If frame overhead consideration is enabled, the queue scheduler accounts for the Ethernet frame overhead. The maximum egress bandwidth accounts for the Ethernet frame overhead (it accounts for the IFG (inter-frame gap) and the preamble). Typically, the IFG and preamble constitute about 20 bytes (12 + 8). The overhead for Ethernet ports uses this value.
A configurable CLI command enables accounting of the frame overhead. This is a system-wide command that affects the behavior of all egress queues (when frame-based accounting is enabled on egress port, the associated queues also account for frame overhead implicitly). When disabled, the port egress-rate command does not account for the Ethernet frame overhead.
Frame-based accounting does not affect the SAP egress aggregate rate command on 7210 SAS-D and 7210 SAS-Dxp. In other words, the SAP egress aggregate command does not account for the Ethernet frame overhead regardless of whether egress frame-based accounting is enabled or disabled.