It is recommended that Check Point sync interface has a second interface configured using the redundancy interface feature of XOS:circuit sync
ip 192.168.255.1/24 192.168.255.255 increment-per-vap 192.168.255.2
interface ethernet 1/16
interface ethernet 2/16
redundancy-interface master ethernet 1/16 backup ethernet 2/16 mac-usage master
It is recommended NOT to use group-interface (LACP) for Check Point synchronization. Check Point synchronization traffic mainly uses only 2 IP addresses - the source 0.0.0.0 and the synchronization network broadcast address as the destination (192.168.255.255 in the above example). This traffic is considered a single flow and as such cannot be distributed over multiple physical links. It must be transmitted over a single interface and there is no benefit in using LACP.
When LACP is configured for sync, there is even a potential performance degradation issue if the neighbor switch selects another link in the bundle to transmit the sync traffic than X-series. Such scenario leads to flow reclassification on the NPM and may cause sync issues on the cluster members.