On ACX Series platforms running Junos EVO, the port-mirroring analyzer configuration requires unit 0 as the ingress input. This is a syntactic requirement only - mirroring is implemented in hardware at the physical interface (IFD) level, so traffic on every configured VLAN sub-unit (IFL) on that interface is mirrored.

labroot@mcar-nwha-1-re0# commit 

re0: 

[edit forwarding-options analyzer test]

 'input'

  Analyzer input can only be on .0 interfaces

error: commit failed: (validation hook evaluation failed)

Port mirroring on ACX Series running Junos OS Evolved is implemented in hardware at the IFD (physical interface) level, not at the IFL (sub-unit) level. The analyzer configuration must reference unit 0 as the ingress input, but the forwarding hardware mirrors all ingress traffic on the physical interface - regardless of which VLAN sub-unit the traffic arrives on.

labroot@host# show interfaces et-0/0/1 | display set

  set interfaces et-0/0/1 flexible-vlan-tagging

  set interfaces et-0/0/1 speed 10g

  set interfaces et-0/0/1 unit 0 vlan-id 10 <<<<<< dummy required for port-mirroring

  set interfaces et-0/0/1 unit 0 family inet address 10.10.10.1/24

  set interfaces et-0/0/1 unit 1 vlan-id 20

  set interfaces et-0/0/1 unit 1 family inet address 10.10.20.1/24

  set interfaces et-0/0/1 unit 2 vlan-id 100

  set interfaces et-0/0/1 unit 2 family inet address 10.10.100.1/24

  set interfaces et-0/0/1 unit 3 vlan-id 30

  set interfaces et-0/0/1 unit 3 family inet address 10.10.30.1/24

  set interfaces et-0/0/1 unit 4 vlan-id 40

  set interfaces et-0/0/1 unit 4 family inet address 10.10.40.1/24

  set interfaces et-0/0/1 unit 5 vlan-id 50

  set interfaces et-0/0/1 unit 5 family inet address 10.10.50.1/24

  set interfaces et-0/0/1 unit 6 vlan-id 60

  set interfaces et-0/0/1 unit 6 family inet address 10.10.60.1/24

Could capture traffic between 10.10.20.2 to 10.10.20.1