{ "sessions": {} }

Attribute	Description	Default
count	Sessions (PPPoE + IPoE)	1
max-outstanding	Max outstanding sessions	800
start-rate	Setup request rate in sessions per second	400
stop-rate	Teardown request rate in sessions per second	400
iterate-vlan-outer	Iterate on outer VLAN first	false
start-delay	Wait N seconds after all interface are resolved before starting sessions	0
autostart	Start sessions automatically	true

Per default sessions are created by iteration over inner VLAN range first and outer VLAN second. Which can be changed by iterate-vlan-outer to iterate on outer VLAN first and inner VLAN second.

Therefore the following configuration generates the sessions on VLAN (outer:inner) 1:3, 1:4, 2:3, 2:4 per default or alternative 1:3, 2:3, 1:4, 2:4 with iterate-vlan-outer enabled.

{
    "outer-vlan-min": 1,
    "outer-vlan-max": 2,
    "inner-vlan-min": 3,
    "inner-vlan-max": 4
}