Having a multiple network card will not give any redundancy.In redhat Linux you need to configure bonding to accomplish the network level redundancy.Once you have configured the bonding/teaming by using two NIC cards,kernel will automatically detect the failure of any NIC and work smartly according to that without any riot.Bonding can be used for load sharing as well between two physical links.
NIC Details:
[root@mylinz2 network-scripts]# ifconfig -a |grep eth
eth2 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
eth4 Link encap:Ethernet HWaddr 00:0C:29:79:17:04
eth3 Link encap:Ethernet HWaddr 00:0C:29:79:17:F0
[root@mylinz2 network-scripts]#
Goal:
Configure bonding between eth2 and eth4 with name of bond0.
Step 1:
Add the below line in /etc/modprobe.conf to load the bonding module in to kernel.
# alias bond0 bonding
In redhat 6.3 , you need to create new file called “bonding.conf” under /etc/modprobe.d/ with below mentioned line.
# cat /etc/modprobe.d/bonding.conf
alias bond0 bonding
Step 2:
Now time to create a bonding interface configuration file in /etc/sysconfig/network-scripts/ directory like the below one.
[root@mylinz2 network-scripts]# pwd
/etc/sysconfig/network-scripts
[root@mylinz2 network-scripts]# cat ifcfg-bond0
#This is congiguration file for bond0.Used NIC's eth2 & eth4
DEVICE=bond0
IPADDR=192.168.10.25
NETMASK=255.255.255.0
USRCTL=no
ONBOOT=yes
BOOTPRO=none
BONDING_OPTS="mode=0 miimon=100"
[root@mylinz2 network-scripts]#
Step:3
Create a configuration files under “/etc/sysconfig/network-scripts/” for network interfaces if not exists.If exists,have a contents like the below one.
[root@mylinz2 network-scripts]# cat ifcfg-eth2
DEVICE=eth2
HWADDR=00:0C:29:79:17:FA
BOOTPRO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no
[root@mylinz2 network-scripts]# cat ifcfg-eth4
DEVICE=eth4
HWADDR=00:0C:29:79:17:04
BOOTPRO=none
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no
Note:Do not copy paste the content from above output.MAC and DEVICE name will differ for each system.
Step:4
Now restart the network service to load the configuration.
Note:Do not restart the network service without server maintenance window.
[root@mylinz2 ~]# service network restart
Shutting down interface eth2: Device state: 3 (disconnected) [ OK ]
Shutting down interface eth4: Device state: 3 (disconnected) [ OK ]
Shutting down loopback interface: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface bond0: Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/15
[ OK ]
Bringing up interface eth3: Active connection state: activated
Active connection path: /org/freedesktop/NetworkManager/ActiveConnection/16
[ OK ]
[root@mylinz2 ~]#
Step:5
Verify whether “bond0” has come up with IP or not .
[root@mylinz2 Desktop]# ifconfig -a
bond0 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
inet addr:192.168.10.25 Bcast:192.168.10.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe79:17fa/64 Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:22 errors:0 dropped:0 overruns:0 frame:0
TX packets:27 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3843 (3.7 KiB) TX bytes:4169 (4.0 KiB)
eth2 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2031 (1.9 KiB) TX bytes:2064 (2.0 KiB)
eth4 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1812 (1.7 KiB) TX bytes:2105 (2.0 KiB)
In the above output,you can see NIC eth2 and eth4 have flag “SLAVE” and interface “bond0” has flag MASTER.Another thing you note both, the NIC interface will show same MAC address.
Step:6
Performing the live test to ensure bonding is providing the fault tolerance.
First i am removing the LAN cable from eth4 and let see what happens.
[root@mylinz2 Desktop]# ifconfig -a
bond0 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
inet addr:192.168.10.25 Bcast:192.168.10.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe79:17fa/64 Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:22 errors:0 dropped:0 overruns:0 frame:0
TX packets:27 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3843 (3.7 KiB) TX bytes:4169 (4.0 KiB)
eth2 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2031 (1.9 KiB) TX bytes:2064 (2.0 KiB)
eth4 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1812 (1.7 KiB) TX bytes:2105 (2.0 KiB)
Still the bond0 interface is UP and RUNNING fine.At the same time,”RUNNING” flag has disappear from eth4.
Now i have connected LAN cable back to eth4 and pulling out from eth2.
Now i have connected LAN cable back to eth4 and pulling out from eth2.
[root@mylinz2 Desktop]# ifconfig -a
bond0 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
inet addr:192.168.10.25 Bcast:192.168.10.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fe79:17fa/64 Scope:Link
UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
RX packets:22 errors:0 dropped:0 overruns:0 frame:0
TX packets:27 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3843 (3.7 KiB) TX bytes:4169 (4.0 KiB)
eth2 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2031 (1.9 KiB) TX bytes:2064 (2.0 KiB)
eth4 Link encap:Ethernet HWaddr 00:0C:29:79:17:FA
UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
RX packets:11 errors:0 dropped:0 overruns:0 frame:0
TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1812 (1.7 KiB) TX bytes:2105 (2.0 KiB)
Still “bond0” interface running with UP & RUNNING flag.So you have successfully configured bonding on Redhat Linux 6.
To see complete bonding info,use below command.
[root@mylinz2 Desktop]# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)
Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 0
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth2
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:0c:29:79:17:fa
Slave queue ID: 0
Slave Interface: eth4
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:0c:29:79:17:04
Slave queue ID: 0
[root@mylinz2 Desktop]#
To verify the current bonding mode,use below command.
[root@mylinz2 Desktop]# cat /sys/class/net/bond0/bonding/mode
balance-rr 0
You can modify the bonding mode by editing “mode” in the ifcfg-bond0 configuration file.
[root@mylinz2 Desktop]# cat /etc/sysconfig/network-scripts/ifcfg-bond0 |grep -i mode
BONDING_OPTS="mode=0 miimon=100"
POLICY DETAILS
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[root@mylinz2 Desktop]# cat /sys/class/net/bonding_masters
bond0
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