2 NICs on physical machine

trackstar2000 · 06-19-2013, 01:41 PM

Hello,

I will be working on Centos 6.4 with 2 NIC configuration. One IP will be 192.168.XX.XX and the other 134.XX.XX.XX.

Are there any specifics I should be aware of when I enter them in the Network settings. I haven't worked with linux with 2 NICs setup.

TIA,
TS

acid_kewpie · 06-19-2013, 02:04 PM

having two nics is not interesting. It's what you're actually doing with them them affects things. You need to give us the full picture if you want advice. Only thing that people seem to always want to do is to have two default gateways. I still have no idea what they think that means.

trackstar2000 · 06-19-2013, 02:15 PM

Quote:

Originally Posted by acid_kewpie

having two nics is not interesting. It's what you're actually doing with them them affects things. You need to give us the full picture if you want advice. Only thing that people seem to always want to do is to have two default gateways. I still have no idea what they think that means.

One is for the public facing and other is internal. For internal, it will communicate with our backup server. It is the network guy's idea

. A main concern is to make sure the machine communicates to the backup server on the correct NIC. We use EMC Networker.

acid_kewpie · 06-19-2013, 02:17 PM

perfectly logical idea. Well done him. So what's the concern?

jefro · 06-19-2013, 02:53 PM

The rules of TCP/IP don't change in linux. The issue would be usually a combination of IP address and subnet mask. That should allow IP range choice to correct endpoint within subnet. If it goes outside of subnet then you'd have to add in a gateway address. This may be confusing if both nic's need a gateway. That could be fixed with some settings. Usually internal lan doesn't use a gateway but tell us the exact topology.

Linux versions may put gateway and other settings in different places. It may be automated on some dhcp or may have to have some network manager settings changed.

frieza · 06-19-2013, 04:53 PM

Quote:

Originally Posted by trackstar2000

One is for the public facing and other is internal. For internal, it will communicate with our backup server. It is the network guy's idea

. A main concern is to make sure the machine communicates to the backup server on the correct NIC. We use EMC Networker.

good idea, I've done something like that myself except it was a web server talking to a back-end database server and file server.

as mentioned, as long as the two nics are assigned to two distinct discrete networks and the backup server is configured to belong to the same network as the internal nic than it should work
something like this:

Code:

{public facing}
       |{192.168.2.0/255.255.255.0}          {192.168.1.0/255.255.255.0)  
       [public interface]---{machine}---[private interface]---[nic]{backup server}
                                             192.168.1.1           192.168.1.2

those are separate networks, any request to 192.168.1.2 from 192.168.1.1 should go to the backup server

trackstar2000 · 06-20-2013, 01:01 PM

It turns out the network guy used a cicso asa (used NAT). I only had to use one physical NIC which is 10.XX.XX.XX. When I am logged in, the browser shows my IP address as 134.XX.ZZ.ZZ (Same iP I used for SSH).

We are trying to get backup to run (our backup server is on 134.XX.YY.YY)

acid_kewpie · 06-21-2013, 02:19 AM

your backup server is on a public IP? OK now THAT is really really dumb.

But is there an issue here that you need help with or are we done?