You should really create a new post for this separate enquiry... Leaving that aside - you use the term 'aggregate'; MX does not support link aggregation (802.3ad / LACP or similar). With MX you provide a separate WAN (Internet) uplink to each of WAN1 and WAN2 ports and the MX can make use of both links simultaneously, by allocating different sessions to different links, based upon preference and performance criteria you configure. so; don't configure any link aggregation on your switches, for connection to the MXs. Each of your MXs should be connected to both switches, on the LAN side, for resilience (your diagram shows only one such link per MX). Note however that MX does not participate in spanning tree, but will forward STP BPDUs, to allow your switches to resolve the physical loops that will create. So; configure STP on the switches to match the desired topology (e.g. bridge priority). Provided you do this properly and use different VLANs for WAN1, WAN2 and LAN-side VLANs, you should not get into STP-related problems.
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