[RFC] ifconfig: match by link-level address

Louis A. Mamakos louie at TransSys.COM
Mon May 24 14:59:57 GMT 2004


> Well actually you should discuss the necessity of the changes in ifconfig with
> the author of the original posting :) What I proposed was just middle way
> between what he proposed and what I did. I mean if somebody is changing
> ifconfig anyway that way would be easier to implement. However personally
> I did the job without any modification of ifconfig at all.

Sorry if I dropped into the middle of the thread, and replied to the 
wrong message.

> > I'm not sure how much easier "automatic" renaming might be.  You still
> > need some ability to specify policy on what interfaces are renamed
> > (e.g., only 100Base-T ethernet but not 802.11 wireless).
> 
> What I am trying to solve is the situation when you have a box with (say) 4
> etherexpresses and first on them is dead. Then old fxp1 becomes fxp0,
> old fxp2 becomes fxp1 and so on. And now you cannot remotely connect to that
> box abd find out what is going on, that's it.
> 
> So I want automatic renaming during the boot, but I want it controlled:
> "this card will have the name intel0, that on - intel1", and it should 
> leave untouched cards without explicit entry in the renaming config. It
> is the way I did it. Do you see any disadvanatges there?

Sure, I understand what you're after.

> About the media type... well, I believe that if I will pick the MAC-address
> of the card and new name I know what that card is, right? I do ifconfig,
> choose cards I want to rename, and create renaming config. Why do I need to
> specify also media type? Is it possible that my wireless adaptor will have
> the same MAC-adress as my Inter Etherexpress? I believe not.

I mentioned this example because I have more than one PCMCIA 802.11 NIC
cards, and I may not care which one happens to be inserted at any given
time, since they tend to rotate between a couple of different laptop
computers.  For my situation, since there's only one of these things
that can be installed, I don't need to worry about what MAC address it
uses.  In fact, I have my DHCP server set up to hand out very different 
types of addresses based on what card is inserted (either a globally
routed address, or an address that gets NAT'ed on the way out).  So in
this case, the per MAC address policy is done elsewhere.

I think this is a very useful capability; I think that I've also seen
stuff move around when reconfiguring the BIOS, or certainly when moving
cards around.  This capability seems like a more general solution than
buying multiple vendor's cards..

louie



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