2- Switch Architectures and features
Virtual Chassis 2008 10x in a ring* ( EX or QFX or mix*)
Virtual Chassis Fabric 20x with 4x Spine and 16x Leafs ( Spine: QFX5100s, Leafs: QFX3500s, QFX3600s, and EX4300s)
QFabric Node 2011 128x ( all port one hope away)
Juniper Fusion 2015 64x Satellites Device and 2x Aggregate Device , very flexible , per port join the Junos Fusion ( Agg Device and Satellites )
MC-LAG
Clos Architecture or IP Fabric ( many switches to manage!!! )