How much cellular bandwidth does my OOB network need?

Customers looking to deploy a cellular out-of-band network must consider bandwidth usage to properly estimate monthly carrier access charges.  Each application is unique, however there are some baseline measurements that can provide valuable information about bandwidth requirements.

If the network is designed for an “always on / call home” SSH tunnel to the Opengear Lighthouse appliance you will need to factor in SSH keep alive messages. SSH keep alive messages will consume anywhere from 3MB to 40MB per month depending on how you tune the frequency of the SSH keep alive intervals.  If the application is designed for minimal use during an occasional out-of-band management session users are likely to consume 35KB-100KB per session for a quick fix on a small config.

Here are some ballpark figures from a Cisco management session using an Opengear ACM5004-G where a Cisco device is rebooted, Auto-Response breaks into ROMmon, print some diagnostics, continues to  boot, watches boot messages, then shows running-config and disconnects.

“Upload” is from the perspective of billing, i.e. data outbound from the ACM. “Download” is data inbound to the ACM.

Protocol Upload / Download
Raw TCP 40KB / 35KB
Telnet 45KB / 40KB
SSH 75KB / 40KB
SSH compress* 70KB / 42KB
pmshell**  6KB / 100 bytes

* SSH with Compression=delayed on the server, about the same using default and CompressionLevel=9 on the client.

** No network baseline measurement.

The session was roughly 700 – 800 packets each way so less than 100 bytes per packet.

The amount of bandwidth required will vary depending on the type of installation. M2M plans with pooled data may be the right fit for some applications and prove too expensive for others.  With the flexibility of the Opengear devices you can tune with great precision the exact amount of bandwidth you wish to consume.  Included with the cellular out-of-band products is a bandwidth watchdog that will send elevated alerts to inform users if there is opportunity for a bandwidth overage.

Always available connectivity to remote network infrastructure is a key feature for Opengear out-of-band solutions.  Maintaining smart management access over a cellular out-of-band network is a cost-effective way to ensure 100% availability.