Dual SIM Failover
Introduction
Overview
The Westermo MRD-455 is a compact, DIN rail mountable dual SIM mobile 4G router. The dual
SIM failover feature has been developed for 2 main reasons.
The first being for mobile applications, where the router is installed in vehicles, boats, trains etc
and likely to be moving between strong and weak areas of coverage by different mobile
providers.
The second for mission critical applications where the remote network may be static, but the
customer needs resilience against a failure with the mobile network. Wireless WAN
technologies such as GPRS, 3G And 4G have proven to be extremely reliable. But because
cellular routers tend to be placed in remote and difficult to reach places, (and outside the reach
of wired networks), it warrants extra precautions. Especially when the consequences of losing
contact with a remote network can be severe in terms of recovery costs and site visits.
This application note describes a basic and advanced method of SIM to SIM failover. The
advanced method configures the router to actively monitor the 4G link to test its ability to route
traffic. It then drops the link and goes into recovery/failover mode if it detects a problem.
The router initially tries to recover the link on the same SIM card before failing over to the second
SIM card after a specified number of retries.
Overview
This application note applies to the MRD 4G & 3G router range and assumes you are starting from
a factory default configuration.
Corrections
Requests for corrections or amendments to this application note are welcome and should be
addressed technical@westermo.co.uk
Requests for new application notes can be sent to the same address.
