subnet, Tun questions
mack.joseph at epa.gov
Fri Oct 29 13:58:12 BST 2004
this is a fiendlishly complicated setup, that will be impossible for anyone
else, who wasn't part of the design, to fix when anything goes wrong.
I suggest that you make it logically simpler if you want it to be useable.
> What has tripped me up is not understanding the same-subnet issue. As the
> very first step toward implementing this, I initially raised the second
> interface on A (different IP, same subnet) and was then able to connect to
> it via either interface. When I then lowered the second interface,
There's two problems here.
With both NICs assigned an IP,
but one having no cable, since they are on the same network,
you can get to both IPs through the one that is connected.
So unless you want more bandwidth and have some otherway arranged
for half the packets to go to one NIC and half to the other, then
having two NICs on a machine on the same network doesn't get you
The other problem is that Linux is different to other *nixes.
In Solaris, you plumb the device (make it active) and then give
it an IP. In Linux with ifconfig, there is no plumbing stage.
The result is that if you "down" the IP on a linux box, it still
has the IP and you can route to it through the other card.
If you use the more complicated iproute2 tools, then you have this
functionality and can remove the card.
I presume you are using some script to up and down the NICs.
These are fine for normal users who are don't know anything
about their machine and are using all manufacturers settings.
You're doing something else. Use ifconfig or iproute2 directly.
Joseph Mack PhD, High Performance Computing & Scientific Visualization
LMIT, Supporting the EPA Research Triangle Park, NC 919-541-0007
Federal Contact - John B. Smith 919-541-1087 - smith.johnb at epa.gov
More information about the lvs-users