Overview

To ensure high availability of network connectivity for IoT devices, when the primary cellular network (SIM card) fails, the gateway can automatically switch to the backup cellular network. This guide will walk you through configuring the dual SIM cold backup failover function based on WWAN1 (primary link) and WWAN2 (backup link) in the "Link Management" interface of your Robustel gateway.

Hardware/Software Prerequisites

● 1x Robustel Gateway (e.g., Model R1520)

● 2x Activated SIM cards, correctly inserted into the gateway's WWAN1 and WWAN2 slots

● A computer with access to the gateway's Web Management Interface

● Administrator account (e.g., admin) privileges

Step-by-Step Configuration Guide

Step 1: Log in and Navigate to the Link Management Interface

1. Log in to the gateway's Web Management Interface using a browser.
2. In the left navigation bar, click successively on [Interface] -> [Link Management]. The "Link Management" and "Status" areas will be displayed on the right.

Step 2: Configure the Failover Policy

In the "Link Management" section, configure the following settings:

1. Primary Link: Select WWAN1 from the dropdown menu.
2. Backup Link: Select WWAN2 from the dropdown menu.
3. Backup Mode: Select Cold Backup. In this mode, the backup link (WWAN2) will only be activated when the primary link (WWAN1) fails.
4. Restoration Interval: Set to 10 minutes. This means the gateway will check every 10 minutes if the primary link has recovered; if so, it will automatically switch back.
5. Abnormal Restart: Keep this setting Disabled.

Refer to the configuration shown in the figure below:

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Step 3: Configure Ping Detection for Both Links

Link switching relies on the Ping detection settings configured for WWAN1 and WWAN2. This needs to be enabled and configured with an IP address that is reachable:

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Verification and Testing

1. Check Status: After submitting the configuration, go to the [Status] menu to view the currently active link and confirm that WWAN1 is the primary link.
2. Simulate Failure Test: Disconnect the WWAN1 antenna or remove the WWAN1 SIM card. Observe the gateway status; it should automatically switch the network connection to WWAN2 within a short time (depending on network detection time). The status page should then show WWAN2 as the active link.
3. Recovery Test: Reconnect the WWAN1 antenna or SIM card. Wait for about 10 minutes (the restoration interval we set) and observe if the gateway automatically switches back to WWAN1.

Troubleshooting / FAQ

Q1: After submitting the configuration, the failover function does not work and it cannot switch to the backup link?

A1: Please check the following steps:

● Check SIM Card Status: Confirm that the WWAN2 SIM card is correctly installed and that the carrier network service is normal.

● Check Signal Strength: In the [Cellular] menu, ensure WWAN2 has sufficient cellular network signal strength.

● Check if Ping Detection is Enabled: Verify that the Ping Detection function is enabled for both WWAN1 and WWAN2.

Q2: How should I configure the gateway if I want both the primary and backup links to be online simultaneously?

A2: Cold Backup mode is suitable for primary/backup switching scenarios. If you require both links to be active simultaneously, you need to use a dual-module product like the R2000DUAL and change the "Backup Mode" to "Hot Backup".

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