The physical management port on the back of your switch is called em0 on a QFX or EX4600 or me0 on an EX3200, 3300, 3400, 4200 or 4300.
The port is only for out-of-band management meaning you cannot reach it from any of the front-facing interfaces, nor assign it to any VLANs etc.
When you have multiple switches joined together in a virtual-chassis, all me/em interfaces are represented by a single virtual interface called vme (virtual me) - the IP address assigned to vme then floats between and is reachable via all connected me0/em0 interfaces, regardless of which device is the current Master routing-engine.
To manage the switch in-band, you will need to configure an L3 interface on the VLAN that all your ports are connected to.
Given your software version is 15.1X53, I'm assuming you must be running either an EX2300 or an EX3400 in which case you'll need to do the following:
# Assign an IP address to an interface
set interfaces irb unit 1 family inet address 10.2.5.1/24
# Assuming you are using a factory default config, bind the above IRB to the default VLAN
set vlans default vlan-id 1
set vlans default l3-interface irb.1
# Enable https web-management on irb.1
set system services web-management https system-generated-certificate
set system services web-management https interface irb.1
Hope this helps!
Ben Dale JNCIP-ENT, JNCIP-SP, JNCIP-DC, JNCIE-SEC #63 Juniper Ambassador Follow me @labelswitcher