[ On Saturday, July 28, 2001 at 10:54:23 (+0900), itojun@iijlab.net wrote: ]
> Subject: Re: should the default route get a new interface automatically? 
>
> 	Honestly, I don't understand your problem at all.  a diagram is a must.
> 	if you have no routers, you won't need a default route!

Well, there's one router and one default route for one of the networks,
but the other's an isolated private network with no routers.  The server
is not normally a gateway or router (or even really a proxy firewall --
another box has that job).

It's really quite a simple diagram in the basic case:

	-----------+---------   net#1
	           |
	         server
	           |
	-----+-----+---------   net#2
	     |
	  default
	     \
	     \
	  internet

Because each server card is different I've been swapping the networks
between the interfaces to see which works with which switch, etc., and
swapping the interface addresses too of course.  When I do this the
default route gets stuck with the wrong interface (and not everything
works, though IIRC some stuff did work....  next time I try it I'll do
more experiments to see what does work and what doesnt, but I'm not in a
big rush to try again right now on my home server because if the NFS
gets stuck on it again I could end up fighting it half the night to get
it back without a reboot, and I would fight it instead of reboot because
I now know I can get it back if I persist! :-).  (Next time I have
things opened up I'll also try to remember to throw another card in
another server that doesn't normally do any NFS as either client or
server and then I'll be able to do safer experiments with it.)

I've got other similar scenarios at other sites, though the different
nets at some are not quite so isolated (just on different sides of
routers or firewalls) and there extra interface(s) on the server are
usually passive only and there just to sniff on the other segments.

Some sites have a combination of these scenarios.

When you have different types of network cards for each connection it
really is quite often useful to be able to swap which card is connected
to which network (and to swap the interface addresses correspondingly
too of course), all the while not rebooting.  Having to reset the
default route, even though you're not changing anything about it that
you actually specify on the command line, is quite annoying.

-- 
							Greg A. Woods

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