Thanks for all your help (was: URGENT! Server can't access net anymore)

[jcallen at narsil.com (Jerry Callen)]

Bill Horne wrote:
> 
> 1. What does Plug-'n'-play do with interrupts?  I always thought they
> were cast in stone until I changed firmware/jumpers on a particular
> card.

No. As I understand it, at system reset the BIOS polls the slots and
assigns I/O "stuff" (IRQs, DMA, channels, whatever) as requested by the
card in each slot. I probably have the details wrong, but that's the 
general idea. The goal is to remove responsibility for this stuff
from the user and have the system figure it out automatically. This
unfortunately screws you if you really want to control the addresses so 
they match what Linux expects. In some cases there are workarounds;
the NICs I've used all come with a utility that allows you to set 
the addresses ("virtual jumpers", as it were), but in my experience
this then breaks things for Windows. Grr.
> 
> 2. Why would swapping the PCI slot cure this problem?  Wouldn't the
> problem follow the card if the interrupts are mismatched?

See above. The card no longer has a jumper-assigned address.

> 3. Does a cable modem require a reset to recognize a new MAC address?
> Does the reset, if needed, have to come from the head end, or can they
> be reset locally?

MediaOne does something from the head end.

However, most (all?) NICs can be told to use an arbitrary ethernet
address; you can set it with ifconfig.

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