Cellular data usage depends on how the cell modem is used and when and where it is active. OOB management is text-based (CLI/SSH) and uses very little data, typically 1MB/month for actual activity based usage. Here are some guidelines to help you choose an appropriate cellular plan based on usage:
- Lowest - The modem is in failover mode, which means that it stays off unless needed. Cellular data is only used for maintenance, site turn up, troubleshooting, and Lighthouse connection during outages.
- Low – The modem is on but using a NAT IP as a heartbeat. The Lighthouse VPN only uses the modem if there is an outage.
- Medium – The modem is on available on the Internet with a public static IP but the Lighthouse Callhome feature only uses the modem during outages. Accidental or malicious connection attempts will be declined, but you will be charged by the carrier for the declined packet traffic.
- High - The largest consumer of data is the Lighthouse Callhome tunnel, which is VPN-based. The VPN may use IPsec Dead Peer Detection and OpenVPN ping/keepalives, increasing usage. Leaving the cell modem up at all times and using the Callhome tunnel rather than the production LAN may result in up to 200MB/month of usage. This scenario is rare, but could occur if your only path to the site device is via the cell modem.
As per the article on choosing a cellular plan, we advise monitoring your cellular usage to account for your network and unique usage patterns. This article provides general guidance but is not a substitute for real world testing.
Points of note:
- Cellular carriers typically charge for both inbound and outbound network traffic, so the numbers in this article are for combined inbound and outbound usage and are given in megabytes (MB).
- If your Opengear device has a public cellular IP, even when an access attempt is blocked by the Opengear device's firewall, the inbound data used still counts against your quota. Nevertheless, enabling security features such as Brute Force Protection can discourage attack attempts (i.e. the perpetrator moves on in search of an "easy target") that would otherwise use data.
- Always configure cellular data usage alerts to avoid overage charges.
Refer to this article for details on available failover modes.