We are in the process of using for production a 7 host reef ( 18.2.2) cluster 

and we noticed lots and continuous "slow OSD heartbeats"

although there is no clients, no data and the nodes are using 2 x 25GB for Frontend and 2 x 100GB for backend

The logical culprits is the network 

we have 2 x S5850 with  MLAG and LACP

I was wondering if any of you are familiar with FS and can provide some guidance as to how to properly configured ( or troubleshoot)

Note

We are  running in a air gapped environment so cannot provide outputs/config 

but here are some pictures 

Many thanks

Steven