc
rypt
ion
and
othe
r pr
oces
sing
.A
SCII
/EB
CD
ICJP
EG
/MP3
Sess
ion
Man
ages
mul
tipl
e ap
plic
atio
ns.
Ope
rati
ng s
yste
ms
Sche
dulin
g
Tra
nspo
rtPr
ovid
es r
elia
ble
or b
est-
effo
rt d
eliv
ery
and
som
e er
ror
corr
ecti
on.
TC
PU
DP
SPX
Net
wor
kPr
ovid
es lo
gica
l add
ress
ing
used
by
rout
ers
and
the
netw
ork
hier
arch
y.IP IP
X
Dat
a lin
kC
reat
es f
ram
es f
rom
bit
s of
dat
a.U
ses
MA
C a
ddre
sses
to
acce
ss
endp
oint
s.Pr
ovid
es e
rror
det
ecti
on b
ut n
o co
rrec
tion
.
802.
380
2.2
HD
LC
Fram
e R
elay
Phys
ical
Spec
ifies
vol
tage
, wir
e sp
eed,
and
cab
le
pin-
outs
.E
IA/T
IAV
.35
0791_fm.book Page 585 Wednesday, July 2, 2003 12:13 PM
-
Th
e T
CP
/IP
Mo
del
The
TC
P/IP
sui
te o
f pr
otoc
ols
is u
sed
to
com
mun
icat
e ac
ross
any
set
of
inte
rcon
-ne
cted
net
wor
ks. T
hese
pro
toco
ls, i
nitia
lly
deve
lope
d by
Def
ense
Adv
ance
d R
esea
rch
Proj
ects
Age
ncy
(DA
RPA
), a
re w
ell-
suit
ed
for
com
mun
icat
ion
acro
ss b
oth
LA
Ns
and
WA
Ns.
The
pro
toco
l sui
te in
clud
es L
ayer
3
and
4 sp
ecifi
catio
ns, a
s w
ell a
s sp
ecifi
catio
ns
for
high
er-l
ayer
app
licat
ions
suc
h as
e-m
ail
and
file
tran
sfer
.T
he T
CP/
IP p
roto
col s
tack
clo
sely
fol
low
s th
e O
SI r
efer
ence
mod
el. A
ll st
anda
rd L
ayer
1 a
nd 2
pro
toco
ls a
re s
uppo
rted
(ca
lled
the
netw
ork
inte
rfac
e la
yer
in T
CP/
IP).
TC
P/I
P D
atag
ram
sT
CP/
IP in
form
atio
n is
sen
t vi
a da
tagr
ams.
One
mes
sage
may
be
brok
en in
to a
ser
ies
of d
at-
agra
ms
that
are
rea
ssem
bled
at t
he d
esti
nati
on. T
hree
laye
rs a
re a
ssoc
iate
d w
ith
the
TC
P/IP
pr
otoc
ol s
tack
:•
App
licat
ion
laye
r—Sp
ecifi
cati
ons
exis
t fo
r e-
mai
l, fil
e tr
ansf
er, r
emot
e lo
gin,
and
oth
er
appl
icat
ions
. Net
wor
k m
anag
emen
t is
als
o su
ppor
ted.
•T
rans
port
laye
r—Tr
ansp
ort s
ervi
ces
allo
w m
ulti-
ple
uppe
r-la
yer
appl
icat
ions
to u
se th
e sa
me
data
st
ream
. TC
P an
d U
DP
prot
ocol
s ex
ist
at t
his
laye
r, pr
ovid
ing
the
follo
win
g fu
ncti
ons:
—Fl
ow c
ontr
ol (
thro
ugh
win
dow
ing)
—R
elia
bilit
y (t
hrou
gh s
eque
nce
num
bers
and
ac
know
ledg
men
ts)
•In
tern
et la
yer—
Seve
ral p
roto
cols
ope
rate
at
the
TC
P/IP
Int
erne
t la
yer:
—IP
pro
vide
s co
nnec
tion
less
, bes
t-ef
fort
rou
ting
of
data
gram
s.
—IC
MP
prov
ides
con
trol
and
mes
sagi
ng c
apab
iliti
es.
—A
RP
dete
rmin
es t
he d
ata
link
laye
r ad
dres
s fo
r kn
own
IP a
ddre
sses
.
—R
AR
P de
term
ines
net
wor
k ad
dres
ses
whe
n da
ta li
nk la
yer
addr
esse
s ar
e kn
own.
Oth
er In
tern
et L
ayer
Pro
toco
lsIC
MP,
AR
P, a
nd R
AR
P ar
e th
ree
prot
ocol
s us
ed b
y th
e In
tern
et la
yer.
Inte
rnet
Con
trol
Mes
sage
Pro
toco
l (I
CM
P) s
ends
err
or a
nd c
ontr
ol m
essa
ges,
suc
h as
de
stin
atio
n un
reac
habl
e, t
ime
exce
eded
, sub
net
mas
k re
ques
t, e
cho,
and
oth
ers.
Add
ress
Res
olut
ion
Prot
ocol
(A
RP)
is u
sed
to m
ap a
kn
own
IP a
ddre
ss t
o a
MA
C s
ubla
yer
addr
ess.
An
AR
P ca
che
tabl
e is
che
cked
whe
n lo
okin
g fo
r a
dest
i-na
tion
add
ress
. If
the
addr
ess
is n
ot in
the
tab
le, A
RP
send
s a
broa
dcas
t lo
okin
g fo
r th
e de
stin
atio
n st
atio
n.
Rev
erse
AR
PR
ever
se A
ddre
ss R
esol
utio
n Pr
otoc
ol (
RA
RP)
is u
sed
to m
ap a
kno
wn
MA
C a
ddre
ss t
o an
IP
addr
ess.
Dyn
amic
Hos
t C
onfig
urat
ion
Prot
ocol
(D
HC
P) is
a m
oder
n im
plem
enta
tion
of
RA
RP.
Net
wo
rkin
g F
un
dam
enta
ls S
um
mar
y•
The
OSI
mod
el p
rovi
des
a st
anda
rdiz
ed m
etho
d of
cre
atin
g an
d im
plem
entin
g ne
twor
k st
anda
rds
and
sche
mes
.•
The
OSI
mod
el a
llow
s “p
lug
and
play
” ap
plic
atio
ns, s
impl
ified
bui
ldin
g bl
ocks
, and
m
odul
ariz
ed d
evel
opm
ent.
•T
he O
SI m
odel
has
sev
en la
yers
. Mne
mon
ics
are
usef
ul f
or r
emem
beri
ng t
he la
yers
an
d th
eir
func
tion
s (P
DN
TSP
A).
•E
ncap
sula
tion
is t
he p
roce
ss o
f ad
ding
laye
r-sp
ecifi
c in
stru
ctio
ns a
nd in
form
atio
n (f
or t
he r
ecei
ving
dev
ice)
as
head
ers
and
trai
lers
.•
De-
enca
psul
atio
n is
the
rev
erse
of
enca
psul
atio
n.•
The
TC
P/IP
mod
el h
as fo
ur la
yers
: app
licat
ion,
tran
spor
t, In
tern
et, a
nd n
etw
ork
acce
ss.
Net
wo
rk D
evic
esL
ayer
1 d
evic
es o
pera
te a
t th
e ph
ysic
al
laye
r an
d ar
e on
ly in
volv
ed in
tran
smitt
ing
sign
als
(mov
ing
bits
). T
he t
wo
mos
t co
mm
on L
ayer
1 d
evic
es a
re r
epea
ters
an
d hu
bs. R
epea
ters
are
nec
essa
ry
beca
use
a si
gnal
’s qu
alit
y de
grad
es o
ver
dist
ance
, eve
ntua
lly b
ecom
ing
unre
ad-
7 6 5 4 3 2 1
Ap
plic
atio
n
Pre
sen
tati
on
Ses
sio
n
Tran
spo
rt
Net
wo
rk
Dat
a L
ink
Phy
sica
l
5 4 3 2 1
Ap
plic
atio
n
Tran
spo
rt
Inte
rnet
Dat
a L
ink
Phy
sica
l
������
App
licat
ion
Tran
spor
t
ICM
P
Inte
rnet
Dat
a Li
nk
Phy
sica
l
Des
tinat
ion
Unr
each
able
Ech
o (P
ing)
Oth
er
1
ICM
P
0791_fm.book Page 586 Wednesday, July 2, 2003 12:13 PM
-
able
. Rep
eate
rs r
egen
erat
e an
d re
tim
e (o
r cl
ean
up)
the
sign
al, a
llow
ing
it t
o tr
avel
a lo
nger
di
stan
ce o
ver
a gi
ven
med
ium
. Rep
eate
rs c
an b
e si
ngle
-por
t (o
ne in
, one
out
) or
mul
tipo
rt.
Hub
s ar
e si
mila
r to
rep
eate
rs a
nd a
re o
ften
cal
led
mul
ti-
port
rep
eate
rs (
usua
lly h
avin
g fr
om f
our
to 2
0 po
rts.
) H
ubs
prov
ide
no fi
lter
ing
or in
telli
genc
e; t
hey
sim
ply
clea
n up
sig
nals
. Hub
s al
so in
crea
se n
etw
ork
relia
bilit
y by
isol
atin
g en
dpoi
nts.
Usi
ng a
hub
, if a
sin
gle
cabl
e fa
ils,
the
netw
ork
cont
inue
s to
ope
rate
. A g
roup
of
devi
ces
conn
ecte
d to
the
sam
e ph
ysic
al m
ediu
m is
kno
wn
as a
co
llisi
on d
omai
n. I
f tw
o de
vice
s tr
ansm
it a
sig
nal a
t th
e sa
me
tim
e, a
col
lisio
n re
sult
s. E
ther
net
devi
ces
use
a m
etho
d ca
lled
carr
ier
sens
e m
ulti
ple
acce
ss c
ollis
ion
dete
ct (
CSM
A/C
D)
whe
n se
ndin
g bi
ts. W
hen
a co
llisi
on
occu
rs, b
oth
stat
ions
res
end
the
sign
al a
fter
a r
ando
m
peri
od. C
ollis
ions
incr
ease
wit
h th
e nu
mbe
r of
sta
tion
s an
d re
duce
usa
ble
band
wid
th.
Lay
er 2
dev
ices
ope
rate
at
the
data
link
laye
r an
d, in
mos
t ca
ses,
isol
ate
endp
oint
s, a
void
-in
g da
ta c
ollis
ions
(di
scus
sed
late
r). D
evic
es s
uch
as b
ridg
es a
nd s
wit
ches
use
MA
C
addr
esse
s to
sw
itch
dat
a fr
ames
.N
ICs
are
cons
ider
ed L
ayer
2 d
evic
es b
ecau
se t
hey
prov
ide
MA
C a
ddre
sses
use
d by
oth
er
Lay
er 2
dev
ices
.B
ridg
es c
onne
ct L
AN
seg
men
ts a
nd is
o-la
te c
ollis
ion
dom
ains
, whi
ch in
crea
ses
band
wid
th. B
ridg
es k
eep
loca
l tra
ffic
from
goi
ng to
oth
er L
AN
seg
men
ts b
ut
can
filte
r tr
affic
inte
nded
for
othe
r L
AN
se
gmen
ts u
sing
the
MA
C a
ddre
ss o
f the
de
stin
atio
n en
dpoi
nt. B
ridg
es k
eep
trac
k of
des
tinat
ions
in M
AC
add
ress
tabl
es.
Swit
ches
(or
LA
N s
wit
ches
) ar
e si
mila
r to
bri
dges
and
hav
e al
l the
sam
e fu
ncti
onal
ity
but
are
typi
cally
muc
h fa
ster
bec
ause
the
swit
chin
g fu
ncti
ons
are
perf
orm
ed in
har
dwar
e ra
ther
th
an s
oftw
are
(whi
ch is
wha
t br
idge
s us
e). S
wit
ches
als
o su
ppor
t vi
rtua
l LA
Ns
(VL
AN
s,
disc
usse
d la
ter)
.
Lay
er 3
dev
ices
ope
rate
at
the
netw
ork
laye
r of
the
OSI
mod
el, w
hich
use
s a
diff
eren
t ad
dres
sing
sch
eme
than
Lay
er 2
dev
ices
. IP
addr
esse
s (d
iscu
ssed
late
r) a
re o
ne t
ype
of
Lay
er 3
dev
ice.
The
tw
o m
ost
com
mon
Lay
er 3
dev
ices
are
rou
ters
and
mul
tila
yer
swit
ches
.R
oute
rs p
ass
data
pac
kets
bet
wee
n ne
t-w
orks
bas
ed o
n th
eir
IP (
or o
ther
Lay
er
3) a
ddre
ss. R
oute
rs c
an m
ake
inte
llige
nt
deci
sion
s ab
out
the
best
pat
h a
pack
et
can
take
acr
oss
the
netw
ork.
Rou
ters
al
so c
an c
onne
ct d
iffer
ent t
ypes
of L
ayer
2
netw
orks
. Rou
ters
reg
ulat
e tr
affic
and
m
ake
up t
he b
ackb
one
of m
ost
IP n
et-
wor
ks.
Mul
tilay
er sw
itche
s are
the
sam
e as
regu
lar
Lay
er 2
sw
itch
es b
ut c
an p
roce
ss a
nd
mak
e sw
itchi
ng d
ecis
ions
bas
ed o
n L
ayer
3
addr
esse
s. T
his
adva
nce
was
ena
bled
be
caus
e of
hig
h-sp
eed
soft
war
e em
bedd
ed
in h
ardw
are
ASI
Cs.
Thi
s ha
s re
duce
d th
e bo
ttle
neck
tha
t us
ed t
o oc
cur
wit
h so
ftw
are-
base
d L
ayer
3 d
evic
es. U
sing
Lay
er 3
add
ress
es a
llow
s m
ulti
laye
r sw
itch
es t
o im
plem
ent
qual
ity
and
secu
rity
pol
icie
s.V
oice
, DSL
, and
opt
ical
dev
ices
: As
voic
e an
d da
ta n
etw
orks
con
verg
e, s
ever
al n
ew d
evic
es
have
bee
n de
velo
ped.
Voi
ce g
atew
ays
hand
le v
oice
and
dat
a pa
cket
s m
ovin
g ov
er a
sin
gle
netw
ork.
Dig
ital
Sub
scri
ber
Lin
e A
cces
s M
ulti
plex
ers
(DSL
AM
s) s
erve
as
the
hand
off p
oint
be
twee
n a
subs
crib
er n
etw
ork
and
a ca
rrie
r ne
twor
k. O
ptic
al p
latf
orm
s ar
e us
ed f
or h
igh-
spee
d, lo
ng-d
ista
nce
tran
spor
ts.
Fire
wal
ls a
nd A
uthe
ntic
atio
n, A
utho
riza
tion
, and
Acc
ount
ing
(AA
A)
serv
ers
wor
k at
the
hi
gher
laye
rs o
f th
e O
SI m
odel
to
prov
ide
secu
rity
for
net
wor
ks. A
fire
wal
l can
be
eith
er a
ph
ysic
al d
evic
e or
a s
oftw
are
prog
ram
. Fir
ewal
ls p
rote
ct s
yste
ms
by a
ctin
g as
a t
raffi
c co
p fo
r da
ta e
nter
ing
a pr
ivat
e ne
twor
k. T
heir
job
is t
o al
low
onl
y va
lid t
raffi
c (a
s de
fined
by
the
netw
ork
adm
in)
and
bloc
k al
l oth
er t
ypes
of
traf
fic. A
AA
ser
vers
kee
p un
auth
oriz
ed
user
s fr
om a
cces
sing
sen
siti
ve d
ata
and
mon
itor
aut
hori
zed
usag
e to
pro
tect
aga
inst
thef
t or
mis
use.
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0791_fm.book Page 587 Wednesday, July 2, 2003 12:13 PM
-
Net
wo
rk D
evic
es S
um
mar
y•
Net
wor
king
dev
ices
are
use
d to
con
nect
net
wor
ks. H
ubs,
sw
itch
es, a
nd r
oute
rs in
ter-
conn
ect
devi
ces
wit
hin
LA
Ns,
MA
Ns,
and
WA
Ns.
Net
wor
king
dev
ices
fun
ctio
n at
dif
-fe
rent
laye
rs o
f th
e O
SI m
odel
.•
Hub
s op
erat
e at
Lay
er 1
and
mak
e no
dec
isio
ns. A
ll de
vice
s co
nnec
ted
to a
hub
are
on
a sh
ared
med
ium
and
are
par
t of
a s
ingl
e co
llisi
on d
omai
n.•
LA
N s
wit
ches
wor
k at
Lay
er 2
and
dec
ide
whe
ther
to
forw
ard
and
flood
dat
a fr
ames
ba
sed
on M
AC
add
ress
es.
•R
oute
rs c
an m
ake
deci
sion
s re
gard
ing
the
best
pat
h fo
r de
liver
y of
dat
a on
the
netw
ork.
•Fi
rew
alls
and
AA
A s
erve
rs p
rovi
de s
ecur
ity
to t
he n
etw
ork.
Net
wo
rk T
op
olo
gie
sA
top
olog
y re
fers
to
the
way
in w
hich
net
wor
k de
vice
s ar
e co
n-ne
cted
. A p
hysi
cal t
opol
ogy
refe
rs t
o th
e ph
ysic
al la
yout
of
the
endp
oint
s an
d th
e co
nnec
ting
cab
les.
A lo
gica
l top
olog
y re
fers
to
how
sig
nals
tra
vel f
rom
end
poin
t to
end
poin
t. T
he p
hysi
cal
and
logi
cal t
opol
ogie
s ca
n be
the
sam
e or
dif
fere
nt. A
n ex
ampl
e of
this
is a
net
wor
k in
whi
ch e
ach
endp
oint
is c
onne
cted
to e
very
oth
er e
ndpo
int (
a m
eshe
d ne
twor
k) b
ut t
he s
igna
l can
flow
in o
nly
sequ
enti
al o
rder
(a
ring
net
wor
k). T
he f
ollo
win
g se
ctio
ns d
iscu
ss e
ach
of t
he t
opol
ogie
s.A
bus
or
linea
r bu
s co
nnec
ts a
ll de
vice
s w
ith
a si
ngle
cab
le. T
he e
nds
of t
he w
ire
mus
t be
co
nnec
ted
to a
dev
ice
or t
erm
inat
or, o
r si
gnal
s w
ill b
ounc
e ba
ck a
nd c
ause
err
ors.
Onl
y a
sing
le p
acke
t can
be
tran
smit
ted
at a
tim
e on
a b
us, o
r th
e pa
cket
s w
ill c
ollid
e an
d bo
th w
ill
be d
estr
oyed
(an
d m
ust
be r
esen
t).
In a
rin
g to
polo
gy, a
fra
me
trav
els
in a
logi
cal o
rder
aro
und
the
ring
, go
ing
from
one
end
sta
tion
to
the
next
. If
an e
nd s
tati
on w
ants
to
send
da
ta, i
t is
add
ed t
o th
e fr
ame.
The
fra
me
cont
inue
s ar
ound
the
rin
g, a
nd
the
data
is r
emov
ed a
t th
e in
tend
ed d
esti
nati
on. T
he f
ram
e, h
owev
er,
cont
inue
s. I
n a
sing
le r
ing,
dat
a tr
avel
s in
a s
ingl
e di
rect
ion.
In
a du
al
ring
, eac
h ri
ng s
ends
dat
a in
a d
iffe
rent
dir
ecti
on. T
wo
ring
s cr
eate
re
dund
ancy
, or
faul
t to
lera
nce,
whi
ch m
eans
tha
t if
one
rin
g fa
ils, t
he s
yste
m c
an s
till
oper
-at
e. I
f pa
rts
of b
oth
ring
s fa
il, a
“w
rap”
(a
conn
ecti
on b
etw
een
the
two
ring
s) c
an h
eal t
he
faul
t.
Star
top
olog
ies
are
the
mos
t co
mm
only
use
d ph
ysic
al t
opol
ogy
in
Eth
erne
t L
AN
s. S
tars
hav
e a
cent
ral c
onne
ctio
n (h
ub, s
wit
ch, o
r ro
uter
) w
here
all
end
devi
ces
mee
t. S
tars
cos
t m
ore
than
oth
er t
opol
o-gi
es b
ut a
re m
ore
faul
t-to
lera
nt b
ecau
se a
cab
le f
ailu
re u
sual
ly a
ffec
ts
only
one
end
dev
ice,
or
host
. The
dis
adva
ntag
e of
a s
tar
is t
hat
if t
he
cent
ral d
evic
e fa
ils, t
he w
hole
sys
tem
fai
ls.
In a
n ex
tend
ed s
tar,
the
cent
ral n
etw
orki
ng d
evic
e co
nnec
ts t
o ot
her
netw
orki
ng d
evic
es, w
hich
the
n co
nnec
t to
end
sta
tion
s.
In a
ful
l-m
esh
topo
logy
, all
devi
ces
are
conn
ecte
d to
all
othe
r de
vice
s-T
here
is g
reat
red
unda
ncy
on f
ull-
mes
h ne
twor
ks, b
ut f
or n
etw
orks
w
ith
mor
e th
an a
few
dev
ices
, it
beco
mes
ove
rly
expe
nsiv
e an
d co
m-
plic
ated
. Par
tial
-mes
h to
polo
gies
, whi
ch h
ave
at le
ast
one
devi
ce w
ith
mul
tipl
e co
nnec
tion
s, p
rovi
de g
ood
redu
ndan
cy w
itho
ut t
he e
xpen
se
of f
ull m
eshe
s.
Net
wo
rk T
op
olo
gie
s S
um
mar
y•
A p
hysi
cal t
opol
ogy
desc
ribe
s th
e pl
an f
or w
irin
g th
e ph
ysic
al
devi
ces.
A lo
gica
l top
olog
y de
scri
bes
how
info
rmat
ion
flow
s th
roug
h a
netw
ork.
•In
a p
hysi
cal b
us t
opol
ogy,
a s
ingl
e ca
ble
conn
ects
all
devi
ces.
•T
he m
ost
com
mon
ly u
sed
arch
itec
ture
in E
ther
net
LA
Ns
is t
he p
hysi
cal s
tar
topo
logy
, in
whi
ch e
ach
host
is c
onne
cted
to
a ce
ntra
l dev
ice.
•In
a r
ing
topo
logy
, all
the
host
s ar
e co
nnec
ted
in t
he f
orm
of
a ri
ng o
r ci
rcle
.•
In a
ful
l-m
esh
topo
logy
, all
devi
ces
are
conn
ecte
d to
eac
h ot
her.
LAN
sE
ther
net
is o
ne o
f th
e m
ost
wid
ely
used
L
AN
sta
ndar
ds. E
ther
net o
pera
tes
at L
ayer
2,
the
data
link
laye
r. T
his
laye
r ha
s th
e fo
llow
ing
func
tion
s:•
It p
erfo
rms
phys
ical
add
ress
ing.
•It
pro
vide
s su
ppor
t fo
r co
nnec
tion
-or
ient
ed a
nd c
onne
ctio
nles
s se
rvic
es.
•It
pro
vide
s fr
ame
sequ
enci
ng a
nd fl
ow
cont
rol.
EIA
/TIA
-232
v.35
802.
2
802.
3
HDLC
Frame Relay
Ethernet
PhysicalData Link
0791_fm.book Page 588 Wednesday, July 2, 2003 12:13 PM
-
Two
subl
ayer
s pe
rfor
m d
ata
link
func
tion
s: t
he M
AC
laye
r an
d th
e L
LC
laye
r.M
edia
Acc
ess
Con
trol
(M
AC
) su
blay
er (
802.
3) is
res
pons
ible
for
how
dat
a is
sen
t ov
er t
he
wir
e. T
he M
AC
add
ress
is a
48-
bit
addr
ess
expr
esse
d as
12
hex
digi
ts.
MA
C d
efine
s th
e fo
llow
ing:
•Ph
ysic
al a
ddre
ssin
g•
Net
wor
k to
polo
gy•
Lin
e di
scip
line
•E
rror
not
ifica
tion
•O
rder
ly d
eliv
ery
of f
ram
es•
Opt
iona
l flow
con
trol
Log
ical
Lin
k C
ontr
ol (
LL
C)
subl
ayer
(80
2.2)
is r
espo
nsib
le
for
iden
tify
ing
and
enca
psul
at-
ing
diff
eren
t pr
otoc
ol t
ypes
. T
here
are
tw
o ty
pes
of L
LC
fr
ames
: Ser
vice
Acc
ess
Poin
t (S
AP)
and
Sub
netw
ork
Acc
ess
Prot
ocol
(SN
AP)
. SN
AP
is u
sed
to s
uppo
rt n
on-8
02 p
roto
cols
.
The
term
Eth
erne
t enc
ompa
sses
se
vera
l LA
N im
plem
enta
tion
s.
Phys
ical
laye
r im
plem
enta
tion
s va
ry, a
nd a
ll su
ppor
t va
riou
s ca
blin
g st
ruct
ures
. The
re a
re f
our
mai
n ca
tego
ries
:•
Eth
erne
t (D
IX)
and
IEE
E
802.
3—O
pera
te a
t 10
Mbp
s ov
er c
oaxi
al c
able
, UT
P, o
r fib
er. T
he s
tand
ards
are
ref
erre
d to
as
10B
ASE
2, 1
0BA
SE5,
and
10B
ASE
-T.
•Fa
st E
ther
net,
or
100
Mbp
s E
ther
net—
Ope
rate
s ov
er U
TP
or fi
ber.
•G
igab
it E
ther
net—
An
802.
3 ex
tens
ion
oper
ates
ove
r fib
er a
nd c
oppe
r at
100
0 M
bps,
or
1 g
igab
it p
er s
econ
d (G
bps)
.•
10-G
igab
it Et
hern
et—
Thi
s is
now
bei
ng s
tand
ardi
zed
and
will
off
er s
peed
s of
10
billi
on
bits
per
sec
ond
over
fibe
r.T
his
tabl
e co
mpa
res
cabl
e an
d co
nnec
ter
spec
ifica
tion
s. F
ast
Eth
erne
t re
quir
es u
nshi
elde
d tw
iste
d-pa
ir (
UT
P) C
ateg
ory
5 (o
r hi
gher
) ca
blin
g.
A G
igab
it I
nter
face
Con
vert
er (
GB
IC)
conv
erts
ele
ctri
cal s
igna
ls t
o op
tica
l sig
nals
for
tra
ns-
mis
sion
ove
r fib
er c
able
s (a
s w
ell a
s th
e re
vers
e pr
oces
s). G
BIC
s el
imin
ate
the
need
to
repl
ace
enti
re b
oard
s w
hen
opti
cal t
rans
mis
sion
is d
esir
ed.
Ho
w E
ther
net
Wo
rks
All
stat
ions
on
an E
ther
net
segm
ent
are
conn
ecte
d to
the
sam
e w
ire.
The
refo
re, a
ll de
vice
s re
ceiv
e al
l sig
nals
. Whe
n de
vice
s se
nd s
igna
ls a
t the
sam
e ti
me,
a c
ollis
ion
occu
rs. A
sch
eme
is n
eede
d to
det
ect
and
com
pens
ate
for
colli
sion
s.•
Col
lisio
n do
mai
n—A
gro
up o
f dev
ices
con
nect
ed to
the
sam
e ph
ysic
al m
ediu
m s
uch
that
if
two
devi
ces
acce
ss th
e m
ediu
m a
t the
sam
e tim
e, a
col
lisio
n re
sults
. Eth
erne
t dev
ices
use
a
met
hod
calle
d C
SMA
/CD
whe
n se
ndin
g bi
ts. W
hen
a co
llisi
on o
ccur
s, b
oth
stat
ions
re
send
the
sign
al a
fter
a r
ando
m p
erio
d. C
ollis
ions
incr
ease
with
the
num
ber
of s
tatio
ns.
•B
road
cast
dom
ain—
A g
roup
of
devi
ces
on t
he n
etw
ork
that
rec
eive
one
ano
ther
s’
broa
dcas
t m
essa
ges.
MA
C L
ayer
- 8
02.3
#Byt
es8
66
2V
aria
ble
4
Eth
erne
t II
Use
s "T
ype"
Her
e an
dD
oes
Not
Use
802.
2.00
00.0
Cxx
.xxx
x
IEE
E A
ssig
ned
Ven
dor
Ass
igne
d
MA
C A
dd
ress
Pre
amb
leD
est
Ad
dS
ou
rce
Ad
dL
eng
thD
ata
FC
S
802.
2 (S
NA
P)
1 111
1 or
2
1 or
2
32
Var
iabl
e
Var
iabl
e
802.
2 (S
AP
)O
r
Des
t S
AP
AA
So
urc
e S
AP
AA
Ctr
l03
OU
IID
Typ
eD
ata
Dat
aD
est
SA
PS
ou
rce
SA
PC
trl
MA
C L
ayer
- 8
02.3
Pre
amb
leD
est
add
So
urc
e ad
dL
eng
thD
ata
FC
S
Dat
a L
ink
(MA
C la
yer)
Phy
sica
l
Ethernet
10Base2
802.
3
10Base5
10BaseT
10BaseF
100BaseTX
100BaseFX
100BaseT4
DIX
Sta
ndar
d80
2.3
Spe
cific
atio
ns fo
r10
Mb
Eth
erne
t
802.
3uS
peci
ficat
ions
for
100
Mb
(Fas
t)E
ther
net
10B
AS
E5
10B
AS
ET
100B
AS
ET
X10
0BA
SE
FX
Med
ia
50-o
hm
coax
(t
hick
EIA
/TIA
Cat
3,
4, 5
UT
P 2
pair
EIA
/TIA
Cat
5
UT
P2
pair
62.5
/125
mic
ron
mul
tim
ode
fiber
Max
imu
m
Seg
men
t Le
ng
th
500
met
ers
100
met
ers
100
met
ers
400
met
ers
Top
olo
gy
Bus
Star
Star
Po
int-
to-P
oint
Co
nn
ecto
r
AU
IIS
O 8
877
(RJ-
45)
ISO
887
7 (R
J-45
)D
uple
x m
edia
-in
terf
ace
conn
ecto
r (M
IC)
0791_fm.book Page 589 Wednesday, July 2, 2003 12:13 PM
-
LAN
Su
mm
ary
•L
AN
sta
ndar
ds s
peci
fy c
ablin
g an
d si
gnal
ing
at th
e ph
ysic
al a
nd d
ata
link
laye
rs o
f the
O
SI m
odel
.•
Seve
ral t
ypes
of
Eth
erne
t ex
ist:
Eth
erne
t, F
ast
Eth
erne
t, G
igab
it E
ther
net,
and
10-
Gig
abit
Eth
erne
t. E
ach
type
has
a d
iffe
rent
tra
nsfe
r ra
te.
•C
isco
GB
IC c
ards
are
hot
-sw
appa
ble
and
plug
into
an
Eth
erne
t po
rt.
•E
ther
net
uses
CSM
A/C
D.
WA
Ns
WA
Ns
inte
rcon
nect
LA
Ns
and
oper
ate
at L
ayer
s 1
thro
ugh
3 of
the
OSI
mod
el. W
AN
s op
erat
e ov
er la
rge
geog
raph
ic a
reas
, use
car
rier
ser
vice
s, c
an p
rovi
de f
ull-
or
part
-tim
e co
nnec
tivi
ty, a
nd u
se m
any
diff
eren
t ty
pes
of s
eria
l con
nect
ions
to
conn
ect
netw
orks
.G
loba
l Int
erne
t: A
ltho
ugh
any
netw
ork
of n
etw
orks
is c
onsi
dere
d an
inte
rnet
, the
Int
erne
t is
an
inte
rcon
nect
ion
of th
ousa
nds
of n
etw
orks
all
over
the
wor
ld, a
rran
ged
in a
hie
rarc
hy. T
he
Inte
rnet
bac
kbon
e ca
rrie
s hi
gh-s
peed
dat
a ov
er c
arri
er n
etw
orks
. The
bac
kbon
e co
nnec
ts
man
y In
tern
et s
ervi
ce p
rovi
der
(ISP
) ne
twor
ks, w
hich
in t
urn
conn
ect
to m
illio
ns o
f us
ers.
WA
N c
onne
ctio
ns c
an b
e on
e of
the
fol
low
ing
type
s:•
Ded
icat
ed c
onne
ctio
ns (
also
cal
led
poin
t-to
-poi
nt o
r le
ased
-lin
e co
nnec
tion
s) p
rovi
de
a pr
e-es
tabl
ishe
d pa
th o
ver
a ca
rrie
r ne
twor
k be
twee
n tw
o cu
stom
er n
etw
orks
.•
Cir
cuit
-sw
itch
ed c
onne
ctio
ns u
se a
ded
icat
ed p
hysi
cal p
ath
thro
ugh
a ca
rrie
r ne
twor
k th
at is
est
ablis
hed
and
mai
ntai
ned
only
for
the
leng
th o
f co
mm
unic
atio
n.•
Pack
et-s
wit
ched
con
nect
ions
use
sin
gle
poin
t-to
-poi
nt c
onne
ctio
ns t
o ex
chan
ge d
ata
over
a c
arri
er n
etw
ork.
Fra
me
Rel
ay is
a p
acke
t-sw
itch
ed t
echn
olog
y.•
Cel
l sw
itch
ing
is s
imila
r to
pac
ket
swit
chin
g bu
t us
es fi
xed
cell
size
s to
sen
d da
ta
(pac
ket
swit
chin
g us
es v
aria
ble
size
s).
WA
Ns
use
mul
tipl
e ty
pes
of d
evic
es, i
nclu
ding
the
fol
low
ing:
•R
oute
rs, w
hich
pro
vide
man
y se
rvic
es o
ver
mul
tipl
e pr
otoc
ols
•W
AN
sw
itch
es, w
hich
logi
cally
con
nect
oth
er W
AN
dev
ices
suc
h as
rou
ters
A W
AN
ser
vice
pro
vide
r as
sign
s yo
ur o
rgan
izat
ion
the
para
met
ers
requ
ired
for
mak
ing
the
WA
N li
nk c
onne
ctio
n.C
usto
mer
Pre
mis
es E
quip
men
t (C
PE)
is lo
cate
d on
the
sub
scri
ber’s
pre
mis
es a
nd in
clud
es
both
equ
ipm
ent
owne
d by
the
sub
scri
ber
and
devi
ces
leas
ed b
y th
e se
rvic
e pr
ovid
er.
Dem
arca
tion
(de
mar
c) m
arks
the
poi
nt w
here
CPE
end
s an
d th
e lo
cal l
oop
begi
ns. U
sual
ly
it is
loca
ted
in t
he t
elec
omm
unic
atio
ns c
lose
t.L
ocal
loop
, or
“las
t-m
ile,”
is th
e ca
blin
g fr
om
the
dem
arc
into
the
WA
N
serv
ice
prov
ider
’s ce
ntra
l of
fice.
The
cen
tral
offi
ce (
CO
) is
a
swit
chin
g fa
cilit
y th
at
prov
ides
a p
oint
of
pres
-en
ce f
or W
AN
ser
vice
. T
he c
entr
al o
ffice
is t
he
entr
y po
int
to t
he W
AN
cl
oud,
the
exit
poi
nt fr
om
the
WA
N f
or c
alle
d de
vice
s, a
nd a
sw
itch
ing
poin
t fo
r ca
lls.
The
tol
l net
wor
k is
a c
olle
ctio
n of
tru
nks
insi
de t
he W
AN
clo
ud.
WA
N S
ervi
ce P
rovi
der
s an
d S
ign
alin
g S
tan
dar
ds
WA
N li
nks
can
be o
rder
ed f
rom
ser
vice
pro
vide
rs a
t va
riou
s sp
eeds
usi
ng v
ario
us s
igna
ling
stan
dard
s. T
he f
ollo
win
g ta
ble
show
s th
e si
gnal
ing
type
s an
d sp
eeds
ava
ilabl
e in
the
U.S
.
Lin
e Ty
pe
Sig
nal
Sta
nd
ard
Bit
Rat
e C
apac
ity
56D
S056
kbp
s
64D
S064
kbp
s
T1
DS1
1.54
4 M
bps
E1
ZM
2.04
8 M
bps
E3
M3
34.0
64 M
bps
J1Y
11.
544
Mbp
s
T3
DS3
44.7
36 M
bps
OC
-1SO
NE
T51
.84
Mbp
s
Po
int-
to-P
oin
t o
r C
ircu
it-S
wit
ched
Co
nn
ecti
on
WA
N S
ervi
ce P
rovi
der
Toll
Net
wor
k
CO
Sw
itch
Loca
l Loo
p Dem
arca
tion
Cus
tom
er P
rem
ises
Equ
ipm
ent
(CP
E)
Trun
ks a
nd S
witc
hes
S
S
S
S
S
S
S
0791_fm.book Page 590 Wednesday, July 2, 2003 12:13 PM
-
WA
N P
hys
ical
Lay
er P
roto
cols
Phys
ical
laye
r pr
otoc
ols
spec
ify
the
elec
tric
al, m
echa
nica
l, op
erat
iona
l, an
d fu
ncti
onal
co
nnec
tion
for
WA
N s
ervi
ces.
The
five
ser
ial s
tand
ards
sup
port
ed b
y C
isco
dev
ices
are
EIA
/T
IA-2
32, E
IA/T
IA-4
49, V
.35,
X.2
1, a
nd E
IA/T
IA-5
30.
WA
N D
ata
Lin
k La
yer
Pro
toco
lsD
ata
link
prot
ocol
s op
erat
e ov
er p
oint
-to-
poin
t, m
ulti
poin
t, a
nd m
ulti
acce
ss s
wit
ched
se
rvic
es. T
he f
ollo
win
g ar
e co
mm
on e
ncap
sula
tion
pro
toco
ls:
•H
igh-
Lev
el D
ata
Lin
k C
ontr
ol (
HD
LC
)—T
he
defa
ult
enca
psul
atio
n ty
pe o
n po
int-
to-p
oint
, de
dica
ted
links
, and
cir
-cu
it-s
wit
ched
con
nec-
tion
s. H
DL
C s
houl
d be
us
ed w
hen
com
mun
icat
-in
g be
twee
n C
isco
de
vice
s.
•Po
int-
to-P
oint
Pro
toco
l (PP
P)—
Prov
ides
con
nect
ions
bet
wee
n de
vice
s ov
er s
ever
al
type
s of
phy
sica
l int
erfa
ces
such
as
asyn
chro
nous
ser
ial,
HSS
I, I
SDN
, and
syn
chro
-no
us. P
PP w
orks
wit
h m
any
netw
ork
laye
r pr
otoc
ols,
incl
udin
g IP
and
IPX
. PPP
use
s PA
P an
d C
HA
P fo
r ba
sic
secu
rity
.•
X.2
5/Li
nk A
cces
s Pr
oced
ure,
Bal
ance
d (L
APB
)—D
efine
s co
nnec
tions
bet
wee
n D
TE
and
D
CE
for
rem
ote
term
inal
acc
ess.
LA
PB is
a d
ata
link
laye
r pr
otoc
ol s
peci
fied
by X
.25.
•Fr
ame
Rel
ay—
The
indu
stry
-sta
ndar
d, s
wit
ched
dat
a lin
k la
yer
prot
ocol
. Fra
me
Rel
ay
(bas
ed o
n X
.25)
can
han
dle
mul
tipl
e vi
rtua
l cir
cuit
s. A
sync
hron
ous
Tra
nsfe
r M
ode
(AT
M):
The
inte
rnat
iona
l sta
ndar
d fo
r ce
ll re
lay
usin
g fix
ed-l
engt
h (5
3-by
te)
cells
for
m
ulti
ple
serv
ice
type
s. F
ixed
-len
gth
cells
allo
w h
ardw
are
proc
essi
ng, w
hich
gre
atly
re
duce
s tr
ansi
t del
ays.
AT
M ta
kes
adva
ntag
e of
hig
h-sp
eed
tran
smis
sion
med
ia s
uch
as
E3,
T3,
and
SO
NE
T.
WA
N S
um
mar
y•
The
Int
erne
t is
the
inte
rcon
nect
ion
of t
hous
ands
of
larg
e an
d sm
all n
etw
orks
all
over
th
e w
orld
.•
A W
AN
is u
sed
to in
terc
onne
ct L
AN
s th
at a
re s
epar
ated
by
a la
rge
geog
raph
ic d
ista
nce.
•D
edic
ated
line
, cir
cuit
switc
hing
, pac
ket s
witc
hing
, and
cel
l sw
itchi
ng a
re s
ome
com
mon
W
AN
con
nect
ion
type
s.•
WA
N d
evic
es in
clud
e ro
uter
s, W
AN
sw
itch
es, m
odem
s, a
nd a
cces
s se
rver
s.•
WA
N p
hysi
cal p
roto
cols
des
crib
e ho
w t
o pr
ovid
e el
ectr
ical
, mec
hani
cal,
oper
atio
nal,
and
func
tion
al c
onne
ctio
n fo
r W
AN
ser
vice
s.•
WA
N d
ata
link
laye
r pr
otoc
ols
desc
ribe
how
fra
mes
are
car
ried
bet
wee
n sy
stem
s on
a
sing
le d
ata
link.
Lin
e Ty
pe
Sig
nal
Sta
nd
ard
Bit
Rat
e C
apac
ity
OC
-3SO
NE
T15
5.54
Mbp
s
OC
-9SO
NE
T46
6.56
Mbp
s
OC
-12
SON
ET
