Finally, today I had implemented NIC bonding (bind both NIC so that it works as a single device). Bonding is nothing but Linux kernel feature that allows to aggregate multiple like interfaces (such as eth0, eth1) into a single virtual link such as bond0. The idea is pretty simple, get higher data rates and as well as link failover. The following instructions tested on:
- RHEL v4 / 5 / 6 amd64
- CentOS v5 / 6 amd64
- Fedora Linux 13 amd64 and up.
- 2 x PCI-e Gigabit Ethernet NICs with Jumbo Frames (MTU 9000)
- Hardware RAID-10 w/ SAS 15k enterprise grade hard disks.
- Gigabit switch with Jumbo Frame
This server act as a heavy duty FTP, and NFS file server. Each night a Perl script transfer lots of data from this box to a backup server. Therefore, the network would be setup on a switch using dual network cards. I am using Red Hat Enterprise Linux version 4.0. However, the inductions should work on RHEL 5 and 6 too.
Say Hello To Bonding Driver
Linux allows binding of multiple network interfaces into a single channel/NIC using special kernel module called bonding. According to official bonding documentation:
The Linux bonding driver provides a method for aggregating multiple network interfaces into a single logical “bonded” interface. The behavior of the bonded interfaces depends upon the mode; generally speaking, modes provide either hot standby or load balancing services. Additionally, link integrity monitoring may be performed.
Step #1: Create a Bond0 Configuration File
Red Hat Enterprise Linux (and its clone such as CentOS) stores network configuration in /etc/sysconfig/network-scripts/ directory. First, you need to create a bond0 config file as follows:
# vi /etc/sysconfig/network-scripts/ifcfg-bond0
Append the following linest:
DEVICE=bond0 IPADDR=192.168.1.20 NETWORK=192.168.1.0 NETMASK=255.255.255.0 USERCTL=no BOOTPROTO=none ONBOOT=yes
You need to replace IP address with your actual setup. Save and close the file.
Step #2: Modify eth0 and eth1 config files
Open both configuration using a text editor such as vi/vim, and make sure file read as follows for eth0 interface
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
Modify/append directive as follows:
Open eth1 configuration file using vi text editor, enter:
# vi /etc/sysconfig/network-scripts/ifcfg-eth1
Make sure file read as follows for eth1 interface:
Save and close the file.
Step # 3: Load bond driver/module
Make sure bonding module is loaded when the channel-bonding interface (bond0) is brought up. You need to modify kernel modules configuration file:
# vi /etc/modprobe.conf
Append following two lines:
alias bond0 bonding
options bond0 mode=balance-alb miimon=100
Save file and exit to shell prompt. You can learn more about all bonding options by clicking here).
Step # 4: Test configuration
First, load the bonding module, enter:
# modprobe bonding
Restart the networking service in order to bring up bond0 interface, enter:
# service network restart
Make sure everything is working. Type the following cat command to query the current status of Linux kernel bonding driver, enter:
# cat /proc/net/bonding/bond0
Bonding Mode: load balancing (round-robin) MII Status: up MII Polling Interval (ms): 100 Up Delay (ms): 200 Down Delay (ms): 200 Slave Interface: eth0 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:0c:29:c6:be:59 Slave Interface: eth1 MII Status: up Link Failure Count: 0 Permanent HW addr: 00:0c:29:c6:be:63
To list all network interfaces, enter:
bond0 Link encap:Ethernet HWaddr 00:0C:29:C6:BE:59 inet addr:192.168.1.20 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 RX packets:2804 errors:0 dropped:0 overruns:0 frame:0 TX packets:1879 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:250825 (244.9 KiB) TX bytes:244683 (238.9 KiB) eth0 Link encap:Ethernet HWaddr 00:0C:29:C6:BE:59 inet addr:192.168.1.20 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 RX packets:2809 errors:0 dropped:0 overruns:0 frame:0 TX packets:1390 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:251161 (245.2 KiB) TX bytes:180289 (176.0 KiB) Interrupt:11 Base address:0x1400 eth1 Link encap:Ethernet HWaddr 00:0C:29:C6:BE:59 inet addr:192.168.1.20 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 RX packets:4 errors:0 dropped:0 overruns:0 frame:0 TX packets:502 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:258 (258.0 b) TX bytes:66516 (64.9 KiB) Interrupt:10 Base address:0x1480
Read the official bonding howto which covers the following additional topics:
- VLAN Configuration
- Cisco switch related configuration
- Advanced routing and troubleshooting