When enabled, frame-based accounting allows QoS policies account for the Ethernet frame overhead (for example, it accounts for the IFG (inter-frame gap) and the preamble). Typically, the IFG and preamble constitute about 20 bytes (12 + 8). The QoS meter/policer and shaper use this overhead for Ethernet ports when allocating bandwidth.
On 7210 SAS platforms, a configurable CLI command enables accounting of the frame overhead per port. This command affects the behavior of the SAP ingress FC meter, SAP ingress aggregate meter, ingress queue rate, and egress queue rate of all the SAPs configured on the port. When disabled, the SAP ingress FC meter, SAP ingress aggregate meter, ingress queue rate, and egress queue rate, along with the port egress rate, do not account for the Ethernet frame overhead. When enabled, the SAP ingress FC meter, SAP ingress aggregate meter, ingress queue rate, and egress queue rate, along with the port egress rate, account for the Ethernet frame overhead. By default, frame-based accounting is disabled for the port.
Accounting records and statistics account for frame overhead for SAPs configured on the port when FBA is enabled on the port.
On the 7210 SAS-K 2F1C2T, frame-based accounting is supported on both access ports and access-uplink ports.
On the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C, frame-based accounting is supported on network ports, hybrid ports, access ports, and access-uplink ports.