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Chapter 13      Configuring Dial Backup and Remote Management
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!dsl operating-mode auto
!
! Dial backup interface, associated with physical BRI0 interface. ! Dialer pool 1 associates it with BRI0’s dialer pool member 1. 
! Note “dialer watch-group 1” associates a watch list with corresponding 
! “dialer watch-list” command.interface Dialer0
 ip address negotiated
 encapsulation ppp dialer pool 1
 dialer idle-timeout 30
 dialer string 384040 dialer watch-group 1
 dialer-group 1
!! Primary interface associated with physical ATM0 interface. 
! Dialer pool 2 associates it with ATM0’s dial-pool-number2.
interface Dialer2 ip address negotiated
 ip mtu 1492
 encapsulation ppp dialer pool 2
 dialer-group 2
 no cdp enable
!ip classless
!
! Primary and backup interface are given route metric.ip route 0.0.0.0 0.0.0.0 22.0.0.2
ip route 0.0.0.0 0.0.0.0 192.168.2.2 80
ip http server!
! Watch for interesting traffic.
dialer watch-list 1 ip 22.0.0.2 255.255.255.255
! Specifies interesting traffic to trigger backup ISDN traffic.
dialer-list 1 protocol ip permit!
Configuring Dial Backup and Remote Management Through the 
Console or Auxiliary Port
When customer premises equipment, such as a Cisco 850 or Cisco 870 series router is connected to an 
ISP, an IP address is dynamically assigned to the router, or the IP address may be assigned by the router 
peer through the centrally managed function. The dial backup feature can be added to provide a failover 
route in case the primary line fails. Cisco 850 and Cisco 870 routers can use the auxiliary port for dial 
backup and remote management.
NoteThe cable modem environment is currently not supported. 
						

							
 
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Chapter 13      Configuring Dial Backup and Remote Management
  Configuring Dial Backup and Remote Management Through the Console or Auxiliary Port
Figure 13-1  shows the network configuration used for remote management access and for providing 
backup to the primary WAN line.
Figure 13-1 Dial Backup and Remote Manage ment Through the Auxiliary Port
82269
A1
3
2
2
C
B
BC
2
AT M
PSTN
1Cisco 850 or Cisco 870 
series routerAMain WAN link; primary connection to Internet service provider
2ModemBDial backup; serves as a failover link for Cisco 870 routers when 
primary line goes down
3PCCRemote management; serves as dial-in access to allow changes or 
updates to Cisco IOS configurations
Configuration Tasks
Perform these steps to configure dial backup and re mote management for these routers, beginning in 
global configuration mode:
CommandPurpose
Step 1ip name-server  server-address
Example:
Router(config)#  ip name-server 
192.168.28.12
Router(config)#
Enters your ISP DNS IP address.
Ti pYou may add multiple server addresses if 
available.
Step 2ip dhcp pool  name
Example:
Router(config)#  ip dhcp pool 1
Router(config-dhcp)#
Creates a DHCP address pool on the router and 
enters DHCP pool configuration mode. The  name 
argument can be a string or an integer.
 Configure the DHCP address pool. For 
sample commands you can use in DHCP pool 
configuration mode, see the 
“Configuration 
Example” section on page 13-13. 
						

							 
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Step 3exit
Example:
Router(config-dhcp)# exitRouter(config)#
Enters global configuration mode.
Step 4chat-script script-name expect-send
Example:
Router(config)# chat-script Dialout ABORT 
ERROR ABORT BUSY ““ “AT” OK “ATDT 5555102 
T” TIMEOUT 45 CONNECT \c
Router(config)#
Configures a chat script used in dial-on-demand 
routing (DDR) to give commands to dial a modem 
and to log in to remote systems. The defined script 
is used to place a call over a modem.
Step 5interface type number
Example:
Router(config)# interface Async 1Router(config-if)#
Creates and enters configuration mode for the 
asynchronous interface.
 Configure the asynchronous interface. For 
sample commands you can use in async 
interface configuration mode, see the 
“Configuration Example” section on 
page 13-13.
Step 6exit
Example:
Router(config-if)# exit
Router(config)#
Enters global configuration mode.
Step 7interface type number
Example:
Router(config)# interface Dialer 3Router(config-if)#
Enters interface configuration mode.
Step 8dialer watch-group group-number
Example:
Router(config-if)# dialer watch-group 1
Router(config-if)#
Specifies the group number for watch list.
Step 9exit
Example:
Router(config-if)# exit
Router(config)#
Enters global configuration mode.
Command Purpose 
						

							 
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Step 10ip nat inside source {list access-list-number} 
{interface type number | pool name} [overload]
Example:
Router(config)# ip nat inside source list 
101 interface Dialer 3 overload
Enables dynamic translation of addresses on the 
inside interface.
Step 11ip route prefix mask {ip-address | interface-type 
interface-number [ip-address]}
Example:
Router(config)# ip route 0.0.0.0 0.0.0.0 
22.0.0.2
Router(config)#
Sets the IP route to point to the dialer interface as 
a default gateway.
Step 12access-list access-list-number {deny | permit} 
source [source-wildcard]
Example:
Router(config)# access-list 1 permit 
192.168.0.0 0.0.255.255 any
Defines an extended access list that indicates 
which addresses need translation.
Step 13dialerwatch-list group-number {ip ip-address 
address-mask | delay route-check initial 
seconds}
Example:
Router(config)# dialer watch-list 1 ip 
22.0.0.2 255.255.255.255
Router(config)#
Evaluates the status of the primary link, based on 
the existence of routes to the peer. 22.0.0.2 is the 
peer IP address of the ISP.
Step 14line [aux | console | tty | vty] line-number 
[ending-line-number]
Example:
Router(config)# line console 0Router(config-line)#
Enters configuration mode for the line interface.
Step 15modem enable
Example:
Router(config-line)# modem enable
Router(config-line)#
Switches the port from console to auxiliary port 
function.
Step 16exit
Example:
Router(config-line)# exit
Router(config)#
Enters global configuration mode.
Command Purpose 
						

							 
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Chapter 13      Configuring Dial Backup and Remote Management
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Configuration Example
The following configuration example specifies an IP address for the ATM interface through PPP/IPCP 
address negotiation and dial backup over the console port.
!
ip name-server 192.168.28.12ip dhcp excluded-address 192.168.1.1
!
ip dhcp pool 1 import all
 network 192.168.1.0 255.255.255.0
 default-router 192.168.1.1!
! Need to use your own correct ISP phone number.
modemcap entry MY-USER_MODEM:MSC=&F1S0=1chat-script Dialout ABORT ERROR ABORT BUSY ““ “AT” OK “ATDT 5555102\T”
TIMEOUT 45 CONNECT \c
!!
!
!interface vlan 1
 ip address 192.168.1.1 255.255.255.0
 ip nat inside ip tcp adjust-mss 1452
 hold-queue 100 out
!! Dial backup and remote management physical interface.
interface Async1
 no ip address encapsulation ppp
 dialer in-band
 dialer pool-member 3 async default routing
 async dynamic routing
 async mode dedicated ppp authentication pap callin
!
Step 17line [aux | console | tty | vty] line-number 
[ending-line-number]
Example:
Router(config)# line aux 0Router(config)#
Enters configuration mode for the auxiliary 
interface.
Step 18flowcontrol {none | software [lock] [in | out] | 
hardware [in | out]} 
Example:
Router(config)# flowcontrol hardware
Router(config)#
Enables hardware signal flow control.
Command Purpose 
						

							 
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Chapter 13      Configuring Dial Backup and Remote Management
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interface ATM0 mtu 1492
 no ip address
 no atm ilmi-keepalive pvc 0/35
 pppoe-client dial-pool-number 1
!dsl operating-mode auto
!
! Primary WAN link.interface Dialer1
 ip address negotiated
 ip nat outside encapsulation ppp
 dialer pool 1
 ppp authentication pap callin ppp pap sent-username account password 7 pass
 ppp ipcp dns request
 ppp ipcp wins request ppp ipcp mask request
!
! Dialer backup logical interface.interface Dialer3
 ip address negotiated
 ip nat outside
 encapsulation ppp no ip route-cache
 no ip mroute-cache
 dialer pool 3 dialer idle-timeout 60
 dialer string 5555102 modem-script Dialout
 dialer watch-group 1!
! Remote management PC IP address.
peer default ip address 192.168.2.2no cdp enable
!
! Need to use your own ISP account and password.ppp pap sent-username account password 7 pass
ppp ipcp dns request
ppp ipcp wins requestppp ipcp mask request
!
! IP NAT over Dialer interface using route-map.ip nat inside source route-map main interface Dialer1 overload
ip nat inside source route-map secondary interface Dialer3 overload
ip classless!
! When primary link is up again, distance 50 will override 80 if dial backup 
! has not timed out. Use multiple routes because peer IP addresses are alternated ! among them when the CPE is connected.
ip route 0.0.0.0 0.0.0.0 64.161.31.254 50
ip route 0.0.0.0 0.0.0.0 66.125.91.254 50ip route 0.0.0.0 0.0.0.0 64.174.91.254 50
ip route 0.0.0.0 0.0.0.0 63.203.35.136 80
ip route 0.0.0.0 0.0.0.0 63.203.35.137 80ip route 0.0.0.0 0.0.0.0 63.203.35.138 80
ip route 0.0.0.0 0.0.0.0 63.203.35.139 80
ip route 0.0.0.0 0.0.0.0 63.203.35.140 80ip route 0.0.0.0 0.0.0.0 63.203.35.141 80
ip route 0.0.0.0 0.0.0.0 Dialer1 150
no ip http serverip pim bidir-enable
! 
						

							 
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! PC IP address behind CPE.access-list 101 permit ip 192.168.0.0 0.0.255.255 any
access-list 103 permit ip 192.168.0.0 0.0.255.255 any
!! Watch multiple IP addresses because peers are alternated 
! among them when the CPE is connected.
dialer watch-list 1 ip 64.161.31.254 255.255.255.255dialer watch-list 1 ip 64.174.91.254 255.255.255.255
dialer watch-list 1 ip 64.125.91.254 255.255.255.255
!! Dial backup will kick in if primary link is not available 
! 5 minutes after CPE starts up.
dialer watch-list 1 delay route-check initial 300dialer-list 1 protocol ip permit
!
! Direct traffic to an interface only if the dialer is assigned an IP address.route-map main permit 10
 match ip address 101
 match interface Dialer1!
route-map secondary permit 10
 match ip address 103 match interface Dialer3
!
! Change console to aux function.
line con 0 exec-timedout 0 0
 modem enable
 stopbits 1line aux 0
 exec-timeout 0 0
 ! To enable and communicate with the external modem properly. script dialer Dialout
 modem InOut
 modem autoconfigure discovery transport input all 
 stopbits 1
 speed 115200 flowcontrol hardware
line vty 0 4
 exec-timeout 0 0 password cisco
 login
!scheduler max-task-time 5000
end 
						

							
 
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Chapter 13      Configuring Dial Backup and Remote Management
  Configuring Dial Backup and Remote Management Through the ISDN S/T Port
Configuring Dial Backup and Remote Management Through the 
ISDN S/T Port
Cisco 876 and Cisco 878 routers can use the ISDN S/T  port for remote management. With an advanced 
enterprise (c870-adventerprisek9-mz) image, a Cisco  876 router can also use the ISDN S/T port for 
dial
 backup.
Figure 13-2  and  Figure 13-3 show two typical network configurations used to provide remote 
management access and backup for the primary WAN line. In Figure 13-2, the dial backup link goes 
through a customer premises equi pment (CPE) splitter, a digital subscriber line access multiplexer 
(DSLAM), and a central office (CO) splitter  before connecting to the ISDN switch. In 
Figure 13-3, the 
dial backup link goes dire ctly from the Cisco router to the ISDN switch.
Figure 13-2 Dial Backup Through CPE Spli tter, DSLAM, and CO Splitter
82892
AT M
network
Internet
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23
4
87
6
5
C
A
1
1Cisco 876 or Cisco 878 routerAPrimary DSL interface
2DSLAMBDial backup and remote management through the 
ISDN interface (ISDN S/T port); serves as a 
failover link when the primary line goes down
3ATM aggregator
4ISDN switch
5ISDNCAdministrator remote ma nagement through the 
ISDN interface when the primary DSL link is 
down; serves as dial-in access to allow changes or 
updates to Cisco IOS configuration
6ISDN peer router
7We b  s e r v e r
8Administrator—— 
						

							
 
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Chapter 13      Configuring Dial Backup and Remote Management   Configuring Dial Backup and Remote Management Through the ISDN S/T Port
Figure 13-3 Dial Backup Directly from Router to ISDN Switch
88208
AT M
network
Internet
B
5
4
3
76
C
A
12
1PCAPrimary DSL interface
2Cisco 876 routerBDial backup and remote management through the ISDN 
interface (ISDN S/T port); serves as a failover link when the 
primary line goes
 down3DSLAM
4Aggregator
5ISDN switchCAdministrator remote manageme nt through the ISDN interface 
when the primary DSL link is down; serves as dial-in access to 
allow changes or updates to Cisco IOS configuration
6We b  s e r v e r
7Administrator
Configuration Tasks
Perform the following tasks to configure dial backup and remote management through the ISDN S/T port 
of your router:
 Configure ISDN Settings
 Configure the Aggregator and ISDN Peer Router
Configure ISDN Settings
NoteTraffic of interest must be present to activate the  backup ISDN line by means of the backup interface and 
floating static routes methods. Traffic of interest is  not needed for the dialer watch to activate the backup 
ISDN line. 
						

							 
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Chapter 13      Configuring Dial Backup and Remote Management
  Configuring Dial Backup and Remote Management Through the ISDN S/T Port
Perform these steps to configure your router ISDN interface for use as a backup interface, beginning in 
global configuration mode:
CommandPurpose
Step 1isdn switch-type switch-type
Example:
Router(config)# isdn switch-type basic-net3
Router(config)#
Specifies the ISDN switch type.
The example specifies a switch type used in 
Australia, Europe, and the United Kingdom. For 
details on other switch types supported, see the 
Cisco IOS Dial Technologies Command 
Reference.
Step 2interface type number
Example:
Router(config)# interface bri 0
Router(config-if)#
Enters configuration mode for the ISDN Basic 
Rate Interface (BRI). 
Step 3encapsulation encapsulation-type
Example:
Router(config-if)# encapsulation ppp
Router(config-if)#
Sets the BRI0 interface encapsulation type.
Step 4dialer pool-member number
Example:
Router(config-if)# dialer pool-member 1
Router(config-if)#
Specifies the dialer pool membership.
Step 5isdn switch-type switch-type
Example:
Router(config-if)# isdn switch-type 
basic-net3
Router(config-if)#
Specifies the ISDN switch type.
Step 6exit
Example:
Router(config-if)# exitRouter(config)#
Enters global configuration mode.
Step 7interface dialer dialer-rotary-group-number
Example:
Router(config)# interface dialer 0
Router(config-if)#
Creates a dialer interface (numbered 0–255) and 
enters interface configuration mode.