This was one of those "Twilight Zone" things.. I had configured a Linux box for a local reseller and had actually installed it at the ultimate client's site a month back. It was "networked" only in the sense that it had to talk to a network printer - it had no Internet connection at all.
Of course I configured it with a private IP to match the subnet that the printer was using, hooked it up and tested and all was good. All was good until the store manager showed me an old wy60 terminal at the front counter.. oops!
No serial ports in this puppy. That's typical today - everything is USB. No big deal: you can buy USB to serial converters and you can still buy PCI serial cards. I told my customer (the reseller) what he needed and left.
Earlier this week I got a call from one of his regular employees who had gone to the job to install a PCI serial card. He had something unhappy to report: after installing the serial card, the network stopped working.
Of course I suggested pulling the card - he said that he had.. and that the network was still not working. An "ifconfig" showed the correct response, he had triple checked cables and everything else six ways from Sunday and the network was simply unresponsive. Ughh.
I know this tech - he's not a fool, so I knew he had in fact checked everything he could. I asked him to bring me the machine for a look-see and today he did.
My first observations matched his - nothing apparently wrong. But an "lspci -vv" revealed that things were not right..
$ lspci -vv 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit (rev ff) (prog-if ff) !!! Unknown header type 7f
I went right to Realtek and downloaded a new driver. That compiled and installed easily but nothing good happened. To my surprise, an "lsmod | grep r8" showed that "r8169" was loaded and that r8168, although present in the modules directory, was not.
I removed the r8169 files from the directory and rebooted, but r8168 did not load. I did an "insmod" of it and the card popped right up working.. hmmm..
The heck with this: I don't what this is all about (I later found a longish thread at RTL8102EL / Ubuntu 8.04 intermittent failure which describes similar issues with a similar card) so I just jammed my insmod into the top of the network startup script and that fixed it. Good enough for me.
Inasmuch as I had the machine, I also installed the Lava PCI serial card again and tested it and the network at the same time. All was working, so I tore down the machine and will bring it back to them tomorrow.
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More Articles by Anthony Lawrence © 2011-10-16 Anthony Lawrence