Indraneel,
I guess INTRAA, GTNexus are cloud portals to which ocean carriers are logged in. It usually has the schedules of ocean liners and the agreement master data between shipper and the liner. Hence for an ocean scenario, once the freight booking is created in TM, you can send this to INTRAA via TransportationBookingRequestOut interface. Carrier selection, schedule and dates can be finalized in these portals and the booking confirmation can be sent to TM.
In addition to this shipping instructions can be sent to these portals from TM, and this in turn can be sent to liners, based on which, carrier bill of lading can be created. Once the shipment is in execution these portals can send shipment status to TM. All these can be send via standard interfaces in TM.