Complete hangup of network caused by single device

Hi all,

I'm being troubled by this most peculiar problem. In an embedded environment, the PC (running XP Embedded) sometimes falls into a complete hangup (i.e. XP doesn't respond to anything). It is related to a hangup of the network; the PC hardware involved seems to do something on its network connection that causes the switch (brand: SMC, 24 ports) to block all traffic to/from the other participants on the network. As soon as I disconnect the cable from the hanging PC the whole networks OK again.

I wonder, which phenomenon on a single Ethernet connection could cause that a complete network is locked out?

(the vendor already has had his own internal network locked out in an attempt to reproduce the issue, so he's sure the problem exists)

Any clues?

Rob Hulsebos Philips Netherlands

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RH wrote in part:

From your email addr, I presume you are not a Black Hat.

Any broadcast that occurs too frequently (flooding) will bring many ethernets to a crawl if not a stand-still. For many unmanaged switches, any unknown (non replying) MAC address qualifies as broadcast.

The real problem is why the device [re]transmits too frequently. Sounds like a buggy timer/timeout. Sometimes, a loop (redundant path) can cause the same troulbe.

-- Robert

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