Solution
CDR is clock data recovery. It's a circuit inside optical cable module which captures the data to retransmit it through the cable.
We can see the memory map of the cable's management interface of SFF-8636
from
https://members.snia.org/document/dl/26418.
Write QSFP VI and
Read QSFP VI are provided in LabVIEW to read and write to the cable's management interface. For example, writing 0x00 to address 98 will disable all TX and RX CDRs:
