A method for performing an in-service software update in a MLAG domain. The method includes restarting the first switch using a second version of software, detecting by a second switch that the first switch is restarting and, in response to the detection, SSO. After restarting the first switch, prior to the first switch performing graceful reinsertion into the MLAG domain, setting all non-peer ports on the first switch to an error-disabled state and selecting a common MLAG protocol version supported by the first switch and the second switch and performing graceful reinsertion, which includes reestablishing a peering relationship between the first switch and the second switch using the common MLAG protocol, and after reestablishing the peering relationship, synchronizing a control plane state of the first switch with the control plane state of the second switch and setting all non-peer ports on the first switch to an active state.