Intermittent connectivity loss with em(4)

James B. Byrne byrnejb at
Thu Oct 10 14:00:51 UTC 2019

On Tue, October 8, 2019 09:07, Sergio de Almeida Lenzi wrote:
> Em ter, 2019-10-08 às 10:51 +0200, Morgan Wesström escreveu:
>> That is almost correct. The cable modem is a SagemCom 2864 with
>> tailored
>> firmware for my ISP and it has a setting to switch between
>> NAT/bridge
>> mode. I've put it in bridge mode and the ISP provides 4 public
>> IP-addresses through DHCP.
> Hello... in Brazil   I solved the problem when I put a small 5 port
> switch between the modem and  the FreeBSD machine..
> one cable FreeBSD  -> small switch ->  modem  instead of : Freebsd ->
> modem
> since than no connection drop at all
> I do not know why this happens.. must be something about hardware,
> timing...

It the host with the problem has an Intel Atom mainboard then the BIOS
might be set to power off the NIC chip if there is no traffic on the
port for an extended period.  The hub might be generating enough
heartbeat traffic to keep the timeout from happening while the cable
modem does not.

We had this happen with some of our gateways built on Atom board
systems. The BIOS was factory set to use this feature as a
power-saving device on laptops.

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James B. Byrne                mailto:ByrneJB at
Harte & Lyne Limited
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