[Gllug] OT: What can take out a switch *and* an ethernet card?

Ian Northeast ian at house-from-hell.demon.co.uk
Thu Sep 30 21:40:27 UTC 2004


Not really about Linux but I think the good folks on here are probably 
the best bet.

I came home tonight to discover I had no network. My cheapo no-name 
bought from Scan for 60 quid 2 years ago 16 port switch was dead - 
lights flashing at random, powering off and on again just resulted in 
different (wrong) lights flashing. Definitely no traffic through it.

OK, so I didn't expect it to last a lifetime so I broke out the 
emergency backup 8 port 10Mb hub and plugged the important machines into 
it. Most stuff came back OK - I had to reboot the Suns which surprised 
me but perhaps I just don't know enough about Solaris, but that's not 
relevant.

The one thing which didn't come back was my workstation, which is an 
oldish home built job with a P500 from when a P500 was state of the art, 
with an RTL8193, running Debian Woody. I'd been meaning to replace this 
card with an Intel one for some time, but never got round to it because 
it's never given any trouble in the past. It used to work with the hub, 
but the machine was running - I think - Red Hat 5.2 back then. The 
symptom was that it would receive OK, but its transmissions were not 
seen by the rest of the network. Mii-tool reported the link down, but a 
successful negotiation of 10-hd, which happened quickly, accompanied by 
a "based on partner ability" message - so I don't think it can have been 
a timeout due to lack of response. Link lights were on both ends. 
Tcpdump showed packets flying around, including me being pounded with 
arp requests and replying to them, but the replies never showed at the 
other end. A verified good cable didn't help. So I whipped out the 
RTL8139 and put the Intel card in and up it all came.

So it appears that something took the switch *and* my ethernet card out 
at the same time. But nothing else. I didn't think it was possible for 
ethernet devices to take each other out. It's all low voltage isn't it?

Can anyone explain this? Also, can anyone recommend the best place 
nowadays to get another 16 port 10/100 (I have a number of 10Mb devices 
which matter, like my firewall and my printer) switch?

Regards, Ian


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