I'm wondering if it's possible to configure MLAG where the primary for a given MLAG pair is a 10G port and the secondary (failover) is 1G. Some of my systems have enough 10G NIC ports for full/symmetrical 10G primary/secondary but others only have 1G NIC ports available as the secondary. I'd rather have slower failover than none at all. One big red flag is the comment that says the primary switch is chosen based on lowest MAC address ... so that alone might prevent me from being able to force the 10G switch as the primary. Just planning right now -- I purchased some Mikrotik 10G and 1G switches for an upgrade I haven't started building out yet.

I don't think this is possible. Aside from MLAG, most LACP implementations don't support links of variable speeds because it depends on equal speeds for hashing traffic.

An active/passive bond might be a better fit

That was my thought -- that LACP doesn't allow it so it won't work for MLAG which appears to be based on LACP ... even though there is no MLAG defined by LACP. I don't think I realized until now that acitve-passive is actually different? I probably need to read more here. To be clear: My main thought was only for failover and not additional bandwidth type bonding. But I want the failover to cover switch failure, which is what led me to MLAG.

Yes active/passive is not the 802.3ad LACP standard and is implemented by most operating systems as a proprietary etherchannel/bond

Okay, makes sense ... like the Linux modes I'm familiar with. I'm now guessing that Linux is the core of Mikrotik ... Is there a good step-by-step for setting this up with two switches? And the two switches would obviously have to be connected ... wondering if that connection is anything other than a standard connection like when adding a second switch for additional ports since you use the term "cross connect." Thanks for the info. This is much clearer now.