The CMS Outer Tracker at HL-LHC will have to cope with pileup of 300 events per bunch cross-
ing and a trigger rate of up to 1 MHz. The front-end electronics readout chain consists of read-
out ASICs connected to a data concentrator ASIC featuring zero-suppression. This contribution
presents the methodology and the analysis work for the buffer sizing and exception handling fea-
turing a robust data readout synchronization, with an event loss probability lower than 0.1 % at
the highest pileup condition and a power density lower than 100 mW/cm$^2$ .