Chapter 2 Chapter 2

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Chapter 2
Chapter 2
Point-to-Point Protocol
Point-to-Point Protocol
(PPP)
(PPP)
Part II
Part II
Chapter 2-2
CCNA4-1
Point-to-Point Protocol (PPP)
Point-to-Point Protocol (PPP)
P PP PP P C Co on nc ce ep ptts s
CCNA4-2 Chapter 2-2IIn nttr ro od du uc ciin ng g P PP PP P
•• W Wh ha att iis s P PP PP P? ?
• • R Re ec ca allll tth ha att H HD DL LC C iis s tth he e d de effa au ulltt s se er riia all e en nc ca ap ps su ulla attiio on n
method when you connect two Cisco routers.
method when you connect two Cisco routers.
• Cisco HDLC can only work with other Cisco devices.
• Cisco HDLC can only work with other Cisco devices.
• When you need to connect to a non-Cisco router, you
• When you need to connect to a non-Cisco router, you
s sh ho ou ulld d u us se e P PP PP P e en nc ca ap ps su ulla attiio on n..
• • P PP PP P iin nc cllu ud de es s m ma an ny y ffe ea attu ur re es s n no ott a av va aiilla ab blle e iin n H HD DL LC C..
• • T Th he e lliin nk k q qu ua alliitty y m ma an na ag ge em me en ntt ffe ea attu ur re e m mo on niitto or rs s tth he e
quality of the link. If too many errors are detected,
quality of the link. If too many errors are detected,
P PP PP P tta ak ke es s tth he e lliin nk k d do ow wn n..
• • P PP PP P s su up pp po or rtts s P PA AP P a an nd d C CH HA AP P a au utth he en nttiic ca attiio on n..
Chapter 2-2
CCNA4-3
Introducing PPP
Introducing PPP
• What is PPP?
• What is PPP?
• • T Th hr re ee e m ma aiin n c co om mp po on ne en ntts s::
• • H HD DL LC C::
• • H HD DL LC C p pr ro otto oc co oll ffo or r
encapsulating datagrams over point-to-point links.
encapsulating datagrams over point-to-point links.
• • L LC CP P::
• • E Ex xtte en ns siib blle e L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) ) tto o e es stta ab blliis sh h,,
configure, and test the data link connection.
configure, and test the data link connection.
• NCPs:
• NCPs:
• • F Fa am miilly y o off N Ne ettw wo or rk k C Co on nttr ro oll P Pr ro otto oc co olls s ( (N NC CP Ps s) ) ffo or r
establishing and configuring different network layer
establishing and configuring different network layer
protocols.
protocols.
CCNA4-4 Chapter 2-2IIn nttr ro od du uc ciin ng g P PP PP P
•• W Wh ha att iis s P PP PP P? ?
• • T Th hr re ee e m ma aiin n c co om mp po on ne en ntts s::
• HDLC:
• HDLC:
• HDLC protocol for
• HDLC protocol for
e en nc ca ap ps su ulla attiin ng g d da atta ag gr ra am ms s o ov ve er r p po oiin ntt- -tto o- -p po oiin ntt lliin nk ks s..
• • L LC CP P::
• Extensible Link Control Protocol (LCP) to establish,
• Extensible Link Control Protocol (LCP) to establish,
c co on nffiig gu ur re e,, a an nd d tte es stt tth he e d da atta a lliin nk k c co on nn ne ec cttiio on n..
• • N NC CP Ps s::
• Family of Network Control Protocols (NCPs) for
• Family of Network Control Protocols (NCPs) for
e es stta ab blliis sh hiin ng g a an nd d c co on nffiig gu ur riin ng g d diiffffe er re en ntt n ne ettw wo or rk k lla ay ye er r
p pr ro otto oc co olls s..
Chapter 2-2
CCNA4-5
PPP Layered Architecture
PPP Layered Architecture
Network Layer
Network Layer
IIP P IIP PX X M Ma an ny y O Otth he er rs s
Network Control Protocol (NCP)
Network Control Protocol (NCP)
Point-to-Point Protocol
Point-to-Point Protocol
Data Link Layer
Data Link Layer
( (P PP PP P) )
Link Control Protocol (LCP)
Link Control Protocol (LCP)
S Sy yn nc ch hr ro on no ou us s o or r A As sy yn nc ch hr ro on no ou us s
Physical Layer
Physical Layer
Physical Medium
Physical Medium
• PPP is a Data Link Layer protocol that provides a standard
• PPP is a Data Link Layer protocol that provides a standard
m me etth ho od d ffo or r ttr ra an ns sp po or rttiin ng g m mu ullttiip pr ro otto oc co oll d da atta ag gr ra am ms s o ov ve er r p po oiin ntt- -
tto o- -p po oiin ntt lliin nk ks s..
• Translation: IP and IPX and others, simultaneously, over a
• Translation: IP and IPX and others, simultaneously, over a
s siin ng glle e d diia allu up p o or r h hiig gh he er r s sp pe ee ed d W WA AN N lliin nk k..
CCNA4-6 Chapter 2-2P PP PP P L La ay ye er re ed d A Ar rc ch hiitte ec cttu ur re e
N Ne ettw wo or rk k L La ay ye er r
IIP P IIP PX X M Ma an ny y O Otth he er rs s
N Ne ettw wo or rk k C Co on nttr ro oll P Pr ro otto oc co olls s ( (N NC CP Ps s) )
D Da atta a L Liin nk k L La ay ye er r
L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) )
Synchronous or Asynchronous
Synchronous or Asynchronous
P Ph hy ys siic ca all L La ay ye er r
P Ph hy ys siic ca all M Me ed diiu um m
•• P PP PP P h ha as s a a lla ay ye er re ed d a ar rc ch hiitte ec cttu ur re e::
• • L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) ):: T To o e es stta ab blliis sh h,, c co on nffiig gu ur re e a an nd d
test the connection.
test the connection.
• Network Control Protocols (NCPs): A family of protocols
• Network Control Protocols (NCPs): A family of protocols
tto o e es stta ab blliis sh h a an nd d c co on nffiig gu ur re e N Ne ettw wo or rk k L La ay ye er r p pr ro otto oc co olls s..
Chapter 2-2
CCNA4-7
PPP Layered Architecture
PPP Layered Architecture
Network Layer
Network Layer
IIP P IIP PX X M Ma an ny y O Otth he er rs s
Network Control Protocols (NCPs)
Network Control Protocols (NCPs)
Data Link Layer
Data Link Layer
Link Control Protocol (LCP)
Link Control Protocol (LCP)
S Sy yn nc ch hr ro on no ou us s o or r A As sy yn nc ch hr ro on no ou us s
Physical Layer
Physical Layer
Physical Medium
Physical Medium
• PPP can be configured on multiple types of interfaces:
• PPP can be configured on multiple types of interfaces:
• • A As sy yn nc ch hr ro on no ou us s s se er riia all
• • S Sy yn nc ch hr ro on no ou us s s se er riia all
• High-Speed Serial Interface (HSSI)
• High-Speed Serial Interface (HSSI)
• Integrated Services Digital Network (ISDN)
• Integrated Services Digital Network (ISDN)
CCNA4-8 Chapter 2-2P PP PP P L La ay ye er re ed d A Ar rc ch hiitte ec cttu ur re e
N Ne ettw wo or rk k L La ay ye er r
IIP P IIP PX X M Ma an ny y O Otth he er rs s
N Ne ettw wo or rk k C Co on nttr ro oll P Pr ro otto oc co olls s ( (N NC CP Ps s) )
D Da atta a L Liin nk k L La ay ye er r
L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) )
Synchronous or Asynchronous
Synchronous or Asynchronous
P Ph hy ys siic ca all L La ay ye er r
P Ph hy ys siic ca all M Me ed diiu um m
•• P PP PP P u us se es s tth he e L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) ) tto o n ne eg go ottiia atte e a an nd d
s se ettu up p c co on nttr ro oll o op pttiio on ns s o on n tth he e W WA AN N lliin nk k..
• Authentication, Compression, Error Detection, Multilink
• Authentication, Compression, Error Detection, Multilink
ffo or r llo oa ad d b ba alla an nc ciin ng g,, P PP PP P C Ca allllb ba ac ck k a an nd d lliin nk k m mo on niitto or riin ng g
ffu un nc cttiio on ns s..
Chapter 2-2
CCNA4-9
PPP Layered Architecture
PPP Layered Architecture
Network Layer
Network Layer
IIP P IIP PX X M Ma an ny y O Otth he er rs s
Network Control Protocols (NCPs)
Network Control Protocols (NCPs)
Data Link Layer
Data Link Layer
Link Control Protocol (LCP)
Link Control Protocol (LCP)
S Sy yn nc ch hr ro on no ou us s o or r A As sy yn nc ch hr ro on no ou us s
Physical Layer
Physical Layer
Physical Medium
Physical Medium
• PPP uses the Network Control Protocols (NCPs) to permit
• PPP uses the Network Control Protocols (NCPs) to permit
m mu ullttiip plle e n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s tto o o op pe er ra atte e o on n tth he e s sa am me e
c co om mm mu un niic ca attiio on ns s lliin nk k..
CCNA4-10 Chapter 2-2P PP PP P L La ay ye er re ed d A Ar rc ch hiitte ec cttu ur re e
N Ne ettw wo or rk k L La ay ye er r
IIP P IIP PX X M Ma an ny y O Otth he er rs s
IIP PC CP P IIP PX XC CP P M Ma an ny y O Otth he er rs s
D Da atta a L Liin nk k L La ay ye er r
L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll ( (L LC CP P) )
Synchronous or Asynchronous
Synchronous or Asynchronous
P Ph hy ys siic ca all L La ay ye er r
P Ph hy ys siic ca all M Me ed diiu um m
•• F Fo or r e ev ve er ry y n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co oll u us se ed d,, a a s se ep pa ar ra atte e N Ne ettw wo or rk k
C Co on nttr ro oll P Pr ro otto oc co oll ( (N NC CP P) ) iis s p pr ro ov viid de ed d..
• NCPs include functional fields containing standardized
• NCPs include functional fields containing standardized
c co od de es s tto o iin nd diic ca atte e tth he e n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co oll tty yp pe e tth ha att
P PP PP P e en nc ca ap ps su ulla atte es s..
Chapter 2-2
CCNA4-11
FYI - PPP Protocol Suite
FYI - PPP Protocol Suite
Application
Application
P PP PP P O Ov ve er r
P Pr re es se en ntta attiio on n
C Co on nttr ro oll
E Etth he er rn ne ett
P Pr ro otto oc co olls s
S Se es ss siio on n
M Mu ullttiilliin nk k
Transport
Transport
Network
Network Multiple Network Protocols
L Liin nk k
BAP, CHAP, EAP,
ATCP ECP NBFCP
LCP, LEX, LQR,
P Pr ro otto oc co olls s
BCP IPCP OSINLCP
PPPoE
PAP
BACP IPv6CP SDCP
CCP IPXCP SNACP
Data Link
Data Link
MLP
DNCP LEXCP
PPP-BPDU
R Re em mo otte e
B Br riid dg ge es s
PPP
Physical
Physical LAN / WAN
CCNA4-12 Chapter 2-2F FY YII - - P PP PP P P Pr ro otto oc co oll S Su uiitte e
•• P PP PP P- -B BP PD DU U:: P PP PP P B Br riid dg ge e P Pr ro otto oc co oll D Da atta a U Un niitt
•• M ML LP P:: M Mu ullttiilliin nk k P PP PP P
• PPPoE: PPP Over Ethernet
• PPPoE: PPP Over Ethernet
•• L Liin nk k P Pr ro otto oc co olls s::
• • B BA AP P:: B Ba an nd dw wiid dtth h A Allllo oc ca attiio on n P Pr ro otto oc co oll
• CHAP: Challenge Handshake Authentication Protocol
• CHAP: Challenge Handshake Authentication Protocol
• EAP: Extensible Authentication Protocol
• EAP: Extensible Authentication Protocol
• • L LC CP P:: L Liin nk k C Co on nttr ro oll P Pr ro otto oc co oll
• • L LE EX X:: L LA AN N E Ex xtte en ns siio on n IIn ntte er rffa ac ce e P Pr ro otto oc co oll
• LQR: Link Quality Report
• LQR: Link Quality Report
• PAP: Password Authentication Protocol
• PAP: Password Authentication Protocol
Chapter 2-2
CCNA4-13
FYI - PPP Protocol Suite
FYI - PPP Protocol Suite
• Control Protocols:
• Control Protocols:
• • A AT TC CP P:: A Ap pp plle eT Ta allk k C Co on nttr ro oll P Pr ro otto oc co oll
• • B BA AC CP P:: B Ba an nd dw wiid dtth h A Allllo oc ca attiio on n C Co on nttr ro oll P Pr ro otto oc co oll
• • B BC CP P:: B Br riid dg giin ng g C Co on nttr ro oll P Pr ro otto oc co oll
• CCP: Compression Control Protocol
• CCP: Compression Control Protocol
• • D DN NC CP P:: D DE EC CN Ne ett P Ph ha as se e IIV V C Co on nttr ro oll P Pr ro otto oc co oll
• • E EC CP P:: E En nc cr ry yp pttiio on n C Co on nttr ro oll P Pr ro otto oc co oll
• • IIP PC CP P:: IIP P C Co on nttr ro oll P Pr ro otto oc co oll
• IPv6CP: IPv6 Control Protocol
• IPv6CP: IPv6 Control Protocol
• • IIP PX XC CP P:: N No ov ve ellll IIP PX X C Co on nttr ro oll P Pr ro otto oc co oll
• • L LE EX XC CP P:: L LA AN N E Ex xtte en ns siio on n IIn ntte er rffa ac ce e C Co on nttr ro oll P Pr ro otto oc co oll
CCNA4-14 Chapter 2-2F FY YII - - P PP PP P P Pr ro otto oc co oll S Su uiitte e
•• C Co on nttr ro oll P Pr ro otto oc co olls s::
• • N NB BF FC CP P:: N NE ET TB BIIO OS S F Fr ra am me es s C Co on nttr ro oll P Pr ro otto oc co oll
• OSINLCP: OSI Network Layer Control Protocol
• OSINLCP: OSI Network Layer Control Protocol
• SDCP: Serial Data Control Protocol
• SDCP: Serial Data Control Protocol
• • S SN NA AC CP P:: S Sy ys stte em ms s N Ne ettw wo or rk k A Ar rc ch hiitte ec cttu ur re e C Co on nttr ro oll P Pr ro otto oc co oll
Chapter 2-2
CCNA4-15
PPP Frame Structure
PPP Frame Structure
• Notice how the PPP frame has been modeled very closely on
• Notice how the PPP frame has been modeled very closely on
tth he e s stta an nd da ar rd d H HD DL LC C ffr ra am me e..
•• T Th he e p pr ro otto oc co oll ffiie elld d c co on ntta aiin ns s s sp pe ec ciiffiic c c co od de es s..
CCNA4-16 Chapter 2-2F FY YII - - P PP PP P F Fr ra am me e S Sttr ru uc cttu ur re e
•• T Th he e p pr ro otto oc co oll c co od de e d de ette er rm miin ne es s w wh ha att p pr ro otto oc co oll iin n tth he e s su uiitte e
receives the payload.
receives the payload.
P Pr ro otto oc co oll F Fiie elld d
D De es sc cr riip pttiio on n
R Ra an ng ge e ( (H He ex x) )
02xx – 1Exx
02xx – 1Exx
Not Used (compression inefficient)
xx01 – xx1F
xx01 – xx1F
0xxx – 3xxx Datagram belongs to a specific network protocol
0xxx – 3xxx
8 8x xx xx x – – B Bx xx xx x Datagram belongs to an associated NCP
4xxx – 7xxx Datagram belongs to a low-volume protocol with no NCP
4xxx – 7xxx
C Cx xx xx x - - E Ex xx xx x Datagram is a control protocol
Chapter 2-2
CCNA4-17
FYI - PPP Frame Structure
FYI - PPP Frame Structure
• Some of those codes:
• Some of those codes:
CCNA4-18 Chapter 2-2E Es stta ab blliis sh hiin ng g a a P PP PP P S Se es ss siio on n
•• P PP PP P s se es ss siio on n e es stta ab blliis sh hm me en ntt p pr ro og gr re es ss se es s tth hr ro ou ug gh h
T Th hr re ee e P Ph ha as se es s..
Chapter 2-2
CCNA4-19
Establishing a PPP Session
Establishing a PPP Session
• Phase 1 – Link Establishment:
• Phase 1 – Link Establishment:
• • T Th he e L LC CP P m mu us stt ffiir rs stt o op pe en n tth he e c co on nn ne ec cttiio on n a an nd d n ne eg go ottiia atte e
c co on nffiig gu ur ra attiio on n o op pttiio on ns s..
• Phase 2 – Determine Link Quality (Optional):
• Phase 2 – Determine Link Quality (Optional):
• The LCP tests the link to determine whether the link
• The LCP tests the link to determine whether the link
q qu ua alliitty y iis s s su uffffiic ciie en ntt tto o b br riin ng g u up p n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s..
•• P Ph ha as se e 3 3 – – N Ne ettw wo or rk k P Pr ro otto oc co oll N Ne eg go ottiia attiio on n::
• The appropriate NCP separately configures the network
• The appropriate NCP separately configures the network
lla ay ye er r p pr ro otto oc co olls s..
• • T Th he e N NC CP P c ca an n b br riin ng g tth he em m u up p a an nd d tta ak ke e tth he em m d do ow wn n a att a an ny y
time.
time.
CCNA4-20 Chapter 2-2E Es stta ab blliis sh hiin ng g a a L Liin nk k w wiitth h L LC CP P
•• P Ph ha as se e 1 1 – – L Liin nk k E Es stta ab blliis sh hm me en ntt::
• • IIn n tth hiis s p ph ha as se e e ea ac ch h P PP PP P d de ev viic ce e s se en nd ds s L LC CP P ffr ra am me es s tto o
configure and test the data link.
configure and test the data link.
• LCP frames contain a configuration option field that
• LCP frames contain a configuration option field that
a allllo ow ws s d de ev viic ce es s tto o n ne eg go ottiia atte e tth he e u us se e o off o op pttiio on ns s s su uc ch h a as s::
• • T Th he e m ma ax xiim mu um m ttr ra an ns sm miis ss siio on n u un niitt ( (M MT TU U) )
• • C Co om mp pr re es ss siio on n o off c ce er rtta aiin n P PP PP P ffiie elld ds s
• The link-authentication protocol.
• The link-authentication protocol.
Chapter 2-2
CCNA4-21
Establishing a Link with LCP
Establishing a Link with LCP
•• IIff a a c co on nffiig gu ur ra attiio on n
o op pttiio on n iis s n no ott
included in an LCP
included in an LCP
p pa ac ck ke ett,, tth he e d de effa au ulltt
v va allu ue e iis s a as ss su um me ed d..
•• B Be effo or re e a an ny y n ne ettw wo or rk k lla ay ye er r p pa ac ck ke etts s c ca an n b be e e ex xc ch ha an ng ge ed d,, L LC CP P
must first open the connection and negotiate the
must first open the connection and negotiate the
c co on nffiig gu ur ra attiio on n p pa ar ra am me ette er rs s..
•• T Th hiis s p ph ha as se e iis s c co om mp plle ette e w wh he en n a a c co on nffiig gu ur ra attiio on n
acknowledgment frame has been sent and received.
acknowledgment frame has been sent and received.
CCNA4-22 Chapter 2-2E Es stta ab blliis sh hiin ng g a a L Liin nk k w wiitth h L LC CP P
•• A Au utth he en nttiic ca attiio on n::
• • A Afftte er r tth he e lliin nk k h ha as s b be ee en n e es stta ab blliis sh he ed d a an nd d tth he e
authentication protocol decided on, the peer may be
authentication protocol decided on, the peer may be
a au utth he en nttiic ca atte ed d..
• • A Au utth he en nttiic ca attiio on n,, iiff u us se ed d,, tta ak ke es s p plla ac ce e b be effo or re e tth he e n ne ettw wo or rk k
layer protocol phase is entered.
layer protocol phase is entered.
Chapter 2-2
CCNA4-23
Establishing a Link with LCP
Establishing a Link with LCP
• As part of this phase, LCP also allows for an optional link-
• As part of this phase, LCP also allows for an optional link-
q qu ua alliitty y d de ette er rm miin na attiio on n tte es stt..
• • T Th he e lliin nk k iis s tte es stte ed d tto o d de ette er rm miin ne e w wh he etth he er r tth he e lliin nk k q qu ua alliitty y iis s
good enough to bring up network layer protocols.
good enough to bring up network layer protocols.
CCNA4-24 Chapter 2-2N Ne ettw wo or rk k L La ay ye er r P Pr ro otto oc co oll N Ne eg go ottiia attiio on n
•• P PP PP P p pe er rm miitts s m mu ullttiip plle e N Ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s tto o o op pe er ra atte e o on n
tth he e s sa am me e c co om mm mu un niic ca attiio on ns s lliin nk k..
• For every Network layer protocol used, PPP uses a
• For every Network layer protocol used, PPP uses a
s se ep pa ar ra atte e N NC CP P m mo od du ulle e..
• • IIP P u us se es s tth he e IIP PC CP P m mo od du ulle e..
• IP Version 6 uses the IPv6CP module.
• IP Version 6 uses the IPv6CP module.
• IPX uses the IPXCP module.
• IPX uses the IPXCP module.
Chapter 2-2
CCNA4-25
Network Layer Protocol Negotiation
Network Layer Protocol Negotiation
• In this phase the PPP devices send NCP packets to choose
• In this phase the PPP devices send NCP packets to choose
a an nd d c co on nffiig gu ur re e o on ne e o or r m mo or re e n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s ( (e e..g g.. IIP P) )..
•• O On nc ce e e ea ac ch h o off tth he e c ch ho os se en n n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s h ha as s b be ee en n
configured, packets from each network layer protocol can be
configured, packets from each network layer protocol can be
s se en ntt o ov ve er r tth he e lliin nk k..
•• IIff L LC CP P c cllo os se es s tth he e lliin nk k,, iitt iin nffo or rm ms s tth he e n ne ettw wo or rk k lla ay ye er r p pr ro otto oc co olls s
so that they can take appropriate action.
so that they can take appropriate action.
CCNA4-26 Chapter 2-2Network Layer Protocol Negotiation
Network Layer Protocol Negotiation
LCP open = connection made.
LCP open = connection made.
NCPs
NCPs
•• T Th he e sshhooww iinntteerrffaacceess c co om mm ma an nd d r re ev ve ea alls s tth he e L LC CP P a an nd d
N NC CP P s stta atte es s u un nd de er r P PP PP P c co on nffiig gu ur ra attiio on n..
Chapter 2-2
CCNA4-27
FYI - PPP Configuration Options
FYI - PPP Configuration Options
CCNA4-28 Chapter 2-2P PP PP P C Co on nffiig gu ur ra attiio on n C Co om mm ma an nd ds s
•• E En na ab blliin ng g P PP PP P::
Router#config t
Router#config t
RRoouutteerr((ccoonnffiigg))##iinntteerrffaaccee ss00//22//00
Router(config-if)#encapsulation ppp
Router(config-if)#encapsulation ppp
•• C Co on nffiig gu ur riin ng g C Co om mp pr re es ss siio on n::
• • Y Yo ou u c ca an n c co on nffiig gu ur re e p po oiin ntt- -tto o- -p po oiin ntt c co om mp pr re es ss siio on n o on n s se er riia all
interfaces after you have enabled PPP. Because this
interfaces after you have enabled PPP. Because this
o op pttiio on n iin nv vo ok ke es s a a s so offttw wa ar re e c co om mp pr re es ss siio on n p pr ro oc ce es ss s,, iitt c ca an n
a affffe ec ctt s sy ys stte em m p pe er rffo or rm ma an nc ce e.. IIff tth he e ttr ra affffiic c a allr re ea ad dy y c co on ns siis stts s
of compressed files (.zip, .tar, or .mpeg, for example), do
of compressed files (.zip, .tar, or .mpeg, for example), do
n no ott u us se e tth hiis s o op pttiio on n..
RRoouutteerr((ccoonnffiigg--iiff))##ccoommpprreessss [[pprreeddiiccttoorr||ssttaacc]]
Chapter 2-2
CCNA4-29
PPP Configuration Commands
PPP Configuration Commands
• Link Quality Monitoring:
• Link Quality Monitoring:
• • L LC CP P p pr ro ov viid de es s a an n o op pttiio on na all lliin nk k q qu ua alliitty y d de ette er rm miin na attiio on n
d du ur riin ng g tth he e L LC CP P N Ne eg go ottiia attiio on n..
• If the link quality percentage is not maintained, the link is
• If the link quality percentage is not maintained, the link is
deemed to be of poor quality and is taken down.
deemed to be of poor quality and is taken down.
RRoouutteerr((ccoonnffiigg--iiff))##pppppp qquuaalliittyy ppeerrcceennttaaggee
• Load Balancing Across Links:
• Load Balancing Across Links:
• Multilink PPP (also referred to as MP, MPPP, MLP, or
• Multilink PPP (also referred to as MP, MPPP, MLP, or
M Mu ullttiilliin nk k) ) p pr ro ov viid de es s a a m me etth ho od d ffo or r s sp pr re ea ad diin ng g ttr ra affffiic c a ac cr ro os ss s
multiple physical WAN links.
multiple physical WAN links.
Router(config-if)#ppp multilink
Router(config-if)#ppp multilink
CCNA4-30 Chapter 2-2V Ve er riiffy yiin ng g a a S Se er riia all P PP PP P C Co on nffiig gu ur ra attiio on n
•• U Us se e tth he e sshhooww iinntteerrffaacceess sseerriiaall c co om mm ma an nd d tto o v ve er riiffy y
p pr ro op pe er r c co on nffiig gu ur ra attiio on n P PP PP P e en nc ca ap ps su ulla attiio on n..
• When you configure PPP, the output of the show
• When you configure PPP, the output of the show
iin ntte er rffa ac ce es s s se er riia all c co om mm ma an nd d s sh ho ou ulld d s sh ho ow w " "e en nc ca ap ps su ulla attiio on n
p pp pp p" "..
• When you configure PPP, you can check its LCP and
• When you configure PPP, you can check its LCP and
N NC CP P s stta atte es s..
Chapter 2-2
CCNA4-31
Troubleshooting PPP Encapsulation
Troubleshooting PPP Encapsulation
CCNA4-32 Chapter 2-2P Po oiin ntt- -tto o- -P Po oiin ntt P Pr ro otto oc co oll ( (P PP PP P) )
PPP Authentication
PPP Authentication
Chapter 2-2
CCNA4-33
PPP Authentication Protocol - PAP
PPP Authentication Protocol - PAP
• Password Authentication Protocol (PAP):
• Password Authentication Protocol (PAP):
• • N No ott a a s sttr ro on ng g p pr ro otto oc co oll..
• • U Us se er rn na am me e//P Pa as ss sw wo or rd d s se en ntt iin n c clle ea ar r tte ex xtt..
• Uses a two-way handshake.
• Uses a two-way handshake.
• Remote node in control of attempts.
• Remote node in control of attempts.
• Username/Password pair are repeatedly sent across
• Username/Password pair are repeatedly sent across
the link until authentication is acknowledged or the
the link until authentication is acknowledged or the
lliin nk k iis s tte er rm miin na atte ed d..
CCNA4-34 Chapter 2-2Configuring PAP
Configuring PAP
Rtr(config)#username remote-host
Rtr(config)#username remote-host
password remote-password
password remote-password
•• T Th hiis s n ne ee ed ds s tto o m ma attc ch h tth he e p pp pp p p pa ap p s se en ntt- -u us se er rn na am me e a an nd d
p pa as ss sw wo or rd d o on n tth he e r re em mo otte e h ho os stt..
•• W Wh he en n r re ec ce eiiv ve ed d a an nd d v va alliid da atte ed d,, r ro ou utte er rs s w wiitth h tth he es se e
u us se er rn na am me e//p pa as ss sw wo or rd d c co om mb biin na attiio on ns s w wiillll b be e a allllo ow we ed d tto o
c co on nn ne ec ctt..
RRttrr((ccoonnffiigg--iiff))##pppppp ppaapp
sseenntt--uusseerrnnaammee llooccaall--hhoosstt--uusseerrnnaammee
ppaasssswwoorrdd llooccaall--hhoosstt--ppaasssswwoorrdd
•• T Th he e p pa as ss sw wo or rd ds s d do o n no ott h ha av ve e tto o b be e tth he e s sa am me e o on n tth he e r re em mo otte e
and the local routers.
and the local routers.
• It should not be the same as the enable-secret password.
• It should not be the same as the enable-secret password.
Chapter 2-2
CCNA4-35
R Re em mo otte e
hostname SantaCruz
PAP
PAP
u us se er rn na am me es s a an nd d
username HQ password HQpass
p pa as ss sw wo or rd ds s
interface serial 0/2/0
ip address 172.25.3.5 255.255.255.252
encapsulation ppp
ppp authentication pap
ppp pap sent-username SantaCruz
password SantaCruzpass
hostname HQ
username SantaCruz password SantaCruzpass
interface serial 0/2/0
ip address 172.25.3.6 255.255.255.252
encapsulation ppp
ppp authentication pap
L Lo oc ca all
ppp pap sent-username HQ
u us se er rn na am me es s a an nd d
password HQpass
p pa as ss sw wo or rd ds s
CCNA4-36 Chapter 2-21. Establish PPP Link
1. Establish PPP Link
2. Configuration request for PAP
2. Configuration request for PAP
authentication.
authentication.
1
1
3. Configuration ACK.
3. Configuration ACK.
2
2
4. SantaCruz sends the
4. SantaCruz sends the
SantaCruz username and
SantaCruz username and
SantCruzpass password
SantCruzpass password
3
3
configured for the interface.
configured for the interface.
5. HQ looks up the received name,
5. HQ looks up the received name,
4
4
retrieves the password and
retrieves the password and
compares configured to received.
compares configured to received.
5
ACK 5
ACK
6. If they are the same, send an
6. If they are the same, send an
ACK and allow access.
ACK and allow access.
6
6
If they are not the same, send a
If they are not the same, send a
NACK and terminate the
NACK and terminate the
NACK
NACK
connection.
connection.
Chapter 2-2
CCNA4-37
PPP Authentication Protocol - CHAP
PPP Authentication Protocol - CHAP
• Challenge Handshake Authentication Protocol (CHAP):
• Challenge Handshake Authentication Protocol (CHAP):
• • T Th he e p pr re effe er rr re ed d a au utth he en nttiic ca attiio on n p pr ro otto oc co oll..
• • U Us se es s a a tth hr re ee e- -w wa ay y h ha an nd ds sh ha ak ke e..
• • C Ch ha alllle en ng ge e//R Re es sp po on ns se e m me es ss sa ag ge es s u us se e M MD D5 5 h ha as sh hiin ng g o on n
random values and the password.
random values and the password.
• • C Ch ha alllle en ng ge e//R Re es sp po on ns se e s se eq qu ue en nc ce e r re ep pe ea atte ed d a att r ra an nd do om m
p pe er riio od ds s d du ur riin ng g tth he e c co on nn ne ec ctt..
CCNA4-38 Chapter 2-2PPP Authentication Protocol - CHAP
PPP Authentication Protocol - CHAP
•• C CH HA AP P p pr ro ov viid de es s p pr ro otte ec cttiio on n a ag ga aiin ns stt p plla ay yb ba ac ck k a atttta ac ck k tth hr ro ou ug gh h
tth he e u us se e o off a a v va ar riia ab blle e a an nd d h ha as sh he ed d c ch ha alllle en ng ge e v va allu ue e tth ha att iis s
unique and unpredictable.
unique and unpredictable.
•• T Th he e u us se e o off r re ep pe ea atte ed d c ch ha alllle en ng ge es s iis s iin ntte en nd de ed d tto o lliim miitt tth he e ttiim me e
o off e ex xp po os su ur re e tto o a an ny y s siin ng glle e a atttta ac ck k..
• Unlike PAP, the local router or a third-party authentication
• Unlike PAP, the local router or a third-party authentication
s se er rv ve er r iis s iin n c co on nttr ro oll o off tth he e ffr re eq qu ue en nc cy y a an nd d ttiim miin ng g o off tth he e
c ch ha alllle en ng ge es s..
Chapter 2-2
CCNA4-39
PPP Authentication – CHAP Challenge
PPP Authentication – CHAP Challenge
• SantaCruz calls HQ and establishes a ppp link.
• SantaCruz calls HQ and establishes a ppp link.
• A CHAP challenge packet is built by the HQ router with the
• A CHAP challenge packet is built by the HQ router with the
ffo ollllo ow wiin ng g c ch ha ar ra ac ctte er riis sttiic cs s::
• • 0 01 1 = = c ch ha alllle en ng ge e p pa ac ck ke ett tty yp pe e iid de en nttiiffiie er r..
• • IID D = = s se eq qu ue en nttiia all n nu um mb be er r tth ha att iid de en nttiiffiie es s tth he e c ch ha alllle en ng ge e..
• random = a reasonably random number generated by
• random = a reasonably random number generated by
the router.
the router.
• HQ = the authentication name of the challenger.
• HQ = the authentication name of the challenger.
CCNA4-40 Chapter 2-2CHAP Challenge
CHAP Challenge
• • T Th he e IID D a an nd d r ra an nd do om m v va allu ue es s a ar re e k ke ep ptt o on n tth he e H HQ Q r ro ou utte er r o or r tth he e
c ca alllle ed d r ro ou utte er r..
• The challenge packet is sent to the calling router.
• The challenge packet is sent to the calling router.
• A list of outstanding challenges is maintained.
• A list of outstanding challenges is maintained.
Chapter 2-2
CCNA4-41
CHAP Challenge
CHAP Challenge
Receive
Receive
C CH HA AP P
C Ch ha alllle en ng ge e
• The name HQ is used to look up the password.
• The name HQ is used to look up the password.
• The ID value, the random value and the password are fed
• The ID value, the random value and the password are fed
iin ntto o tth he e M MD D5 5 h ha as sh h g ge en ne er ra atto or r..
• The result is the one-way MD5-hashed CHAP challenge that
• The result is the one-way MD5-hashed CHAP challenge that
w wiillll b be e s se en ntt b ba ac ck k iin n tth he e C CH HA AP P r re es sp po on ns se e..
CCNA4-42 Chapter 2-2CHAP Challenge
CHAP Challenge
C CH HA AP P
Response
Response
• • T Th he e r re es sp po on ns se e p pa ac ck ke ett iis s a as ss se em mb blle ed d a an nd d s se en ntt..
• • 0 02 2 = = C CH HA AP P r re es sp po on ns se e p pa ac ck ke ett tty yp pe e iid de en nttiiffiie er r..
• ID = copied from the challenge packet.
• ID = copied from the challenge packet.
• hash = the output from the MD5 hash generator.
• hash = the output from the MD5 hash generator.
• • S Sa an ntta aC Cr ru uz z = = tth he e h ho os sttn na am me e o off tth he e r re es sp po on nd diin ng g d de ev viic ce e..
( (F Fr ro om m tth he e hhoossttnnaammee c co om mm ma an nd d o or r tth he e
pppppp cchhaapp hhoossttnnaammee c co om mm ma an nd d) )..
Chapter 2-2
CCNA4-43
CHAP Challenge
CHAP Challenge
Receive
Receive
C CH HA AP P
R Re es sp po on ns se e
• The ID is used to find the original challenge packet.
• The ID is used to find the original challenge packet.
• The name is used to look up the password from a configured
• The name is used to look up the password from a configured
n na am me e o or r a a s se ec cu ur riitty y s se er rv ve er r..
• The original ID, the original random value and the password
• The original ID, the original random value and the password
a ar re e ffe ed d iin ntto o tth he e M MD D5 5 h ha as sh h g ge en ne er ra atto or r..
CCNA4-44 Chapter 2-2CHAP Challenge
CHAP Challenge
R Re ec ce eiiv ve e
CHAP
CHAP
Response
Response
• • T Th he e h ha as sh h v va allu ue e r re ec ce eiiv ve ed d iin n tth he e r re es sp po on ns se e p pa ac ck ke ett iis s tth he en n
c co om mp pa ar re ed d tto o tth he e c ca allc cu ulla atte ed d M MD D5 5 h ha as sh h v va allu ue e..
• CHAP authentication succeeds if the calculated and the
• CHAP authentication succeeds if the calculated and the
r re ec ce eiiv ve ed d h ha as sh h v va allu ue es s a ar re e e eq qu ua all..
Chapter 2-2
CCNA4-45
CHAP Challenge
CHAP Challenge
W We ellc co om me e IIn n
0 03 3
Success
Success
O OR R
F Fa aiillu ur re e
• If authentication is successful, a CHAP success packet is
• If authentication is successful, a CHAP success packet is
b bu uiilltt ffr ro om m tth he e ffo ollllo ow wiin ng g c co om mp po on ne en ntts s::
• • 0 03 3 = = C CH HA AP P s su uc cc ce es ss s m me es ss sa ag ge e tty yp pe e..
• ID = copied from the response packet.
• ID = copied from the response packet.
• “Welcome In” is simply a text message providing a user-
• “Welcome In” is simply a text message providing a user-
r re ea ad da ab blle e e ex xp plla an na attiio on n..
CCNA4-46 Chapter 2-2CHAP Challenge
CHAP Challenge
W We ellc co om me e IIn n
W We ellc co om me e IIn n
0 03 3
0 03 3
S Su uc cc ce es ss s
OR
OR
Failure
Failure Authentication Failed
Authentication Failed
04
04
• • IIff a au utth he en nttiic ca attiio on n ffa aiills s,, a a C CH HA AP P ffa aiillu ur re e p pa ac ck ke ett iis s b bu uiilltt ffr ro om m tth he e
ffo ollllo ow wiin ng g c co om mp po on ne en ntts s::
• 04 = CHAP failure message type.
• 04 = CHAP failure message type.
• ID = copied from the response packet.
• ID = copied from the response packet.
• • “ “A Au utth he en nttiic ca attiio on n ffa aiillu ur re e” ” o or r o otth he er r tte ex xtt m me es ss sa ag ge e,, p pr ro ov viid diin ng g
a user-readable explanation.
a user-readable explanation.
Chapter 2-2
CCNA4-47
PPP Configuration Command Summary
PPP Configuration Command Summary
Router(config)#username name password password
Router(config)#interface serial 0/2/0
Router(config-if)#ip address address subnetmask
Router(config-if)#encapsulation ppp
Router(config-if)#ppp authentication chap
OR
Router(config-if)#ppp authentication pap
Router(config-if)#ppp pap sent-username name
password password
CCNA4-48 Chapter 2-2debug ppp Command Summary
debug ppp Command Summary
•• ddeebbuugg pppppp aarrgguummeenntt
•• ddeebbuugg pppppp aauutthheennttiiccaattiioonn
• Display the authentication exchange sequence.
• Display the authentication exchange sequence.
• debug ppp chap
• debug ppp chap
• • D Diis sp plla ay y C CH HA AP P p pa ac ck ke ett e ex xc ch ha an ng ge es s..
•• ddeebbuugg pppppp eerrrroorr
• Display protocol errors and error statistics.
• Display protocol errors and error statistics.
• debug ppp negotiation
• debug ppp negotiation
• • D Diis sp plla ay y p pa ac ck ke etts s d du ur riin ng g c co on nn ne ec cttiio on n e es stta ab blliis sh hm me en ntt..
•• ddeebbuugg pppppp ppaacckkeett
• Display packets being sent and received.
• Display packets being sent and received.
Chapter 2-2
CCNA4-49