This counts data-plane payload packets received over the EOBC out-of-band path from the peer chassis for operations like ISSU. An admin cares because reliance on this slower path for bulk data transfer, rather than the main VSL data counters, would explain unusually long upgrade or synchronization times. For example, a software image transfer showing most of its traffic on this counter instead of the main data counter would point to the transfer happening over the much slower out-of-band channel.