5. Frame-Based Accounting
This section provides information to configure frame-based accounting using the command line interface.
5.1. Overview
This feature, when enabled, allows QoS policies to 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 12 + 8 = 20 bytes. The QoS policer/meter and shaper use this overhead when allocating bandwidth for Ethernet ports.
5.1.1. Frame-Based Accounting
A configurable CLI command enables accounting of the frame overhead at ingress or egress. This is a system-wide parameter that affects the behavior of the ingress meter or egress rate. When disabled, the queue rates and egress-rate do not account for the Ethernet frame overhead. By default, frame-based accounting is disabled for both ingress and egress.
 | Note: Frame-based accounting for SAP egress aggregate meters is not supported on the 7210 SAS platforms described in this document. |
5.1.2. Effects of Enabling Ingress Frame-Based Accounting on Ingress Meter Functionality
To enable system-wide consistency in configuring QoS queue and meter rate parameters, the meters used on the system ingress might need to account for Ethernet frame overhead. Access uplink ingress and service ingress meters account for Ethernet frame overhead. A configurable CLI command can enable or disable the frame overhead accounting. This is a system-wide parameter affecting the behavior of all the meters in the system.
5.1.3. Effects of Enabling Egress Frame-Based Accounting on Access Uplink Queue Functionality
If frame overhead consideration is enabled, then 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 constitutes about 12 + 8 = 20 bytes. The overhead for Ethernet ports uses this value.
A configurable CLI command enables accounting of the frame overhead. This is a system wide parameter and 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.
| Note: 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. |
5.1.4. Frame-Based Accounting and Accounting and Statistics
Accounting records and statistics do not account for frame overhead.
5.2. Basic Configurations
To enable frame-based accounting, you must perform the following:
- The frame-based-accounting command is in the *A:Dut-1> config>qos>frame-based-accounting context.
- The ingress-enable command enables frame-based-accounting for ingress metering.
- The egress-enable command enables frame-based-accounting for egress queue rates, scheduler and port level egress-rate.
The following is a sample frame-based accounting configuration output.
5.2.1. Enabling and Disabling Frame-Based Accounting
To enable frame-based-accounting for ingress, you can simply use the ingress-enable command and to enable frame-based-accounting on egress use the egress-enable command. To disable frame-based-accounting for ingress, execute the no ingress-enable command and to disable frame-based-accounting on egress, execute the no egress-enable command.
The following output displays the enabling of frame-based-accounting:
The following output displays the disabling of frame-based-accounting: