Tuesday, 17 April 2018

How to Setup Network Bridge with NIC bonding in RHEL7/Centos7



Network Bridge: A software bridge can be used within a Linux host in order to emulate a hardware bridge. This network bridge allows virtual machines to have access to the external network and vice-versa and allow communicating between different Network VLANs [Trunk VLANs].


The bridge is used during the configuration of KVM Server (Kernel-based Virtual Machine) and need to communicate between different Network VLANs. Virtual Machine launched in KVM is use the default network with NAT networking which is mapped to the host network to provide external network connectivity.

NIC bonding:
 NIC Bonding enables two or more network interfaces to act as one interface, to provide higher data rates and as well as link fail over. Linux kernel features that allows aggregating multiple interfaces. This is a great way of achieving redundancy to a server. If one physical NIC is down or unplugged, it will automatically move resource to other NIC card.

Step 1: Verify/Install Module: Use the following command to verify whether the bridge module is loaded or not.

[root@linuxcnf ~]# modinfo bridge
filename:       /lib/modules/3.10.0-693.el7.x86_64/kernel/net/bridge/bridge.ko.xz
alias:          rtnl-link-bridge
version:        2.3
license:        GPL
rhelversion:    7.4
srcversion:     188FE82E919189D8DCBCF21
depends:        stp,llc
intree:         Y
vermagic:       3.10.0-693.el7.x86_64 SMP mod_unload modversions
signer:         CentOS Linux kernel signing key
sig_key:        DA:18:7D:CA:7D:BE:53:AB:05:BD:13:BD:0C:4E:21:F4:22:B6:A4:9C
sig_hashalgo:   sha256
[root@linuxcnf ~]#

If the module is not loading, you can load it using the following command:

[root@linuxcnf ~]# modprobe --first-time bridge

Also, we need to install bridge-utils for controlling the network adapters. Install the bridg-utils as below:

[root@linuxcnf ~]# yum install bridge-utils

Step 2: Create A Network Bridge: Create a file named “ifcfg-br0” in the “/etc/sysconfig/network-scripts/“and append the parameters as below:

[root@linuxcnf ~]# vi /etc/sysconfig/network-scripts/ifcfg-br0
DEVICE=br0
TYPE=Bridge
BOOTPROTO=none
IPADDR=192.168.43.105
NETMASK=255.255.255.0
GATEWAY=192.168.43.1
ONBOOT=yes
NM_CONTROLLED=no

Here, you need to replace IP address as per actual setup IP addresses.

Similarly, create and modify bond0, eth0 and eth1 interfaces configuration files and append the below parameters as below:
Step 3: Create other configuration files: We need to create these below files in /etc/sysconfig/network-scripts/ directory and append the below parameters on respective files:

[root@linuxcnf ~]# vi /etc/sysconfig/network-scripts/ifcfg-bond0
DEVICE=bond0
NAME=bond0
TYPE=Bond
ONBOOT=yes
BRIDGE=br0
BOOTPROTO=none
NM_CONTROLLED=no
BONDING_OPTS="mode=1 miimon=100"

[root@linuxcnf ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
TYPE=Ethernet
USERCTL=no
ONBOOT=yes
BOOTPROTO=none
NM_CONTROLLED=no
MASTER=bond0
SLAVE=yes

[root@linuxcnf ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
TYPE=Ethernet
USERCTL=no
ONBOOT=yes
BOOTPROTO=none
NM_CONTROLLED=no
MASTER=bond0
SLAVE=yes
Step 4: Load bond driver/module: Check bonding driver/module is loaded for NIC-bonding interface (bond0) is bringing up. First, load the bonding module, enter:

[root@linuxcnf ~]# modprobe bond
Step 5: Restarting Network service: Now we can restart the network service in order to bring up bond0 interface:

[root@linuxcnf ~]# service network restart

Step 6:  Verify Configuration: Enter the below commands to verify the bridge status from Linux kernel bonding driver:

[root@linuxcnf ~]# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.a0d3c1f45d2c       no              bond0
                                                        vnet0
                                                        vnet1
virbr0          8000.52540098014f       yes             virbr0-nic
[root@linuxcnf ~]#

Enter the below commands to verify the bond status from Linux kernel bonding driver:

[root@linuxcnf ~]# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 14:f6:34:23:fd:1a
Slave queue ID: 0
Slave Interface: eth1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 14:f6:34:32:fd:1b
Slave queue ID: 0
[root@linuxcnf ~]#

[root@linuxcnf ~]# ifconfig
bond0: flags=5187<UP,BROADCAST,RUNNING,MASTER,MULTICAST>  mtu 1500
        inet6 df80::32e1:71df:fe54:df0a  prefixlen 64  scopeid 0x20<link>
        ether 14:f6:34:23:fd:1a  txqueuelen 1000  (Ethernet)
        RX packets 7821329  bytes 7202213190 (6.7 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5083957  bytes 1189921931 (1.1 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.43.105  netmask 255.255.255.0  broadcast 192.168.43.1
        inet6 df80::32e1:71df:fe54:df0a  prefixlen 64  scopeid 0x20<link>
        ether 14:f6:34:23:fd:1a  txqueuelen 1000  (Ethernet)
        RX packets 6231499  bytes 3275041689 (3.0 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1994973  bytes 485209953 (462.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
eth0: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1500
        ether 14:f6:34:23:fd:1a txqueuelen 1000  (Ethernet)
        RX packets 1293869  bytes 113523260 (108.2 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16
eth1: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1500
        ether 14:f6:34:32:fd:1b txqueuelen 1000  (Ethernet)
        RX packets 4937630  bytes 3161518429 (2.9 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1994973  bytes 485209953 (462.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 17
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 4276  bytes 264988 (258.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4276  bytes 264988 (258.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
[root@linuxcnf ~]#

Network bridge configuration with NIC bonding is done!!

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