Cisco AUX port for back door emergency link configuration

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Here is most of important configuration for emergency backdoor link thru AUX port. As a network support engineer, it would be number 1 configuration stuff need to memorize and use it all the time.

Once your client said my network is down, especially WAN link, what you can do in remote ?. Drive or flight ? Oh man you know how you feel.

Cisco devices provide AUX port to save your time and job position(?). Buyging cheap modem and set this one up. It would release a lot of worries and fears(?).

Let see check the below.

1. Buy modem(of cause external) and If you have old router, buy RS-232 cable(32pin to 9pin)

2. Have phone # to use this back door emergency line

3. Connnect cable between Modem and Cisco device

4. Configure Cisco device ( In this example, using Cisco 3660 router)

 

Line configuration

 

Cisco Router(config)# line aux 0
Cisco Router(config-line)# exec-timeout 0 0
Cisco Router(config-line)# modem InOut
Cisco Router(config-line)# modem autoconfigure type nextport
or modem autoconfiguration discovery <-– if not sure what kinds of modem connected.
Cisco Router(config-line)# transport input all <– allow all protocols, such as telnet, ssh and so on
Cisco Router(config-line)# speed 115200

 

Cisco Router#sh modemcap <– to see modem type allow
default
codex_3260
usr_courier
usr_sportster
hayes_optima
global_village
viva
telebit_t3000
microcom_hdms
microcom_server
nec_v34
nec_v110
nec_piafs
cisco_v110
microcom_mimic
mica
nextport
scm

R2#

 

Logical Interface configuration

– Find line # first

Cisco Router(config)# interface Async225
Cisco Router(config-if)# ip address 192.168.1.10 255.255.255.0
Cisco Router(config-if)# encapsulation ppp
Cisco Router(config-if)# dialer in-band
Cisco Router(config-if)# dialer idle-timeout 60
Cisco Router(config-if)# async mode interactive
Cisco Router(config-if)# peer default ip address 192.168.1.11
Cisco Router(config-if)# ppp authentication chap

or

 

Cisco Router(config)# interface Async225
Cisco Router(config-if)# ip address 192.168.1.10 255.255.255.0
Cisco Router(config-if)# encapsulation ppp
Cisco Router(config-if)# dialer in-band
Cisco Router(config-if)# dialer idle-timeout 60
Cisco Router(config-if)# async mode interactive
Cisco Router(config-if)# peer default ip address pool emergency
Cisco Router(config-if)# ppp authentication chap

Cisco Router(config)# ip local pool emergency 192.168.1.11 192.168.1.12