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upstart writes:

Routing 4G cellular data to a BSD network using bridge mode on the RUT-240:

The RUT-240 from Teltonika networks is a small and fairly inexpensive 4G router which is commonly used to provide internet connectivity for remote devices that are either in locations without regular fixed-line broadband, or where high availability is required. Think smart meters, monitoring systems, and so on.

In the case of high availability, the RUT-240 is connected in line with a conventional internet router, and it's own cellular connection is only used when a lack of connectivity is detected. Both of these configurations often involve the use of a special SIM card, to which the cellular operator has provisioned a static, public IP address, thus allowing inbound connections to the connected remote devices, (as well as access to the router itself for configuration and admin purposes).

[...T]oday we're going to use our RUT-240 for a completely different purpose. No special SIM required, and we're not going to be travelling out in to the wilds either. Just a regular pre-paid SIM, and the normal office surroundings.

Instead, we'll be exploring the use of this router as a backup connection for an existing OpenBSD-based router, or even - within limits - as a replacement for fixed line broadband. This latter option might make sense on a short term basis in a new office that hasn't been fully connected yet, or in a temporary office in an awkward location where DSL or fibre isn't available. Attending a conference, but all the decent hotels are fully booked? Stuck on a boat in dry dock? Not a problem!

Of course, for the main intended purpose, 100baseT isn't exactly a limitation here. Typical uses of the RUT-240 involve connecting it to an existing wired internet connection via the WAN socket and passing that through to another device connected to the LAN side, with the possibility of routing traffic via 4G LTE if the wired WAN connectivity fails. In these cases, even if the connection between the existing devices was syncing at 1000baseT, (or beyond), then unless our actual internet connection can provide bandwidth in excess of 100 mbit then we don't really lose anything in terms of raw speed. Technically, latency might be worse, but the difference will be so small as to be lost in the noise compared to the extra latency created by the packet processing of the RUT-240.

An interesting hardware project - anybody fancy trying it with Windows or Linux? [JR]

Original Submission