Two network adapters

Two network adapters

Post by Fred Youn » Tue, 29 Apr 1997 04:00:00



I installed a second network adapter in my machine that 's on the same
network as the first network adapter. I gave the second adapter an IP
address using ifconfig and the machine responds to the second adapter, but
here's the problem. All responses are sent from the first adapter even
though the source IP address is the IP address of the second adapter. What
am I doing wrong?

 
 
 

Two network adapters

Post by Brian Some » Wed, 30 Apr 1997 04:00:00




Quote:> I installed a second network adapter in my machine that 's on the same
> network as the first network adapter. I gave the second adapter an IP
> address using ifconfig and the machine responds to the second adapter, but
> here's the problem. All responses are sent from the first adapter even
> though the source IP address is the IP address of the second adapter. What
> am I doing wrong?

What do you expect it to do ?  It's finding the first routing table
entry and obeying it.

You should add a static route (to localhost) for the new IP number.

--

      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour !

 
 
 

Two network adapters

Post by Ted Mittelstaed » Wed, 30 Apr 1997 04:00:00






> > I installed a second network adapter in my machine that 's on the same
> > network as the first network adapter. I gave the second adapter an IP
> > address using ifconfig and the machine responds to the second adapter,
but
> > here's the problem. All responses are sent from the first adapter even
> > though the source IP address is the IP address of the second adapter.
What
> > am I doing wrong?

> What do you expect it to do ?  It's finding the first routing table
> entry and obeying it.

> You should add a static route (to localhost) for the new IP number.

This will only work for the specified host.

The thing is that assuming your first network adapter is a good one with
the ability to transmit fast enough to saturate the ethernet (most modern
adapters can do this, even ISA ones) then you don't get any faster network
throughput by putting multiple network adapters in the machine and
connecting them to the same physical network.

Your probably confused by some of the schemes that Novell came out with
which put multiple NICs in the server to "double" the bandwith.  What they
didn't tell you is that these had to be plugged into a switching hub that
had special software on it to recognize what was going on.

Network throughput is gotten by dividing the number of hosts over the
network bandwith.  The only way to modify throughput is by changing one of
these two
variables.  You can either reduce the number of hosts by segmenting them
into additional physical networks using either switching or routing, or you
can increase the bandwith by going to 100baseT or some such.

 
 
 

1. Two network adapters on seperate networks problem

Greetings. Here's my situation: I have a PC running SuSe 9.3 that has
two NIC's. One of these is configured with a static IP such as:
device: eth0
IP: 10.9.81.204
Subnet Mask: 255.255.255.192
Default Gateway: 10.9.81.193

This is an "isolated" network. By this I mean that the routers on this
network have extensive access control lists so that only certain
machines on this network can see other machines. There is no access
from this network to the public internet, (the proxy server for the
internet is blocked on this network).

My other NIC is configured to get an IP via DHCP (although I could get
a static IP if that would help). It gets an IP like:
device: eth1
IP: 10.9.16.140
Subnet Mask:255.255.255.0
Gateway: 10.9.16.1

This network does have a connection to the public internet through a
proxy server at IP 10.22.2.100.

I can ping and ssh to machines on both networks. Machines on both
networks can see me, even my samba shares. But, I cannot get to the
public internet from my machine, it seems that my connection to the
proxy server is blocked. I suspect it is because my default gateway is
going through eth0 onto the private network. If I remove the default
gateway entry, then I can get to the public internet, but I loose the
connection I have to machines on the "isolated" network network.

Is there some sort of solution that will allow me to have my default
network traffic go to the eth1 adapter configured via DHCP, and still
allow traffic to go through eth0 for the isolated network. Note that
there are about 35 machines I need to connect to on the isolated
network. They have IP's in the 10.9.##. domains, where ## is 52-69. So,
maybe I could use a bunch of route statements to forward traffic to
these machines through the gateway of eth0? Or, maybe I just need to
use a route command to direct the proxy out eth1? I'm kind of at a loss
here, this sort of networking is not my strong suit.

Any help here is greatly appreciated! Thanks!

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