Symptoms:
Federation DataPath is not working, Site to Site VM connectivity breaks if we put to one edge node in Maintenance mode out of 4 edge nodes which are in A/A mode in the primary site.
VM to VM ping connectivity between 2 sites was failing if one particular edge (edge4) was put in Maintenance mode.
This is a configuration issue. Initially, the customer had a single edge node configured for cross-site l2 forwarding, hence issue is seen when the edge node is put in Maintenance Mode.
Only Active /Standby Edge support for L2 E/W Interside forwarding, even if the environment has 4 edge nodes in A/A. For T0 upstream N/S communication, all 4 edge nodes in A/A mode are used.
Test the VM ping workflow between primary & secondary site in federation with a segment mapped to a T1 router had edge cluster mapped with 2 nodes(A/S), T1 was connected to a T0.
Site to Site VM ping works even if the active edge node is put in Maintenance mode, standby is still able to serve the traffic.