virtual chassis with shared link to non stackable switches

[Steve_Smith1]

I've got 2 x450 in a stack configuration (virtual chassis) as a core with a 2 port shared link out to one edge. The edge has been replaced with non stackable x440-10G (the 10Gb SFP+ slots need to be preserved at this time for other uses so I can't use these as stacking option) but I want to be able to trunk all the vlans from the core to both edge switches.

sharing on the core is 2 ports address based. If I configure m-lag on the 2 edge switches with an isc interconnect, would I need to change the core end to lacp based port group?

[Stephane_Grosje]

There must be a config issue.
To be sure we are in sync, as this diagram is not clear to me:
- The MLAG pair (the middle switches) requires an ISC link between them
- The ports toward the edge should be MLAG port with the same Id per edge
- If you are using LACP, the MLAG port must be LACP LAG of one port.

Can you share the following from the MLAG pari?
- show config vsm
- show mlag peer
- show mlag ports

[Steve_Smith1]

Thanks Stephane, after posting the question I set this up in lab and it appears to work as expected, which is good. 

[Stephane_Grosje]

Hi Steve,

you're speaking of one edge, then of two edge. If this is two edge switches, you can have a LAG from a stack to an MLAG pair (running EXOS 15.3.1 at least on the MLAG side if you want LACP).

You are not forced to configure LACP, but I would recommend it if possible.

If this is x440, I would also recommend using 15.4.2 with LACP. As a best practice, manually configure the MLAG-LACP value on both MLAG peers.