This classifies what kind of traffic a specific underlying TCP connection within the FCIP link carries -- dedicated control-plane messages, data-plane storage traffic, or both combined on one connection. FCIP implementations that separate control and data onto distinct TCP connections do so to prevent control-plane signaling like keepalives from being delayed behind large data transfers, so seeing both here versus separate control and data connections tells an admin whether this particular link is using that separation. A high-performance FCIP deployment carrying heavy replication traffic might show separate TCP connections marked control and data respectively, ensuring a large data transfer never delays a critical keepalive that would otherwise ride the same connection under a both configuration.