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8/14/2019 Establlishing Serial Point to Point Connection
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Chapter 12
Establishing SerialPoint-to-PointConnections
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Upon completion of this chapter, you will beable to perform the following tasks:
Configure HDLC and PPP protocols on a
serial WAN connection
Configure PAP and CHAP authentication on aPPP connection
Verify proper point-to-point HDLC and PPPconfiguration
Objectives
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WAN Overview
ServiceProvider
WANs connect sites
Connection requirements vary depending on
user requirements and cost
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Leased Line
Synchronous serial
Telephone
CompanyCircuit-switched
Asynchronous serial,
ISDN Layer 1
Service
ProviderPacket-switched
Synchronous serial
WAN Connection Types:Layer 1
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Point-to-point orcircuit-switched
connection
CO Switch
Customer PremisesEquipment
Demarcation
Local Loop
WAN service provider toll network
Trunks and switches
Interfacing WAN ServiceProviders
Provider assigns connection parameters tosubscriber
S S
S SS
S S
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Serial Point-to-PointConnections
Router connections
Network connections at the CSU/DSU
EIA/TIA-232 EIA/TIA-449 EIA-530V.35 X.21
CSU/DSU
End userdevice
ServiceProvider
DTE
DCE
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Leased Line
Circuit-switched
PPP, SLIP, HDLC
HDLC, PPP, SLIP
Packet-switched
X.25, Frame Relay, ATM
Typical WAN EncapsulationProtocols: Layer 2
Telephone
Company
Service
Provider
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Flag Address Control Data FCS Flag
HDLC
Supports only single protocol environments
Flag Address Control Proprietary Data FCS Flag
Cisco HDLC
HDLC Frame Format
Ciscos HDLC has a proprietary data field to supportmultiprotocol environments
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HDLC Command
Router(config-if)#encapsulation hdlc
Enable hdlc encapsulation
HDLC is the default encapsulation onsynchronous serial interfaces
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PPP EncapsulationTCP/IPNovell IPXAppleTalk
Multiple protocolencapsulations using
NCPs in PPP
PPP can carry packets from several protocol suitesusing Network Control Programs
PPP controls the setup of several link options usingLCP
Link setup and controlusing LCP in PPP
An Overview of PPP
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Feature How It Operates Protocol
Authentication PAP
CHAPPerform Challenge Handshake
Require a password
CompressionCompress data at source;reproduce data atdestination
Stacker orPredictor
ErrorDetection
Avoid frame looping
Monitor data dropped on link
Multilink Load balancing acrossmultiple links
MultilinkProtocol (MP)
PPP LCP Configuration Options
Quality
Magic Number
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PPP Authentication Overview
Two PPP authentication protocols:PAP and CHAP
PPP Session Establishment1 Link Establishment Phase2 Optional Authentication Phase3 Network-Layer Protocol Phase
Dialup orCircuit-Switched
Network
S l i PPP A h i i
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Passwords sent in clear text
Peer in control of attempts
Selecting a PPP AuthenticationProtocol
Remote Router(SantaCruz)
Central-Site Router(HQ)
Hostname: santacruzPassword: boardwalk
username santacruzpassword boardwalk
PAP2-Way Handshake
santacruz, boardwalk
Accept/Reject
S l i PPP A h i i
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Selecting a PPP AuthenticationProtocol (cont.)
Remote Router(SantaCruz)
Central-Site Router(HQ)
Hostname: santacruzPassword: boardwalk
username santacruzpassword boardwalk
CHAP3-Way Handshake
Challenge
Response
Accept/Reject
Use secret known only to authenticatorand peer
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Configuring PPP andAuthentication Overview
ServiceProvider
Verify whoyou are.
Router to BeAuthenticated(The router that initiated the call.)
ppp encapsulation
hostname
username / password
ppp authentication
Authenticating Router(The router that received the call.)
ppp encapsulation
hostname
username / password
ppp authentication
Enabling PPP
Enabling PPP Authentication
Enabling PPP
Enabling PPP Authentication
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Configuring PPP
Router(config-if)#encapsulation ppp
Enable PPP encapsulation
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Configuring PPP Authentication
Router(config)#hostname name
Assigns a host name to your router
Router(config)#username name passwordpassword
Identifies the username and password ofauthenticating router
C fi i PPP A th ti ti
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Configuring PPP Authentication(cont.)
Router(config-if)#ppp authentication{chap | chap pap | pap chap | pap}
Enables PAP and/or CHAP authentication
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Configuring CHAP Example
hostname left
username right password sameone
!
int serial 0
ip address 10.0.1.1 255.255.255.0
encapsulation ppp
ppp authentication CHAP
hostname right
username left password sameone
!
int serial 0
ip address 10.0.1.2 255.255.255.0
encapsulation ppp
ppp authentication CHAP
Leftrouter
Rightrouter
PSTN/ISDN
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Verifying HDLC and PPPEncapsulation Configuration
Router#show interface s0
Serial0 is up, line protocol is up
Hardware is HD64570
Internet address is 10.140.1.2/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation PPP, loopback not set, keepalive set (10 sec)
LCP Open
Open: IPCP, CDPCPLast input 00:00:05, output 00:00:05, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
38021 packets input, 5656110 bytes, 0 no bufferReceived 23488 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
38097 packets output, 2135697 bytes, 0 underruns
0 output errors, 0 collisions, 6045 interface resets
0 output buffer failures, 0 output buffers swapped out
482 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
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Verifying PPP Authentication with thedebug ppp authenticationCommand
4d20h: %LINK-3-UPDOWN: Interface Serial0, changed state to up
4d20h: Se0 PPP: Treating connection as a dedicated line
4d20h: Se0 PPP: Phase is AUTHENTICATING, by both
4d20h: Se0 CHAP: O CHALLENGE id 2 len 28 from left"
4d20h: Se0 CHAP: I CHALLENGE id 3 len 28 from right"
4d20h: Se0 CHAP: O RESPONSE id 3 len 28 from left"
4d20h: Se0 CHAP: I RESPONSE id 2 len 28 from right"
4d20h: Se0 CHAP: O SUCCESS id 2 len 44d20h: Se0 CHAP: I SUCCESS id 3 len 4
4d20h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0,
changed state to up
debug ppp authenticationsuccessful CHAP output
Leftrouter
Rightrouter
ServiceProvider
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Visual Objective
pod ros s0A 10.140.1.2B 10.140.2.2C 10.140.3.2D 10.140.4.2E 10.140.5.2
F 10.140.6.2G 10.140.7.2H 10.140.8.2I 10.140.9.2J 10.140.10.2K 10.140.11.2L 10.140.12.2
s1/0 - s2/310.140.1.1 10.140.12.1
core_ server10.1.1.1
wg_sw_a10.2.2.11
wg_sw_l10.13.13.11
wg_pc_a10.2.2.12
wg_pc_l10.13.13.12
wg_ro_ae0/1 e0/2
e0/2e0/1
e0
e0
fa0/23
core_sw_a10.1.1.2
wg_ro_l
core_ro10.1.1.3
fa0/24 fa0/0
LL
s010.140.1.2
...
10.13.13.3
s0
10.140.12.2
PPP with CHAP
PPP with CHAP
10.2.2.3
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After completing this chapter, you should beable to perform the following tasks:
Select an appropriate WAN connectionbased on your requirements
Configure HDLC and PPP encapsulationmethods on your point-to-point WAN
connection
Configure CHAP authentication on a PPPconnection
Summary
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1. What are three types of WAN connectionsyou can enable on a Cisco router?
2. What are two examples of point-to-pointencapsulation protocols and what are theadvantages of each?
3. What are some of the PPP LCP options?
Review Questions
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Chapter 12
Establishing SerialPoint-to-PointConnections
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Objectives
Upon completion of this chapter, you willbe able to perform the following tasks:
Describe the components that make up ISDNconnectivity
Configure ISDN BRI and legacy dial-on-demand routing (DDR)
Verify DDR operation
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What is ISDN?
Providernetwork
DigitalPBX
Small office
Home office
Voice, data, video, and special services
Telecommuter
Central site
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Standards from the ITU (formerly CCITT)
ISDN Standards
Protocol Key Examples
TelephoneNetwork andISDN
ISDN Concepts,Aspects, andInterfaces
Switching andSignaling
I-Series
Q.921LAPD (Link Access Procedureon the D channel)
Q.931ISDN Network Layer betweenTerminal and Switch
Q-Series
Issue
E-SeriesE.163International Telephone
Numbering PlanE.164International ISDN Addressing
I.100 SeriesConcepts, Structures,Terminology
I.400User-Network Interfaces (UNIs)
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BRI and PRI are used globally for ISDN
Channel Mostly Used for
B Circuit-switched data (HDLC, PPP)
Capacity
64 kbps
D 2BService
providernetwork
NT1
ISDN Access Options
Signaling information (LAPD)D 16/64 kbps
CSU/DSU
23 or 30B
BRI
PRI
D
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BRI Call Processing
ISDN
service provider
4
B channel(s)
D channel/SS7 signaling
2 SS7
ISDNSwitch
ISDNSwitch
ISDN Functions and Reference
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ISDN Functions and ReferencePoints
Functions are devices orhardware
Reference points aredemarcations or interfaces
NT1
TATE2
TE1 NT2
Localloop
ExistingTerminal
ISDN Terminal
Terminal
Adapter
R
S T UService
providernetwork
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Cisco ISDN BRI Interfaces
TA
S/T
R
Service
provider
network
Native ISDN interfaceint bri 0
Nonnative ISDN interfaceint serial 0(EIA/TIA-232, V.35, X.21)
NT1
NT1S0
S/T
bri 0
U
bri 0
TE1
NT1
TE1 TE2
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Many providers and switch types
Services vary by regions and countries
ISDN Switch Types
CO CO
S
S
S
S S
S S
S S
S
S
S S
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Router(config)#isdn switch-type switch-type
Configuring ISDN BRI
Specifies the type of ISDN switch withwhich the router communicates
Other configuration requirements vary forspecific providers
Step 1: Specify the ISDN switch type
Router(config-if)#isdn switch-type switch-type
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Sets a B channel SPID required by many serviceproviders
Configuring ISDN BRI (cont.)
Step 2: (Optional) Setting SPIDs
Sets a SPID for the second B channel
Router(config-if)#isdn spid1 spid-number[ ldn ]
Router(config-if)#isdn spid2 spid-number[ ldn ]
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Written Exercise
Local LoopCustomer Premises Service Provider
BRI 0
S 0
Label the functional elements and reference points
W i E i A
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Written Exercise: Answers
Local LoopCustomer Premises Service Provider
NT1BRI 0
S 0NT1TA
U
U
S/T
S/TR
Label the functional elements and reference points
Wh I Di l D d
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What Is Dial-on-DemandRouting?
PSTN
ISDNI need to senddata to Dallas.
DallasCorporate
Chicago
Connect when needed
Disconnect when finished
ISDN or PSTN
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When to Use DDR
Headquarters
Telecommuter
VendorPeriodic connections
Small amounts of data
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Generic DDR Operation
1. Route to destination is determined
DCE
Interestingpacket arrives
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Generic DDR Operation
1. Route to destination is determined
2. Interesting packets dictate DDR call
DCE
Interestingpacket arrives
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Generic DDR Operation
1. Route to destination is determined
2. Interesting packets dictate DDR call
3. Dialer information is looked up
Interestingpacket arrives
Dial connection
ISDN orBasic
Service
DCE
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1. Route to destination is determined
2. Interesting packets dictate DDR call
3. Dialer information is looked up
4. Traffic is transmitted
5. Call is terminated
Generic DDR Operation
Interestingpacket arrives
Dial connection
ISDN orBasic
Service
DCE
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Configuring Legacy DDR
1 Define static routesWhat route do I use?
Interestingpacket arrives
DCE
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3
1
2
Define static routesWhat route do I use?
Specify interesting trafficWhat trafficenables the link?
Configure the dialer informationWhatnumber do I call?
Configuring DDR
Interestingpacket arrives
Dial connection
ISDN orBasic
Service
DCE
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Task 2: Specifying Interesting Traffic
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Task 2: Specifying Interesting Traffic(What Enables the Connection?)
dialer-list 1 protocol ip permit
dialer-list 1 protocol ip list 101
access-list 101 deny tcp any any eq ftpaccess-list 101 deny tcp any any eq telnet
access-list 101 permit ip any any
Any IP traffic will initiate the link
Any IP traffic, except FTP and Telnet, will initiate the link
Deny FTPDeny Telnet
Without Access Lists
With Access Lists (for better control)
Task 3: Configuring the
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Task 3: Configuring theDialer Information
Applies rulesdefined by dialer-listto individual
interfaces
hostname Home
!
isdn switch-type basic-5ess
!
username central password cisco
interface BRI0
ip address 10.1.0.1 255.255.255.0
encapsulation ppp
dialer idle-timeout 180
dialer map ip 10.1.0.2 name Central 5552000
dialer-group 1
no fair-queue
ppp authentication chap
!
router ripnetwork 10.0.0.0
!
no ip classless
ip route 10.10.0.0 255.255.0.0 10.1.0.2
ip route 10.20.0.0 255.255.0.0 10.1.0.2
!
dialer-list 1 protocol ip permit
Both valuesmust match
Task 3: Configuring the
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Central
Task 3: Configuring theDialer Information (cont.)
How do I get tosubnetwork 10.10.0.0?
Number to dial
Remote host nameUsed for PPP CHAP
interface BRI0
ip address 10.1.0.1 255.255.255.0
encapsulation ppp
dialer idle-timeout 180dialer map ip 10.1.0.2 name Central 5552000
dialer-group 1
no fair-queue
ppp authentication chap
ISDNHome10.1.0.1
bri 0
5551000
bri 0
5552000
10.1.0.2 Subnets10.10.0.010.20.0.0
Legacy DDR Configuration
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Legacy DDR ConfigurationTasks Summarized
1
3
2
hostname Home!
isdn switch-type basic-5ess
!
username central password cisco
interface BRI0
ip address 10.1.0.1 255.255.255.0
encapsulation pppdialer idle-timeout 180
dialer map ip 10.1.0.2 name Central 5552000
dialer-group 1
no fair-queue
ppp authentication chap
!
router ripnetwork 10.0.0.0
!
no ip classless
ip route 10.10.0.0 255.255.0.0 10.1.0.2
ip route 10.20.0.0 255.255.0.0 10.1.0.2
dialer-list 1 protocol ip permit
!
Optional Legacy DDR
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Establishes the amount of traffic on linkbefore a second link is enabled
Establishes the idle time before disconnect
ter(config-if)#dialer idle-timeout seconds
Optional Legacy DDRCommands
ter(config-if)#dialer load-threshold load
utbound | inbound | either ]
Legacy DDR Using ACLs
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access-list 101 permit tcp any any eq smtp
access-list 101 permit tcp any any eq telnet
dialer-list 1 list 101
!
ip route 192.168.12.0 255.255.255.0 10.108.126.2
ip route 192.168.14.0 255.255.255.0 10.108.126.2
!
interface bri 0
ip address 10.108.126.1 255.255.255.0
dialer-group 1
dialer map ip 10.108.126.2 name B 5551234
!
dialer idle-timeout 300
Access list defininginteresting packetson Cisco A
Static routes to
reach destination
Interfaceconfiguration forDDR
Time to wait
before droppingcall
Legacy DDR Using ACLsConfiguration Example
Subnets192.168.12.0192.168.14.0
10.108.126.1 10.108.126.2
ISDNA B
Verifying Legacy DDR and
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Router#ping or telnet
Router#show dialer
Router#show isdn active
Router#show isdn status
Triggers a link (assuming it is partof interesting traffic)
Displays current status of link, includingamount of time link is connected
When using ISDN, displays callstatus while call is in progress
Displays the status of an ISDNconnection
Router#show ip route Displays all routes, including static
routes
Verifying Legacy DDR andISDN Operation
Verifying Legacy DDR and
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Router#debug dialer Shows call setup and teardown
activity
Clears currently establishedconnections from the interface
Router#debug isdn q921 Shows ISDN layer 2 messages
Router(config-if)#shutdown
Verifying Legacy DDR andISDN Operation (cont.)
Shows ISDN call setup andteardown activityRouter#debug isdn q931
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Review Questions
1. Differentiate between a native and anonnative ISDN BRI interface.
2. How do you configure a Cisco router to
interface to an ISDN switch? Why do youneed to be specific about the switch type?
3. List and describe the three tasks associated
with configuring DDR.4. Why might you choose to use an access list
to define interesting traffic for DDR?