Bonding Multiple Network Interfaces on SLES 10

Author :
Sanjeev Gupta.

Overview:

This article has the steps to bond two network interfaces on a SLES 10 server to increase network throughput or to achieve NIC failover for high availability configurations.

1. Find out whether the network card supports miimon, ethtool monitoring. This will determine the bonding module options for our configuration at other places.

   # ethtool eth0

   If you see something like below, you can use miimon mode.

   Settings for eth0
   Current message level: 0x000000ff (255)
   Link Detected: yes

   

   Click to view.

2. Configure your network cards in yast, and configure the first network card with the IP address and other network information that you want the bonded interface to have. Configure the other network card with a dummy IP addresses. As we won’t be using this dummy configuration anywhere so it doesn’t matter.
3. Go to a terminal window and cd to /etc/sysconfig/network/ and make a copy of configuration file of the network card you just configured with the i.p address and other network information. Network configuration file-name starts with name ifcfg-eth-id*.We will be using this file as a template for our bonding configuration. Name of the destination file should be ifcfg-bond0 for the first bonded pair.

   # cd  /etc/sysconfig/network/
   # ls ifcfg-eth-id*
   # cp ifcfg-eth-id-<your Ist network card> ifcfg-bond0

   

   Click to view.

   Note: You can use yast2 network configuration window to find out config file of your Ist network card. Note down the mac address of the first network card from yast and compare it with the names of ifcfg-eth-id-* files which have the mac address of card appended in their names.
4. We will use the above created “ifcfg-bond0” as a template to start with. We need to discover the PCI bus IDs for the two ‘real’ NICs. At the prompt. For this cd go to:/etc/sysconfig/network and type “grep bus-pci ifcfg-eth-id*”.

   # cd  /etc/sysconfig/network
   #  grep bus-pci ifcfg-eth-id*

   You should see something like this.

   :_nm_name='bus-pci-0000:05:00.0'
   :_nm_name='bus-pci-0000:04:00.0'

   

   Click to view.

5. The above command gives us the addresses of the two physical network cards. Using this information, we can now modify our ifcfg-bond0 file to tell it the card details to use.Add in a section like this at the end of the ifcfg-bond0 file and save it.

   BONDING_MASTER=yes
   BONDING_SLAVE_0='bus-pci-0000:05:00.0'
   BONDING_SLAVE_1='bus-pci-0000:04:00.0'

   

   Click to view.

6. The next step is to specify to the system which driver to load when bond0 if referenced. To do this, open the file /etc/modprobe.conf.local.

   # vi /etc/modprobe.conf.local

   Add the following lines in the end of file and save it

   alias bond0 bonding
   options bonding miimon=100 mode=0 use_carrier=0

   

   Click to view.

   The above specifies that when we see bond0 being referenced, we need to load the bonding driver with the parameters outlined. The ‘miimon=100’ value tells the driver to use mii monitoring, watching every 100 milliseconds for a link failure. The ‘mode’ parameter specifies one of four bonding policies.

   Note: The default is round-robin. Possible mode values are:
   0 Round-robin policy: Transmit in a sequential order from the first available slave through the last. This mode provides load balancing and fault tolerance.
   1 Active-backup policy: Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond’s MAC address is externally visible on only one port (network adapter) to avoid confusing the switch. This mode provides fault tolerance.
   2 XOR policy: Transmit based on [(source MAC address XOR’d with destination MAC address) modula slave count]. This selects the same slave for each destination MAC address. This mode provides load balancing and fault tolerance.
   3 Broadcast policy: transmits everything on all slave interfaces. This mode provides fault tolerance.
7. We need to now clear out the old ifcfg files that we don’t need. Just delete or move for backup the ifcfg-eth-id* files in the /etc/sysconfig/network directory and restart the network.

   # cd /etc/sysconfig/network
   # mv ifcfg-eth-id* /backup
   # rcnetwork restart

   

   Click to view.

8. If you have done the configuration correctly, you will see the bond0 interface appearing with the correct IP address and ‘as bonding master’, followed by two ‘enslaving eth’ lines. Verify the configuration using ifconfig and you’ll notice the MAC addresses for all the cards are identical, just as the IP addresses for eth0, eth1 and bond0 are identical.
   

   Click to view.

9. Test your configuration by plugging in network cables in both network cards and start ping to another machine on network. Now plug out one network cable from card-2 and verify that ping is still going on fine. Now plug in the cable to card-2 and remove the cable from card-1. If the ping still goes on fine, your configuration and setup is correct.
10. If needed, you can repeat the process for a second bond, just modify the modprobe.conf.local with an ‘alias bond1 bonding’ line and carry on as before.