[Soekris] spontaneous reboot with large packet flows on net5501+lan1741

Andrew Atrens andrew at atrens.ca
Tue Feb 17 19:37:51 CET 2015

Hi Nix,

It's almost certainly a power issue as power draw for the lan card will 
not be a static thing - ie will increase when transmitting packets vs idle.

Best case is that you have access to a DC-regulated power supply, 
perhaps one of these -


and can monitor the current draw as you bring up the board and test ..

If the setup is stable on this power source, you can watch how much 
current the 5501 is drawing and from that figure out how much punch 
you'll need in a static power source.

Good luck!


On 2015-02-17 12:25 PM, Nix wrote:
> So I just bought a lan1741 for my six-year-old net5501 (running the
> latest stable Linux kernel), because four ports just isn't *enough*.
> Unfortunately, it seems to not work entirely well.
> Enough packet flow over any ports on the lan1741 (not necessarily tiny
> packets either: a few thousand 1500-byte packets a second are enough)
> causes the net5501 to spontaneously reboot within a couple of minutes.
> The kernel never gets a look in, as far as I can see: the reset is
> immediate, nothing is logged, nothing is asserted.
> There is no such problem with the built-in ports (as long as the flow
> doesn't also involve a port on the lan1741), so my initial suspicion
> that the thing might be running out of power seems to be disproved. As
> it is, I have four ports on this machine that I can use only for things
> that might just about fill a 10MiB/s network or maybe even less (I
> haven't looked for the boundaries of this behaviour, though I might get
> out iperf and try). VoIP works on it, but anything heftier, like wifi,
> tends to cause reboots as soon as someone tries to, say, run a backup or
> do an apt-get or a pile of NFS traffic over that interface.
> So... has anyone seen this sort of thing before? Is this a known problem
> with the lan1741?

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