Jan, - A test to do would be to configure the switch and your device in half-duplex. First send the traffic from switch to the device and see whether this causes the switch to break. Secondly, send the traffic from device to the switch and see whether that causes the problem. Atleast, this way you would know, whether its your device or switch. Its also possible that you may not see the issue at all in half-duplex mode. You may not be able to do the test if switch is unmanaged. - Is the problem speed dependent i.e. does it happen both at 10Mbps and 100Mbps? - What kind of switch (model/manufacturer) are you using - there are quite few low cost switches available which are very marginal in meeting ESD requirements and are poor designs. Try using a switch from a different vendor. - You would need to get a *broken* switch in-house and do all basic debugging to figure out the problem. If its a hard damage, one of the exotic reasons could be CESD - Cable-sourced electro-static discharge (CESD) is a phenomenon that occurs when an electrically charged twisted pair RJ45 cable is plugged into network equipment such as a switch or NIC. CESD is characterized by higher current, longer discharge time than typical ESD events, and is caused by a variety of events. The electrical charge on the cable can build up from dragging a cable across a carpet during install or proximity to moving equipment (e.g. elevators), air ducts (moving air), or electrical equipment. The CESD tolerance of any given electronic system depends on many factors. It should be noted that carefully chosen isolation-magnetics, layouts and routings, and decouplings of the RJ45(s) and RJ45 associated circuit paths to the device, are all necessary to get the most protection against CESD. If CESD is the cause, I would suspect isolation transformer (magnetics) on the switch is burnt - you should be able to check for continuity on the transformer primary and secondary winding. However, if the port is alive (link up and can transmit/receive traffic) after reset or power recycling the switch, I would not suspect magnetics to be the cause of the problem. thanks, Ghazzali Majeed Broadcom Corp. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Jan Vercammen Sent: Thursday, August 01, 2002 7:04 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Ethernet switch burnout Hello SI-list, I have an urgent question concerning Ethernet twisted pair. We have received from the field three reports that one of our products seems to have the capability to physically damage the port of a switch to which it is connected. To be more specific: our device uses a Bob Smith termination. The RJ-45 unused pins are connected with 75ohm to a common-rail, which in turn is capcitively coupled (using 1nF) to the chassis (=housing of device), which is also connected to the logic ground of the PCB. The center taps of both transmit and receive are also connected with 50ohm to the same common rail. The other port is a switching hub and I do not know if shielded or unshielded cable was used. What seems to happen is that after a while the communication hangs and the port at the switch does not operate anymore, not with our device or any other. For now I cannot confirm that resetting the switch solves the problem and it looks that there is hard damage. I have heard of cable sheath discharges (the tubing of the cable charges and next discharges to the environment, damaging hardware). However, for now I would like to disregard such exotic scenario. So my questions are: -1- as anyone encountered similar switch burnouts (whether hard or soft)? -2- if so, what is the possible explanation and fix? Kind regards, Jan Vercammen Agfa-Gevaert, Belgium ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu