Overview
Page 106 7210 SAS D, E, K OS Quality of Service Guide
Overview
This feature when enabled let 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 constitutes about 12 + 8 = 20 bytes. The overhead for Ethernet ports uses this value.
Frame Based Accounting on 7210 SAS-E and 7210 SAS-D
On 7210 SAS-D and 7210 SAS-E, a configurable CLI command enables accounting of the frame
overhead at ingress or egress. This is a system wide parameter and 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.
Effects of Enabling Ingress Frame Based Accounting on Ingress Meter
Functionality on 7210 SAS-E and 7210 SAS-D
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.
Effects of Enabling Egress Frame Based Accounting on Access Uplink
Queue Functionality on 7210 SAS-E and 7210 SAS-D
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 egress-rate command does not account for the Ethernet frame overhead.
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