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Old 06-15-2017, 01:29 PM   #1
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Registered: Jun 2017
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Ubuntu IP issue

Hello all

I am currently running ubuntu 14.04.1 LTS which I installed today on my dell poweredge R210 for testing purposes. I configured both NIC cards, the first one on a static IP address and the second on DHCP. My problem is when I disconnect my ethernet cable from the static IP address it doesn't allow me to Ping from my other connection via DHCP. From what I know I should still be able to ping from the second interface. help pleaase.

A separate issue from this, why cant I set a static IP on ubuntu 16.04 without rebooting the machine???

This is my configuration:

Last login: Thu Jun 15 14:11:46 2017 from
bi@ubuntu:~$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto em1
iface em1 inet static

#The secondary network interface
auto em2
iface em2 inet dhcp
Old 06-15-2017, 03:40 PM   #2
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Registered: Dec 2014
Location: Montreal, Quebec and Dartmouth, Nova Scotia CANADA
Distribution: Arch, AntiX, ArtiX
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Hi stickyrice ... A few questions to help us help you:

- Are both NICs wired ? ... or is the DHCP-configured (secondary) interface wireless ?

- Are you expecting both connections to be live simultaneously ? To me, this would be an unusual objective, unless you are connecting to 2 different networks, and even then, the setup would be quite particular.

- If you are NOT expecting both to be live simultaneously (most likely), when unplugging the ethernet cable from the primary interface, are you also instructing your system to set it DOWN ? For example:

# ip link set em1 down
would be the command I would use in Arch ... Are you then issuing a command to bring the secondary interface UP to obtain an IP address ?

- What network configuration system are you using ? I am afraid I'm not that familiar with Ubuntu.

Catch up with you once you get back to us ...

Last edited by Rickkkk; 06-15-2017 at 03:43 PM.


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