I am trying to get some ideas on what the heck caused a problem with the network at work, and I was hoping someone might have some ideas. Yesterday we were having some major network problems, many machines were completely bogged down. This morning I came in to work to find my linux box unplugged from the network and a note saying to call the network engineering dept. We have a large pool of IP addresses set aside for assignment by DHCP to support laptops and whatnot. Apparently the network problems were caused by a particular MAC address being associated with essentially the entire pool of DHCP-assigned addresses, so the DHCP client boxes were all trying to negotiate for an address and kept getting error messages and trying again. This apparently caused enough traffic that it bogged down the rest of the network. The kicker is that the NIC with the MAC address in question happened to be in my G4 box running linux (yellowdog, 2.2.17 kernel). It was a D-Link 530TX NIC, if it matters. The linux box was not configured as a DHCP server or client, and both interfaces on the box were configured with static IP addresses. The motherboard interface was eth0 and was set to an address on the corporate LAN. The other NIC was eth1 and was set to an address in the 192.168 range for testing. The machine has been up and running in this configuration since september of last year with no known issues. I made no changes at the time the problems started. My understanding of the evidence is that 1) in the routers my MAC address was associated with hundreds if not thousands of IP addresses. 2) it was sending out packets to all boxes configured via DHCP that there was an IP address conflict and that it in fact owned that IP address (not sure exactly what packet this would be, but I saw a printout of an error message from a DHCP-configured printer). 3) when they pulled my machine off the LAN, the problem stopped. 4) today we pulled the NIC with the MAC address in question and hooked the box back up using only eth0, and everything seems to be working fine. On my box, the linux kernel had no knowledge of the IP addresses, "ifconfig" and "ip addr" both showed just the two addresses assigned to it (I checked it during the problems for work related reasons). /etc/hosts has about 9 entries, all ones that I've put in. Does anyone have any ideas as to what was going on? My only theory is that something is screwy with the card or the drivers, but I have no idea why it would run fine for almost 6 months then suddenly start causing problems. I eagerly await your opinions. Chris - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org
