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Network port bonding modes supported under Swarm (as supported by the Linux kernel) are:
active-backup (bonding mode 1)
balance-alb (bonding mode 6)
802.3ad (bonding mode 4)
Bonding mode 6 (balance-alb) is supported when using a single peer switch. If the requirement is calls for use of multiple switch chassis to provide switch layer redundancy, configure Swarm to use either bonding mode 1 (active-backup) or, if multi-chassis switch link aggregation (MLAG) is in use, bonding mode 4 (802.3ad).
Bonding mode 1 (active-backup) is advised for “out of the box” multi-chassis link aggregation switch and MLAG configurations, whereas bonding mode 4 (802.3ad) needs additional configuration on the switch side to function. Since failover and traffic balancing with link aggregation (using multiple switch chassis) are MLAG is proprietary to switch vendors, it is necessary to review switch capability to determine the appropriate bonding mode for multi-chassis link aggregation MLAG (i.e., bonding mode 1 or 4).
Swarm bonds the NICs NIC ports it detects and uses a single IP address for the bond definition. Multiport Note that multiport network cards (two or more ports per card) are necessary when considering failover for the aren’t considered fully redundant when used in Swarm storage hosts. Multiport NICs experience common failure modes which can disconnect a Swarm host completely. A true 'active-active' design includes the use of separate NICs in the storage hosts to meet that requirement.
PXE boot in MLAG configuration
The PXE passthrough modes are behavior is very important in either an L2 or L3 MLAG configuration. Getting Configuring nodes to the for network (PXE) boot when 802.3ad and MLAG are in place is a major pain point can prove difficult to use for such deploymentsnetwork configurations. None of them behave the same way either, therefore, Vendor implementation of PXE passthrough for MLAG can behave inconsistently, therefore active-backup bonding mode is strongly advised to for use in this scenario.