I was wondering if anyone had seen and fixed this one:

We have a number of Windows 2003 SP2 based DCs which normally work well. However, sometimes after a warm reboot they fail to correctly initialise their network connections - the cards are enabled and appear to be working correctly but traffic does not flow over the cards. This is the case on both their LAN and iSCSI interfaces.

A subsequent warm reboot fixes the issue (e.g. they start up normally and work fine). Cold Reboots do not appear to cause the problem. We've seen this issue with different hardware, both in terms of the server platform (different models of Dell PowerEdge) and different network cards (broadcom & Intel based NICs). And of course we've tried different versions of drivers for all the network cards we have tried.

There are no windows or 3rd party firewalls running on the servers.

1 Answer 1


Just a shot in the dark here, but what do your switches say is going on? Do you see any entries about the port being shutdown because of attempted mac spoofing or other security issues? Are the MAC addresses in the MAC table after the first (non-working) reboot?

This smells more like a switching problem then a server/host problem.

  • Hi Scott, thanks for replying. You could be right, and I'll try and collect data on that basis when I can, but it doesn't smell like it to me. The servers are connected to an iSCSI switch and a LAN which are different physical networks with no connection or route between them. The NICs are different h/w for each connection. The iSCSI n/w is based on Dell switches and the LAN on HP switches. I'll check the data because your suggestion is a very reasonable one but it just doesn't 'smell' like a switch issue to me if its affecting both the LAN and iSCSI connections.
    – Rob Moir
    Mar 11, 2010 at 18:06
  • Are you running any kind of virtualization? If so, the hypervisor could be switching your mac address on reboot and that will cause a 20 minute ARP timeout issue for most hosts... Mar 11, 2010 at 21:10
  • We do use virtualisation, but not on the servers in question - they are all bare metal.
    – Rob Moir
    Mar 12, 2010 at 13:16
  • Not sure this really solves my problem but its a perfectly reasonable step in general and I don't see a better answer on the horizon. Thanks for your help Scott.
    – Rob Moir
    Apr 8, 2010 at 12:49

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