Issues configuring multiple NICs on Server 14.04

**bluefishkiller79** · April 17th, 2015

Greetings All-

I am posting this in the network section but please feel free to move it to server section if needed.

I am having issues configuring multiple interfaces (as well as virtual IP's) on Server 14.04.

I have 4 physical NICs:
eth0 eth1 eth2 eth3

I confirmed this looking in /sys/class/net and it lists:
eth0 eth1 eth2 eth3 lo

Also an ifconfig lists all the adapters and their proper hardware MAC addresses

When I installed Server 14.04 it gave me the option to configure primary interface so I chose eth0 just to start with assuming once I patch I could go back and configure the additional interfaces.

i have no issues with eth0 and networking is fine. /etc/network/interfaces has this configured:

# The primary network interface
auto eth0
iface eth0 inet static
address 10.110.130.240
netmask 255.255.255.0
network 10.110.130.0
broadcast 10.110.130.255
gateway 10.110.130.1
dns-nameservers 10.110.130.20
dns-search *******.com (I have a real name in here)

As is I have no issues with eth0. First I wanted to try and add a virtual IP onto this interface before configuring eth1, eth2, and eth3 so what I added to /etc/network/interfaces config file is this:

auto eth0:1
iface eth0:1 inet static
address 10.110.130.241
netmask 255.255.255.0
network 10.110.130.0
broadcast 10.110.130.255
gateway 10.110.130.1

Saved the config and restarted the interfaces (also even rebooted as well) however I can not PING the virtual IP. The main IP works fine still. After beating my head on the table for an hour I completely removed the eth0:1 settings and rebooted the server. eth0 at this point is still working fine. Not wanting to continue troubleshooting the virtual IP issue i moved on to trying to configure a different interface. ***Note all NICs are on the same VLAN without any doubt***

I open /etc/network/interfaces and add this into the config (as i know that I have a real interface called eth1 with proper MAC address)

auto eth1
iface eth1 inet static
address 10.110.130.241
netmask 255.255.255.0
network 10.110.130.0
broadcast 10.110.130.255
gateway 10.110.130.1
dns-nameservers 10.110.130.20
dns-search *******.com (I have a real name in here)

I save the config and reboot the server. The server takes FOREVER to come up. Networking at this point is completely broken including eth0. I edit /etc/network/interfaces and remove everything related to eth1 that I have just configured. Save the config and reboot the server (server is in dev not Production so I don't mind a reboot everytime). Server comes right back up with no issue and eth0 is working fine again.

I apologize for the very long post but I wanted to provide as much detail up front as possible. I am at a complete loss right now. I come from a Red Hat shop but now work for a company that uses Ubuntu Server (note that I have no preference to what version of Linux I use). I really feel that I am going crazy at this point. I could care less about the virtual IP but I do need to get the other physical NICs working. Any help would be greatly appreciated!

Best regards,
SysAdmin going crazy over this

**michi1983** · April 17th, 2015

Hi,

please provide this script as well:
http://ubuntuforums.org/showthread.php?t=370108

I got some questions though.
What exactly is your gateway?
Are all your 4 NICs connected to something? (to what?l

Greetz

**bluefishkiller79** · April 17th, 2015

I have applied all updates on this server. it is currently at 14.04.2. Gateway is 10.110.130.1. Server is physically connected to Cisco Nexus 7000. It is running on an a Supermicro server with 4 physical NIC cards. There are other physical servers (HP AIX) connected to this switch. They are 10.110.130.200-239 and they use 10.110.130.1 as their gateway. eth0 is 10.110.130.240 using gateway 10.110.130.1 and I have 3 other IPs available for this server 241 for eth1, 242 for eth2, and 243 for eth3. I can PING other AIX servers with no issues and they can PING my .240 address. The link above seemed to reference wireless troubleshooting. I am trying to configure the other interfaces on my server and that is the issue I am having as I edit the /etc/network/interfaces file. Thank you for any help that you can provide

Thank you

**michi1983** · April 17th, 2015

The name of the script is a little misleading

It gives you ALL the network info you need of your machine incl. hardware, drivers, modules etc. So pls be so kind and provide it anyways

What happens when you set eth1 up with your provided details but leave the last two lines out regarding the DNS.

What does

Code:

dpkg -l | grep resolvconf

say?

**SeijiSensei** · April 17th, 2015

First, don't connect multiple adapters to the same network subnet. It will cause all sorts of routing problems. Use eth1-3 to connect to other networks for which this machine will act as a router, or leave them idle.

Next, try limiting the definition for eth0:1

Code:

auto eth0:1
iface eth0:1 inet static
address 10.110.130.241
#netmask 255.255.255.0
#network 10.110.130.0
#broadcast 10.110.130.255
#gateway 10.110.130.1

Because eth0:1 is just a "virtual" interface, it shares the same network, netmask, broadcast and gateway settings as eth0 itself. Restart networking or reboot, then post the results of ifconfig inside [code][/code] tags.

If you have a firewall enabled on this machine, turn it off for testing purposes.

**bluefishkiller79** · April 17th, 2015

Indeed I did have some serious routing issues going on! All IP's are properly working now and the other physical NICs have been setup on different networks with working IP's as well. I cant' thank you all enough for your quick responses and excellent knowledge. Thank you both for your help!