VC for EX3400
For uplink:  both QSFP+ ( 40G ) or SFP+ ( 10G ) can be used
SPF, SPF+, QSPF, QSFP+, SFP28, QSFP28 and DAC
Virtual Chassis
You can interconnect a maximum of 10 EX3400 switches to form a Virtual Chassis. You can operate these interconnected switches as a single, logical device with a single IP address.
You can use the following ports to interconnect an EX3400 switch in a Virtual Chassis:
QSFP+ ports configured as VCPs by using QSFP+ transceivers
- NOTE
You cannot form a Virtual Chassis by using SFP transceivers.
Uplink ports on the front panel configured as VCPs by using SFP+ transceivers
By default, the QSFP+ ports are configured as VCPs.