FC/FCoE oversubscription ratios refer to the relationship between the bandwidth provided and the bandwidth required. Common types of oversubscription ratios include port bandwidth to uplink bandwidth (B), which measures the bandwidth available at the access layer compared to the uplink, and host bandwidth to storage bandwidth (D), which relates to the bandwidth demand from servers compared to the available storage bandwidth. https://www.ciscolive.com/c/dam/r/ciscolive/us/docs/2017/pdf/BRKDCN-1121.pdf https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/operations/n5k_fcoe_ops.html