Network Devices and Priority

By default, all Swarm Ethernet network adapters are encapsulated into a redundant bond interface where one device is active and the remaining devices are backups. In this default mode, the first network device is the preferred device. Override this behavior by:

• Excluding a network adapter from use, such as an intelligent platform management interface (IPMI) card.

• Changing the preferred network adapter for network load management.

• Bonding multiple adapters together for increased throughput (such as NIC teaming).

To override the network adapter, configure the switch ports to the appropriate mode. Swarm supports these Linux bonding driver modes: 

• active-backup (Active-backup)

• balance-alb (Adaptive load balancing)

• 802.3ad (IEEE 802.3ad)

To override the Swarm default network device settings, edit one of the following boot configuration files:

• syslinux.cfg if the node is booting from the USB flash drive

• pxelinux.cfg if the node is booting from the network

In the configuration file, a kernel parameter named castor_net is included in the append clause. castor_net allows specifying both the bonding mode for the adapters as well as a comma-separated ordered list of the network devices Swarm can use. The first device in the list is the preferred interface used when online.

Swarm assigns device names to adapters based on a sorted list of MAC addresses. Adding network hardware can change the assignment order.

Below are some examples of assigning device names in the configuration file. The other portions of the append clause are abbreviated for clarity. Note the trailing colon after the bonding mode:

append initrd=... castor_net=active-backup:eth1,eth0 
append initrd=... castor_net=balance-alb:eth0,eth1 
append initrd=... castor_net=802.3ad:eth1,eth0 
append initrd=... castor_net=eth1,eth2 
append initrd=... castor_net=802.3ad: