Alexander Harrowell wrote:
On Tuesday 07 April 2009 22:10:24 Charles Wyble wrote:
Been troubleshooting a very strange problem for a couple of weeks now.
I have a few hundred systems deployed throughout the United States utilizing EVDO connectivity with Verizon as a carrier. They are stationary.
Over the past few weeks clusters of them in SF and Lewisville TX and a few other areas have been failing intermittently. They are offline for several days, then online for a few days then go offline again. They are running Linux and PPPD.
Do they maintain a continuous data link in normal operation (like, say, connectivity for a LAN, or backhaul for a camera or some such), or do they request the data link when they need to send [whatever] (like a discrete SCADA system)? My (user only) experience is that cellular data service doesn't handle long sessions well.
I have a few Sprint EVDO cards. They go into standby when nothing is actively going on and fire up within seconds when there is something to do. I regularly use everything from SSH to streaming video without any issues. I only notice the delay with SSH when I don't type anything for a few minutes and it has to come active again, but I can leave it idle for hours and it never drops. As far as the OP goes, let them replace the cards if they think that's the problem. You and I may suspect something else is up, but if that's on their checklist, it is what it is. ~Seth