how to configure NIC Teaming as Active Backup (Failover)

The Linux NIC teaming driver provides a method for aggregating multiple network interfaces into a single “Team” interface. The behavior of the team interfaces depends upon the runner configuration. Generally teaming supports below methods.

NIC Teaming will support

1. Round robin
2. Load balancing
3. Fail-over
4. Broadcast

Naming convention of Red Hat Enterprise Linux as, On board LAN card naming em0, em1…..etc.  Additional LAN card naming if it is a 4 port NIC card p1p1, p1p2, p1p3 and p1p4 (p1 = Slot1 p1-4=Port)

The key reasons why you might want to use teaming rather than bonding are

• Teaming has a small kernel module which implements fast handling of packets flowing through your teamed interfaces
• support for IPv6 (NS/NA) link monitoring
• Capable of working with D-Bus and Unix Domain Sockets (the default)
• It provides an extensible and scale-able solution for your teaming requirements
• load balancing for LACP support
• It makes use of Network Manager and its associates tools (the modern way) to manage your network connections

This article will provide a guide to configure NIC teaming in RHEL7.

NIC Teaming as Active Backup will provide you redundancy in case of any one of NIC is failed still end user can access services from server. We also call it has Fail-Over mechanism.

Required two NIC cards to configure teaming.

Devices status as mentioned below

[root@TeamQT ~]# nmcli connection show

NAME  UUID  TYPE  DEVICE

[root@ TeamQT ~]# nmcli device status

DEVICE  TYPE      STATE         CONNECTION

ens33   ethernet  disconnected  --         

ens36   ethernet  disconnected  --6

Creating teaming virtual interface

First we will create an master virtual teaming interface the we have to add other NIC cards as a slaves to teaming master. nmcli is the utility we have to use.

[root@ TeamQT ~]# nmcli connection add type team con-name team0 ifname team0 config '{"runner": {"name": "activebackup"}}'

Connection 'team0' (28a9e70b-8a8f-4354-a4ec-5cfac6577589) successfully added.

[root@ TeamQT ~]# nmcli connection show

NAME   UUID                                  TYPE  DEVICE

team0  28a9e70b-8a8f-4354-a4ec-5cfac6577589  team  team0

Provide IP address to team0 virtual interface

Now we have to configure an IP address, Gateway and DNS to team0 interface to communicate and add slave interface to team0

[root@ TeamQT ~]# nmcli connection modify team0 ipv4.addresses 192.168.4.50/24 ipv4.gateway 192.168.4.2 ipv4.dns 8.8.8.8 connection.autoconnect yes ipv4.method manual

Add slave interfaces to Master team interface

[root@ TeamQT ~]# nmcli connection add type team-slave con-name team0-port1 ifname ens33 master team0

Connection 'team0-port1' (8ca9c28b-bbbc-458f-94fa-56b2f607864f) successfully added.

[root@ TeamQT ~]# nmcli connection add type team-slave con-name team0-port2 ifname ens36 master team0

Connection 'team0-port2' (6e57d69e-44d3-4d12-8e6d-dc6e70189800) successfully added

team0 master interface is created and added slave interfaces to master.

Verifying Master and Slave interfaces

[root@ TeamQT ~]# nmcli connection show

NAME         UUID                                  TYPE            DEVICE

team0-port2  6e57d69e-44d3-4d12-8e6d-dc6e70189800  802-3-ethernet  ens36  

team0-port1  8ca9c28b-bbbc-458f-94fa-56b2f607864f  802-3-ethernet  ens33  

team0        28a9e70b-8a8f-4354-a4ec-5cfac6577589  team            team0  

[root@ TeamQT ~]# nmcli device status

DEVICE  TYPE      STATE         CONNECTION  

ens33   ethernet  connected     team0-port1

ens36   ethernet  connected     team0-port2

team0   team      connected     team0

Activate teaming interface

[root@ TeamQT ~]# nmcli connection down team0

Connection 'team0' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/0)

[root@ TeamQT ~]# nmcli connection up team0

Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/4)

Check functionality of Active-Backup Teaming

We can check active and backup teaming functionality using below command

[root@ TeamQT ~]# teamdctl team0 state

setup:

  runner: activebackup

ports:

  ens33

    link watches:

      link summary: up

      instance[link_watch_0]:

        name: ethtool

        link: up

  ens36

    link watches:

      link summary: up

      instance[link_watch_0]:

        name: ethtool

        link: up

runner:

  active port: ens33

as shown above active port is ens33. Now bring down the ens33 and see

[root@ TeamQT ~]# nmcli device disconnect ens33

Device 'ens33' successfully disconnected.

[root@ TeamQT ~]# teamdctl team0 state

setup:

  runner: activebackup

ports:

  ens36

    link watches:

      link summary: up

      instance[link_watch_0]:

        name: ethtool

        link: up

runner:

  active port: ens36

as soon as we disconnect / bring down one NIC card other backup NIC will activate automatically with in Milli seconds.