How to connect ASR9000 to NCS2000, and add to CTC

Hi,

I work for a research lab, and we have a couple of NCS2006 switches and two ASR9904 routers. We would like to transmit between the routers through the switches.  I am struggling to add the ASR9000 to CTC; The documentation says that a direct connection (aside from the fiber connections) between the asr9000 and ncs2000 is required in order to setup LMP or an optical channel (https://www.cisco.com/c/en/us/td/docs/optical/15000r10_0/ncs/network_config/guide/b_ncs_network_configuration/b_ncs_network_configuration_chapter_01110.html#ID1484).

I don't understand what ports need to be connected between the NCS2000 and the ASR9000? I have tried the management port on the ASR9000 and the ethernet port on the TNC card. Any clues here would be appreciated