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    FAQ | 13 min read

    LACP bonding configuration by using NMCLI (CENTOS or RHEL 7)

    Pre-Requesites

    We consider creating a Bond0 interface which will do a bonding from the two following physical interface : em2 and em3.

    Different Bonding mode can be applied (this depends of the Switch capability).

    • Mode 0 (balance-rr): This mode is also known as round-robin mode. Packets are sequentially transmitted and received through each interface one by one. This mode provides load balancing functionality.
    • Mode 1 (active-backup): This mode has only one interface set to active, while all other interfaces are in the backup state. If the active interface fails, a backup interface replaces it as the only active interface in the bond. The media access control (MAC) address of the bond interface in mode 1 is visible on only one port (the network adapter), which prevents confusion for the switch. Mode 1 provides fault tolerance.
    • Mode 2 (balance-xor): The source MAC address uses exclusive or (XOR) logic with the destination MAC address. This calculation ensures that the same slave interface is selected for each destination MAC address. Mode 2 provides fault tolerance and load balancing.
    • Mode 3 (broadcast): All transmissions are sent to all the slaves. This mode provides fault tolerance.
    • Mode 4 (802.3ad): This mode creates aggregation groups that share the same speed and duplex settings, and it requires a switch that supports an IEEE 802.3ad dynamic link. Mode 4 uses all interfaces in the active aggregation group. For example, you can aggregate three 1 GB per second (GBPS) ports into a 3 GBPS trunk port. This is equivalent to having one interface with 3 GBPS speed. It provides fault tolerance and load balancing.
    • Mode 5 (balance-tlb): This mode ensures that the outgoing traffic distribution is set according to the load on each interface and that the current interface receives all the incoming traffic. If the assigned interface fails to receive traffic, another interface is assigned to the receiving role. It provides fault tolerance and load balancing.
    • Mode 6 (balance-alb): This mode is supported only in x86 environments. The receiving packets are load balanced through Address Resolution Protocol (ARP) negotiation. This mode provides fault tolerance and load balancing.

    Description

    Backup the existing interfaces that you plan to configure as bond slaves by using the following commands:

    [root@nodeum network-scripts]# ifdown em2 ; ifdown em3
    [root@nodeum network-scripts]# cd /etc/sysconfig/network-scripts
    [root@nodeum network-scripts]# mkdir BACKUPDIR
    [root@nodeum network-scripts]# mv -v ifcfg-em2 ifcfg-em3 ./BACKUPDIR

    Check the status of the interfaces to be configured as bond slaves by using the following commands:

    [root@nodeum network-scripts]# nmcli con
    NAME        UUID                                  TYPE            DEVICE
    [root@localhost network-scripts]# nmcli con
    NAME  UUID                                  TYPE      DEVICE
    em1   28338337-f543-4122-83c3-dc4bb132c7d2  ethernet  em1
    em2   4504020b-0a37-47d0-a159-faeafdf3208e  ethernet  --
    em3   c0a6aa70-d52a-4b4f-8a25-a817b822876a  ethernet  --
    em4   cb61666c-13fd-4208-ab38-c0c2507b11d8  ethernet  --
     
    [root@nodeum network-scripts]# ethtool em2 |grep "Link detected"
    Link detected: yes
    [root@nodeum network-scripts]# ethtool em3 |grep "Link detected"
    Link detected: yes
    • Create a bond interface by using the bonding options (explained in the prerequesite) :
    [root@nodeum network-scripts]]#nmcli con add type bond con-name bond0 ifname bond0 mode 802.3ad ip4 x.x.x.x/yy
    Connection 'bond0' (9775d497-bb24-4db5-b9d9-c155ac5fa510) successfully added.
    [root@nodeum network-scripts]#nmcli con mod id bond0 bond.options mode=802.3ad,miimon=100,lacp_rate=fast,xmit_hash_policy=layer2+3
    [root@nodeum network-scripts]#nmcli con mod id bond0 802-3-ethernet.mtu 9000
    [root@nodeum network-scripts]#nmcli conn del  4504020b-0a37-47d0-a159-faeafdf3208e
    Connection 'em2' (4504020b-0a37-47d0-a159-faeafdf3208e) successfully deleted.
    [root@localhost network-scripts]# nmcli conn del  c0a6aa70-d52a-4b4f-8a25-a817b822876a
    Connection 'em3' (c0a6aa70-d52a-4b4f-8a25-a817b822876a) successfully deleted.
    [root@nodeum network-scripts]#nmcli con add type bond-slave ifname em2 con-name em2 master bond0
    Connection 'em2' (e13bffae-2a18-436f-874e-f91824947442) successfully added.
    [root@nodeum network-scripts]#nmcli con add type bond-slave ifname em3 con-name em3 master bond0
    Connection 'em3' (6dcb263d-03ca-4203-854c-54a7276d1a2f) successfully added.

    • Restart the NetworkManager service by using the following command:
     
    [root@nodeum network-scripts]#systemctl restart NetworkManager

    • Check the status of the bond and slave interfaces to verify that the bond0 interface is running by using the following commands:
    [root@nodeum network-scripts]#nmcli con
    NAME        UUID                                  TYPE      DEVICE
    em1         28338337-f543-4122-83c3-dc4bb132c7d2  ethernet  em1
    em2         4504020b-0a37-47d0-a159-faeafdf3208e  ethernet  em2
    em3         c0a6aa70-d52a-4b4f-8a25-a817b822876a  ethernet  em3
    em4         cb61666c-13fd-4208-ab38-c0c2507b11d8  ethernet  --
     
    [root@nodeum network-scripts]# nmcli con up uuid 5a21933b-0c60-4aa6-93b2-b0e4dab6747e
    Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/8)
     
    [root@nodeum network-scripts]#nmcli con
    NAME        UUID                                  TYPE      DEVICE
    bond0       5a21933b-0c60-4aa6-93b2-b0e4dab6747e  bond      bond0
    em1         28338337-f543-4122-83c3-dc4bb132c7d2  ethernet  em1
    em2         4504020b-0a37-47d0-a159-faeafdf3208e  ethernet  em2
    em3         c0a6aa70-d52a-4b4f-8a25-a817b822876a  ethernet  em3
    em4         cb61666c-13fd-4208-ab38-c0c2507b11d8  ethernet  --

    • After the configuration is complete, check the output of the following commands to verify that the bond0 interface is active and no error is found:
    [root@localhost network-scripts]# cat /proc/net/bonding/bond0
    Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
     
    Bonding Mode: IEEE 802.3ad Dynamic link aggregation
    Transmit Hash Policy: layer2 (0)
    MII Status: up
    MII Polling Interval (ms): 100
    Up Delay (ms): 0
    Down Delay (ms): 0
     
    802.3ad info
    LACP rate: slow
    Min links: 0
    Aggregator selection policy (ad_select): stable
    System priority: 65535
    System MAC address: 14:18:77:58:a1:08
    Active Aggregator Info:
            Aggregator ID: 1
            Number of ports: 2
            Actor Key: 9
            Partner Key: 2
            Partner Mac Address: ec:1d:8b:de:09:80
     
    Slave Interface: em2
    MII Status: up
    Speed: 1000 Mbps
    Duplex: full
    Link Failure Count: 0
    Permanent HW addr: 14:18:77:58:a1:08
    Slave queue ID: 0
    Aggregator ID: 1
    Actor Churn State: none
    Partner Churn State: none
    Actor Churned Count: 0
    Partner Churned Count: 0
    details actor lacp pdu:
        system priority: 65535
        system mac address: 14:18:77:58:a1:08
        port key: 9
        port priority: 255
        port number: 1
        port state: 61
    details partner lacp pdu:
        system priority: 32768
        system mac address: ec:1d:8b:de:09:80
        oper key: 2
        port priority: 32768
        port number: 280
        port state: 61
     
    Slave Interface: em3
    MII Status: up
    Speed: 1000 Mbps
    Duplex: full
    Link Failure Count: 0
    Permanent HW addr: 14:18:77:58:a1:09
    Slave queue ID: 0
    Aggregator ID: 1
    Actor Churn State: none
    Partner Churn State: none
    Actor Churned Count: 0
    Partner Churned Count: 0
    details actor lacp pdu:
        system priority: 65535
        system mac address: 14:18:77:58:a1:08
        port key: 9
        port priority: 255
        port number: 2
        port state: 61
    details partner lacp pdu:
        system priority: 32768
        system mac address: ec:1d:8b:de:09:80
        oper key: 2
        port priority: 32768
        port number: 282
        port state: 61

    • This completes the process of LACP bonding on RHEL or CentOS 7 by using the NMCLI tool.

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