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