https://www.juniper.net/documentation/en_US/junos/topics/concept/vcf-components.html
1- single point of management
2- ECMP ,
3- Plug and play for the Leaves ( discover Neighbor and number of links )
4- ISSU
5- VxLAN L2 gw
support NSSU on QFX5110 VCF in 19.3
4x Spine and 16x Leaves ( 20 nodes )
Juniper QFX5100 Overview