Hi Andrzej,
SN2700B does only supports 40g, not the 56GbE and below are the specification for the same.
MSN2700-BS2F Spectrum™ based 40GbE, 1U Open Ethernet Switch with MLNX-OS, 32 QSFP28
ports, 2 Power Supplies (AC), x86 CPU, Standard depth, P2C airflow, Rail Kit, RoHS6
Thanks
Khwaja