GST on commission income under the transport sector

I am a transport commission agent. I arrange vehicles from sub-brokers or lorry owners attached to me and supply the vehicles to transporters (GTA). The transporter pays me the freight agreed. I in turn make the payment to the sub-broker or lorry owner against a cut or commission. Let's say I hired a vehicle for 25000/- from a sub-broker / lorry owner and supply to a GTA for 27000/-. The transporter pays me and I pay the sub-broker / Lorry owner. So I earn 2000/- which is my commission income. My query is will the 27000/- amount be considered my turnover or not and whether he is liable to pay GST or not if he registered under GST