Setting Up a Cisco 3G Backup Solution

  1. Confirm that the cellular interface card has been installed with the relevant 3G simcard.
  2. Unlock the 3g simcard with the correct pin number. In below command 0000 is your pin number.
  3. cellular 0/0/0 gsm sim unlock 0000

  4. Create the cellular gsm profile. The username and password is what you authenticate too. In some instances it may be a service that the ISP provides or you may have your own service. Such as a RADIUS service.
  5. cellular 0/0/0 gsm profile create 1 chap password ipv4

  6. Create the chat script which will be used to establish connection with the ISP. “ATDT*98*1#” is what is used to connect to the ISP. You will need to contact your ISP to determine what code they use to allow connections. Also please be advised that “gsm” in the below line is allowed to be changed to any name you want.
  7. chat-script gsm "" "ATDT*98*1#" TIMEOUT 60 "CONNECT"

  8. Place following lines under the cellular 0/0/0 interface.
  9. interface cellular 0/0/0
    dialer string gsm
    dialer-group 1

  10. Following also needs to be placed under the cellular 0/0/0 interface. Please note that the username and password need to be the same as ppp chap profile created in step 3.

    interface cellular 0/0/0
    ppp chap hostname
    ppp chap password 0 bleh

  11. Create a default route pointing to the cellular interface. Of course if you wanted only certain network traffic to go through cellular interface you could change this statement.

    ip route cellular 0/0/0

  12. Create a standard access-list so that the dialer script will activate when any ip traffic is matched.

    dialer-list 1 protocol ip permit

  13. Associate the async line with the gsm dialer script.

    script dialer gsm

  14. The 3g should now be able to be tested. Remove your WAN connection and try to ping a known ip address in your WAN network.

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