In the multi-core era, on-chip communication networks are key to system correctness and performance. To deal with their growing complexity, micro-architectural models capture the intent of architects and provide means for formal analysis. However, the analysis of such micro-architectural models is restricted to non-scalable and/or very specific approaches. We present a novel scalable approach to support the symbolic channel type inference of large micro-architectural models described in the xMAS language proposed by Intel. We define an algorithm that computes all possible messages that can occur in a communication channel, treating their payload symbolically. These results can be used for further analysis such as verifying absence of misrouting, deriving inductive invariants and deadlock detection. We illustrate our approach on a Spidergon network developed at STMicroelectronics.