Both the CTM-ONE and CTM-500 wireless gateway support dual SIMs, allowing for two active SIMs from different carriers to be installed. This enables failover functionality, where if one SIM fails to provide the required connectivity, the modem automatically switches to the alternate SIM.
Pre-requisite:
Firmware version 1.5.4 or later.
Ping failover operates by establishing communication with specific IP addresses or URLs designated as ICMP ping targets to assess network connectivity. This failover mechanism does not consider cellular parameters like signal strength; instead, it depends on the modem's ability to successfully or unsuccessfully communicate with a predefined server via ping.
Configuration Keywords | Definition |
|---|---|
Primary SIM |
|
Primary Ping Target | The ping target of the primary SIM. |
Secondary SIM |
|
Secondary Ping Target | The ping target of the secondary SIM. |
Failback Target URL | The ping target of the primary SIM to switch back from the secondary SIM. |
Primary IoT URL | Cypress-IOT URL used when on primary SIM1. |
Secondary IoT URL | Cypress-IOT URL used when on secondary SIM2. |
Maxed Failed Attempts | Number of failed ping attempts before the SIM switches. |
Ping Check Period | Sleep duration in minutes between each ping attempt. |
Maximum Cell Offline Time | If the maximum time is reached while a device is offline, the device will reset to attempt to establish a new connection. |
How does it work?
For failover to work, the modem requires two ping "targets," one on each SIM/carrier installed. A ping target is an IP or URL that the modem uses to determine the "health" of the connection. If pinging the target fails, the modem failover mechanism will activate and move to the alternate SIM.
Each SIM requires a valid pingable target to determine the state of the wireless connection. The success or failure of the pings determines when or if the modem switches to the secondary SIM. Additionally, a "Failback" feature allows the modem to switch back to the primary SIM when the connection becomes available again. This feature is useful if a specific carrier is preferred. In such cases, the preferred carrier SIM should be installed in SIM slot 1.
Set primary (SIM slot 1) and secondary (SIM slot 2) ping targets
Each SIM can have up to 3 ping target URL/addresses.
On the CTM device, under Configuration navigate to: network > monitoring > network watchdog.
Enable SIM failover (no Failback)
If the “Enable SIM failover” checkbox is enabled and “Enable SIM failback” is UNCHECKED, this is the workflow:
Primary SIM (SIM1) registers and connects if available.
The primary ping target will be pinged at the time interval set by the user in "Primary ping target".
The modem will continue to ping the SIM1 target and will remain on the primary SIM (SIM1).
If pings to the primary (SIM1) target are unsuccessful, the modem will switch to the secondary SIM (SIM2).
The secondary SIM (SIM2) will ping the "Secondary ping target" while on SIM2. If successful, it will remain on SIM 2 and continue pinging the secondary target from the secondary SIM (device will stay using SIM 2).
If the SIM2 (secondary) PING URL is not reachable from SIM 2, it will switch back to SIM 1 after the specified ping interval and then return to step 1.
Enable SIM Failover (With Failback)
If “Enable SIM failover” and “Enable SIM failback” checkboxes are CHECKED, this is the workflow:
The primary SIM (SIM1) attempts to register and connect if available.
The primary ping target is pinged at the time interval set by the user in "Primary ping target".
The modem continuously pings the SIM1 target and remains on the primary SIM (SIM1).
If pings to the primary (SIM1) target fail, the modem switches to the secondary SIM (SIM2).
While on the secondary SIM (SIM2), the modem pings the "Secondary Ping Target". If successful, it remains on SIM 2 and continues pinging the secondary target from the secondary SIM (Device stays using SIM 2).
While connected to the secondary SIM (SIM2), the modem attempts to ping the primary (SIM1) ping target. If the primary (SIM1) ping target continues to fail, the modem remains on the secondary (SIM2). If the primary (SIM1) ping target is available, the modem switches to the primary (SIM1) connection.
If the SIM2 (secondary) PING URL is not reachable from SIM 2 and the primary (SIM1) connection is not available, the modem switches back to SIM 1 after the specified ping interval and returns to step 1.
Cypress IOT URL for Failover
In certain private network configurations, devices may need an alternative URL to access Cypress IOT. In such instances, alternate URLs can be set up for device management and monitoring through Cypress IOT. Please refer to the details below:
