RV50 modem TCP keep-alive

AirLink Routers
1

We have 100+ RV50 modems communicating over Verizon cellular.
If one of the modems is offline (due to poor signal) and is polled for data by the main device using TCP, when it comes back online it will continuously close the TCP connection our main device is trying to create.

Wireshark
Wireshark1295×480 327 KB

The RV50 modem will do this until the Serial Watchdog timer reboots the modem.
We are on the latest firmware.

Any help on how to stop the modem from repeatedly closing the TCP connection or a TCP keep-alive setting of some sort would be appreciated.

2

Hi @tjones,

Please refer to the following ideas:

Are you using the latest firmware? If not, please download and install from the following link: https://source.sierrawireless.com/resources/airlink/software_downloads/rv50/rv50-firmware-list/#sthash.8lC1rldO.dpbs

As you describe, do you need the TCP Persistent Connection feature?

tcp persistent connection
tcp persistent connection1027×264 64.5 KB

Please refer to Table 11-2: RS232 Configuration > PAD under TCP Persistent Connection on page 313 of the following document: https://source.sierrawireless.com/resources/airlink/software_reference_docs/airlink-rv-series---configuration-guide/#sthash.Y7ZDQOAA.dpbs

After you enable that feature, please give me screenshots of your configurations.

Thanks,

3

Thanks for the suggestions.
We have figured out our problem.
We had the Destination Address (under Serial → PAD) set to our main RTU.

In the RV50 modem log, the modem was establishing a TCP connection to this Destination Address when it booted up.

Then the modem would not allow the RTU to poll it, because the RTU was trying to establish a different TCP connection.

When the connection that the modem had established to the RTU was closed somehow, then correct communications would start from the RTU polling the modem.

If we clear out the Destination Address setting, everything appears to work good.