Backup methods between 3G and ADSL

Latest reply: Jan 29, 2016 23:06:51 3369 3 0 0

As devices tend to support more and more technologies the need to setup multiple WAN connections and redundancy between them arises. To better exemplify this kind of scenario I have set up a AR169FGVW-L running system software version V200R005C20 as a CPE that has an active ADSL and 3G connection.

The goal is to have only one active data link (the ADSL link is preferred because of the considerably higher data rates available) and the other WAN link as backup.

In the topology below I am using the AR169FGVW-L as a CPE and a S5700-EI as a LAN switch. All the LAN users are connecting to the internet via the AR169 and need uninterrupted connections regardless of the state of the network. To make sure we can fulfill this requirement I will demonstrate how to setup redundancy between the ADSL and the 3G link.

Backup methods between 3G and ADSL-1333137-1

The configuration of the 2 interfaces are listed below:

#ADSL config#

interface Virtual-Template1

 ppp chap user user1

 ppp chap password cipher %@%@^'4d6W9"x@{.Lk>HKmY#,*9S%@%@

 ip address ppp-negotiate


interface Atm0/0/0


interface Atm0/0/0.3

pvc 0/50

  service vbr-nrt 500 500 1

  map ppp Virtual-Template1


interface Cellular0/0/0

dialer enable-circular

 dialer-group 1

 dialer timer idle 30

 apn-profile 3G

 dialer timer autodial 10

 dialer number *99#

 ip address negotiate


apn profile 3G

 user name user1 password cipher %@%@7VIL=,H!'NQY=nP1dT6M,I78%@%@ authentication-mode chap

 apn 3G.apn

#Static routes#

ip route-static Cellular0/0/0

ip route-static Virtual-Template1


There are 2 possible solution for this requirement:


1.       The first one is a Huawei proprietary feature called “Interface Backup”. Interface Backup is a

very efficient way to setup redundancy as the switchover time is 5s compared to a floating route where the switchover will take about 30s.

To enable Interface backup you only need to run one command on the interface that will be the backup, in this case the 3G interface.


interface Cellular0/0/0

 standby interface Atm0/0/0



Once this command is applied the Cellular interface will change to “Administratively down” state and the active link will be the ADSL. You can view the interface backup state by running the command below:
[AR169] display standby state

Interface                  Interfacestate Backupstate Backupflag Pri   Loadstate

ATM0/0/0                               UP            MUP              MU

Cellular0/0/0                     STANDBY     STANDBY      BU          0


 Backup-flag meaning:

 M---MAIN  B---BACKUP     V---MOVED    U---USED




2.       The second solution I would like to present is the configuration of a Floating Route. This means

that the static routes already configured will need to be modified as the route through the Virtual-template interface needs to have a lower preference (preferred route).

The configuration is listed below:

#Static routes#

ip route-static Cellular0/0/0

ip route-static Virtual-Template1 preference 30



The default preference for static routes is “60” so in this case, because both routes have the same destination, only the route through the Virtual-Template interface will be added to the routing table. The other one, through the 3G interface, will remain as a backup and will only be added to the routing table if the ATM interface fails.

This method is sometimes preferred by network designers because is does not involve proprietary protocols and it has no restriction with regards to device vendors. On the other hand, Interface Backup is a much more efficient method with regards to the detection and switchover time. The total switchover time is of 5s  compared to a floating route that will take 30s to switchover between active and standby interfaces.

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Created Sep 1, 2014 01:01:24 Helpful(0) Helpful(0)

Thanks a lot.
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Created Oct 30, 2015 10:26:18 Helpful(0) Helpful(0)

Try using "Cloudbacko Pro" software as it provides On site and Off site backup solution and FREE of charge for backing up ESXi Free version. So leaving a link just check:

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Created Jan 29, 2016 23:06:51 Helpful(0) Helpful(0)

This is very nice and cool post tahsnk for this ..........!!!!!!!!!!!!!!!!!!!!!!!!

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