Hi,
Yes, I have only one reth interface (reth0) in my SRX5800 cluster and a specific vlan (vlan-id 3622) that is located in this SRX5800 cluster is also present in another SRX (SRX5600). They are connected through a L2 network.
This vlan (vlan-id 3622) has IP addresses either in the SRX5800 and in the SRX5600. When I make the MLAG between Extreme and the JuniperSRX5800, I cannot ping the IP interface of the SRX5600.
To note that this other SRX (SRX5600) has aggregated interfaces (ae) and it is connected to other Extreme switches through MLAG.
Cheers,
António