how to config NICs with only one IP or even no IP

[frederick van tagero]

I noted that some system been configured with more than one NIC in only one IP, or even no ip at all, act as only one hub.

I wonder how to configure that.

thanks in advance

frederick van targero

[Kodjo Agbenu · Accepted solution]

Hi Frederick,

Your question seems confusing to me.

Normally, two NICs cannot be configured the same IP.

There is only one case where this is permitted : when using the "bonding" driver.

Bonding is used to create an aggregate between 2 or several NICs. This adds the following properties : failover, load balancing and bandwidth increase.

To configure bonding, stop the network, then edit the following configuration files :

/etc/sysconfig/network-scripts/ifcfg-eth0 :

DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none

/etc/sysconfig/network-scripts/ifcfg-eth1 :

DEVICE=eth1
USERCTL=no
ONBOOT=yes
BOOTPROTO=none
SLAVE=yes
MASTER=bond0

/etc/sysconfig/network-scripts/ifcfg-bond0 :

DEVICE=bond0
USERCTL=no
ONBOOT=yes
BOOTPROTO=none
IPADDR=...
NETMASK=...
NETWORK=...
BROADCAST=...
GATEWAY=...

/etc/modules.conf :

alias bond0 bonding


Restart the network, then type "/sbin/ifconfig -a". You will find that both eth0 and eth1 have the same IP address.

Good luck.

Kodjo

[frederick van tagero]

hi Kodjo,

yeah, what I seem some guys config the linux as "transparent mode", it is bonding done? however, I noticed they never need to restart the system?

regards,
Frederick van targero

[Manuel Wolfshant]

I assume that you refer to what is called as 'bridging'. You should read Linux BRIDGE-STP-HOWTO (http://www.tldp.org/HOWTO/BRIDGE-STP-HOWTO/) and http://www.linux.org/docs/ldp/howto/mini/Bridge+Firewall.html

[Caesar_3]

Hello!

For restart the network you don't need to
do restart to the computer all you need
is to restart the NIC you do it by:

ifdown eth0
change what you want in configuration
ifup eth0

And you have the changes without restart.

Caesar