MLAG Limitations and Requirements

The MLAG feature has the following limitations:



The behavior of ExtremeXOS 30.1 has changed if locally configured IP addresses are used to determine network reachability. For details, see the ping command.

MLAG Requirements

The following table shows additional MLAG requirements that are specific to other protocols and features.

Items Impact

You must add the respective port (or LAG) that is part of an MLAG to a VLAN on both MLAG peers.

The set of configured VLANs on [Switch1:P1] must be identical to the set of VLANs configured on [Switch2:P2].

You must add the ISC to every VLAN that has an MLAG link as a member port.

VMAN:Membership The restrictions are the same as those for VLAN Membership.

You must create a Layer 3 VLAN for control communication between MLAG peers.

You cannot enable IP forwarding on this VLAN.

The ISC is exclusively used for inter-MLAG peer control traffic and should not be provisioned to carry any user data traffic. Customer data traffic however can traverse the ISC port using other user VLANs.


Although not recommended, a VMAN may be configured to carry Inter-MLAG peer traffic,

LAG:Load-Sharing Algorithm It is recommended but not required that LAGs that form an MLAG be configured to use the same algorithm.
Ports:Flooding To disable flooding on an MLAG, you must disable flooding on both ports (or LAGs) that form the MLAG.
Ports:Learning To disable learning on an MLAG, you must disable learning on both ports (or LAGs) that form the MLAG. Learning is disabled by default on ISC ports.
FDB:Static & Blackhole entries Configuration must be identical on both MLAG peers for entries that point to an MLAG port.
FDB:Limit learning Learning limits are applicable to member ports of each peer. The limit on the MLAG is the sum of the configured value on each peer.
FDB:MAC Lockdown This is supported but needs configuration on both peers. A switch can still receive checkpointed MAC addresses from its peer in the window between executing the lockdown command on both switches.

MLAG ports cannot be configured to be EAPS ring ports.

Configuration of the ISC port as an EAPS blocked port is disallowed.


You should ensure that the ISC port is never blocked by STP.

You should configure in such a way that one of the MLAG peers become root bridge and also configure MLAG peers with backup root option.

Loop protect feature should not be enabled on LAG ports on access switches. Enabling this feature on MLAG ports is acceptable.

For more information about STP and MLAG, see STP and MLAG.

VRRP VRRP must be enabled on Layer 3 VLANs that have MLAG member ports.

MLAG and ISC ports must be added as ESRP