I note that the Configuration Guide for ACI v4 says
Forward Error Correction (FEC) is enabled for all 100G transceivers by default. Do not use QSFP-100G-LR4-S / QSFP-100G-LR4 transceivers for multipod configuration.
Since I intend to use QSFP-100G-LR4-S optics for some of these links, is there no workaround? Why can't I just fix the FEC mode on the IPN switch ports (Nexus C9504, running 9.2(2)) and on the spine ports to rs-fec/CL91?
