Channel Bonding , load balancing, CentOS 4.x Options

[Robert83]

Hi,

I've needed to double the avaiable bandiwdth of one of our wireless links, and because we had another pair of same speed wireless units (approx 400kbyte/s~ speed). I've decided that we would go with 2 wireless links bonded together providing some sorta load balancing. Preferably double speed, and failover (though this is not working well with wireless, but these units haven't had problems with their connection for the last 4-5 months).

Anyway the way you begin is quiet simple :

PC1

1. Get youreself one CentOS 4.x CD1 , nomatter which version, but latest would be preferable.
2. You install the system using the minimal install
3. Once the system is installed you make sure everything is upgraded to latest version by running the
following command.

CODE

     yum upgrade

4. Let's imagine the machine we are working on has the IP address of 192.168.1.114 , first you'll need to
edit your /etc/modprobe.conf , adding these 2 lines just above the aliases for your ethernet cards.

CODE

     alias bond0 bonding
     options bond0 miimon=0 arp_interval=2000 arp_ip_target=192.168.1.113 mode=0

5. Now we will need to setup the interfaces correctly , you just go to /etc/sysconfig/network-scripts/,
I have three interfaces one named eth0 and the other named eth1 and eth2, these two will be bonded
together, and then bridged with eth2, you'll need to edit them like this in order to make the bonding
work.

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

CODE

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

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

CODE

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

/etc/sysconfig/network-scripts/ifcfg-eth2

CODE

    DEVICE=eth2
    ONBOOT=yes
    BOOTPROTO=none

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

CODE

    DEVICE=bond0
    BOOTPROTO=none
    ONBOOT=yes

6. The final step before finishing the setup on the first system is to make sure that on next
reboot the system actualy creates the bridged interface with the correct ip address, in order to make
this happen add the following lines to your /etc/rc.d/rc.local file

/etc/rc.d/rc.local

CODE

    /usr/sbin/brctl addbr my
    /usr/sbin/brctl addif my bond0
    /usr/sbin/brctl addif my eth2
    /sbin/ifconfig bond0 0.0.0.0
    /sbin/ifconfig eth2 0.0.0.0
    /sbin/ifconfig my 192.168.1.114 netmask 255.255.255.0 up
    /sbin/route add default gw 192.168.1.249

With this the first computer is done, now let's move to the next one, in order to preserve lines here, I will
only tell which files to edit nothing more.

PC2

/etc/modprobe.conf

CODE

alias bond0 bonding
options bond0 miimon=0 arp_interval=2000 arp_ip_target=192.168.1.114 mode=0

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

CODE

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

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

CODE

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

/etc/sysconfig/network-scripts/ifcfg-eth2

CODE

DEVICE=eth2
ONBOOT=yes
BOOTPROTO=none

/etc/rc.d/rc.local

CODE

/usr/sbin/brctl addbr my
/usr/sbin/brctl addif my bond0
/usr/sbin/brctl addif my eth2
/sbin/ifconfig bond0 0.0.0.0
/sbin/ifconfig eth2 0.0.0.0
/sbin/ifconfig my 192.168.1.113 netmask 255.255.255.0 up
/sbin/route add default gw 192.168.1.249

And finally some information :

After you've made the necesary configs to both pc's connect them together make sure that eth0 goes to
eth0 on other pc, and eth1 goes to eth1 on other pc.

You can now connect 2 test machines to both sides of the bonding bridges like this

pc1---eth2---bond---my---------my---bond2---eth2---pc2

and you can check out the speed (you would get better results with linux machines).

I've tested the bonding this way, I've setup a ftp server on bond2 and using wget I downloaded a 200MB file
to bond, the speed was 20MB/s~ on a 2x100mbit/s line.

I've also tested bonding with wireless (and in fact still working with it) 2x400kbyte/s wireless links resulted
in a much more responsive 700kbyte/s wireless link (wireless aint doubled... ahh, but that's because
wireless works in a strange way most of the time).

NOTE : I've had a hell of time making the 2 wireless links work together nicely, in order to make
them work in a bonding scenario like this, I had to enable a certain option called MAC ADDRESS CLONING,
and had to use different SSID , and different CHANNEL.

Sincerely
Robert B