Wednesday, January 15, 2020

Printers lose link to switch when in power save mode - switch incapable of 10 M half duplex, how do you tackle that?

Hi!

Since the introduction of switches lacking the capability of half duplex (Extreme Networks X450-G2 for instance), we see that printers (and probably other stuff) lose the Ethernet link when the printer enters power save mode. This means that a printer cannot be managed and no status can be read from it during the power save mode. Looking back in the logs, we see that those same printers “flapped” between 1 G full duplex (FD) and 10 M HD when connected to old (10 M HD capable) X450e switches. With the X450-G2’s, they instead alternate between 1 G FD and no link. I think it’s safe to say that this is because the printer only advertises 10 M HD on the Ethernet link auto negotiation when it is in power save mode and the switch cannot accept that, so the link is brought down.

One fix is to set the power save mode of the printer to a less aggressive setting, but that raises the sleep power from 0.9 W to 36 W (Canon IR-Adv). Putting a small consumer switch between the printer and switch (with a power draw of ~5 W) also solves the problem, but adds to maintenance and cost.

More and more switches come out in multi-rate versions capable of 2.5 and/or 5 Gbps on the switch ports, dropping the support for 10 Mbps. This will also cause problems with power save gear that goes to 10 M HD (but is not the case here).

Does anyone else have this problem? Any info on how printer manufacturers tackle this problem?

/Fredrik



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