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Old 05-22-2002, 11:30 AM   #1
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Unhappy Networking issue, possible IRQ conflict

I am installing a Gigabit Ethernet cards (SysKonnect SK-9843 cards) into two differe Linux servers, running Red Hat 7.2. Each server is identical in hardware specs (Intel motherboards), software - Red Hat 7.2, kernel 2.4 and are sharing a 100 Mb Ethernet LAN with two Windows 2000 boxes. This LAN is being used for testing of software.

I power downed the Linux boxes, installed the GE cards, booted the servers up, and configured the GE cards using the New Hardware tool that activates with the Linux server discovers new hardware. I assigned valid IP networking addresses to the cards, and continued the bootup. The 10/100 LAN that all of my servers are on (2000 and RH Linux) have static IP addresses, no DHCP involved.

The first server came up fine, and I was able to ping the other Linux server, and the Windows 2000 boxes. Using the Windows 2000 boxes, I was able to ping both the IP address for the 10/100 ethernet port (which is built into the motherboard), and the Gigabit ethernet card.

The second server continued to boot up fine, but with both the 10/100 port and the Gigabit ethernet card (the SysKonnect card) up, I was unable to access the 10/100 LAN. If I disabled the Gigabit ethernet card at start-up or physically removed the Gigabit ethernet card from the server (and from the hardware configuration), I was able to access the 10/100 LAN, and ping the other servers (Linux server #1 and both Windows 2000 servers, and vice versa). If I re-enable the Gigabit ethernet card or reinstall it, I lose the other port, the 10/100 port. It would seem to me to be that there is resource sharing conflict, but is there a way to check this in Linux. In the Windows 2000 world, I would check for IRQ conflicts.

Do you know how to check for IRQ conflicts in Linux? Is there another issue at work here that I am unaware of? Or this a networking issue that I am not aware of.

I would appreciate any help


Old 05-22-2002, 12:55 PM   #2
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you can try using the command dmesg
Old 05-22-2002, 01:21 PM   #3
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Can you boot your system into another OS, eg windoze with the 2 NIC cards attached, and check for the IRQ, so that u can set them respectively in Linux
Old 05-22-2002, 01:33 PM   #4
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To see what the current IRQ usage under linux is at any time:

cat /proc/interrupts

I use this to figure out the free IRQ when dealing with old ISA gear, but this problem on a newer card is an oddity. Maybe the mobo doesn't like sharing. Like Tricky said, the kernel hardware report of dmesg is going to be the most useful debugger as is ifconfig. Bringing the cards up and down through the GUI is probably a real time suckage, just use ifconfig to bring them up and down and you should be able to test your way through this quicker.


Old 05-22-2002, 04:24 PM   #5
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Talking solution

Thx everyone for the suggestions. After using the suggestions, I was able to rule out the possibility of IRQ conflict.

Basically the 10/100 ports are for LAN Mgmt and Server Connectivity. The Gigabit ethernet cards are for WAN Data Mirroring testing I am simulating. The fix was to change the Gigabit ethernet cards to a separate subnet, different from the Mgmt. LAN subnet.

Once I did this, I was able to get everything running as I needed, 10/100 for Mgmt. and Gigabit for the WAN testing.

Why this worked, I have no idea, so if somebody wants to post an explanation, that would probably be beneficial to future posters. A vendor emailed me the final solution, but I thought it be best to share with everyone.


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