At 08:41 AM 20/02/97 -0500, Richard Brackett wrote:
>I don't believe that you are going to be able to make that configuration
work.
>How is TCP/IP supposed to choose
>which adapter to use when talking to that subnet? Any multi-adapter
configuration
> I've seen or implemented needed
>two different subnets to work. I've done this under various unix flavors,
Netware, and NT.
>Most OS's will allow
>multiple same-subnet addresses to a single card, but not two different
cards.
>
>Others may have different experiences and I'd be interested in hearing
from anyone with more
>depth of knowledge on the subject.
>
>Richard
>
>>>> Ruben Sajnovetzky <ruben @
is .
com .
ar> 02/19/97 11:59am >>>
>+ I wants to configure the two ATM interfaces using same a subnet
>+ address(192.11.214.0) on a SGI workstation, for example, one is
>192.11.214.10
>+ and another is 192.11.214.11. But I found if I assigned the two ATM
interfaces
>+ into same a subnet, the IRIX system couldn't work correctly. If I
assiged the
>+ two ATM interfaces into two different subnet(ex: 192.11.214.10 and
>+ 192.11.215.20), our IRIX system could work correctly. Do you know that two
>+ network interfaces(such as ATM, ethernet or FDDI) in a UNIX machine can be
>+ assigned into same a subnet? If can, how should I configure?
100% correct. So lets cheat.
First I'm going to pick the network address on the class C subnet you
describe.
I'm not going to use 10 and 11, I'm going to use 10 and (just to be
preposterous)
255-10 = 245, which was my old house number.
Now I'm going to squint very hard and make the class C go away.
With this squint, you no longer have a 24 bit subnet mask, 255.255.255.0
(or ff.ff.ff.00) but instead a 26 bit mask (ff.ff.ff.80).
OK, I told you I was going to cheat.
>From the point of view of this machine, its on TWO subnets, each of which
is half a class C. This is because when you did and ifconfig on each of the
ports you did the appropriate mask as well.
But that's only for this machine. All the other single ported machines
on the class C don't suffer from this.
I do say suffer. As Richard Brackett said, how are you going to make this
work?
What good will it do you? Are you trying to do load balancing? Split the
load between
two cards? Well this isn't going to do that. If that's your problem you
need to
figured out WHY you need more bandwidth. Run a snooper and see all the
junk you're
putting out. Turn off rwhod, and all those other noisy protocols like NIS
and NFS. ;-)
Putting on my consulting hat for a moment, lets ask two questions:
1. What are you trying to do?
Oh yes, put two cards on the same machine on the same subnet.
2. What are you trying to ACHEIVE? What is your ENDPOINT OBJECTIVE?
Sorry that's three. Assume the last two are different ways of asking the
same thing.
OBTW: Some RFC and hence some routers and IP stacks may not take kindly to
this
chopping of subnets on non-8-bit boundaries, CIDR not withstanding.
Some may say that all of the subnet 0 part simply isn't accessible.
Your milage may vary. All I can say is that it has worked for me.
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