Egress Port Rate Limiting; Applications - Alcatel-Lucent 7210 SAS E OS Quality Of Service Manual

Egress Port Rate Limiting

Egress port rate limiting allows the device to limit the traffic that egresses through a port to a value
less than the available link bandwidth. This feature is supported on the 7210 SAS E platform.

Applications

This feature is useful when connecting the 7210 SAS to an Ethernet-over-SDH (EoSDH) (or
microwave) network, where the network allocates predetermined bandwidth to the nodes
connecting into it, based on the transport bandwidth requirement. When connecting to such a
network it is important that the traffic sent into the SDH node does not exceed the configured
values, since the SDH network does not have QoS capabilities and buffers required to prioritize
the ingress traffic.
Egress rate attributes include:
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7210 SAS-E OS Quality of Service Guide
Allows for per port configuration of the maximum egress port rate, using the egress-rate
CLI command.
Ethernet ports configured as access, access uplink and network support this feature.
The port scheduler distributes the available maximum egress bandwidth based on the CIR/
PIR configuration parameters provisioned for the queues.
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 the egress queues associated with that port
(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.
Provides support for a burst parameter to control the amount of burst the egress port can
generate.
When ports are members of a LAG, all the ports use the same value for the egress-rate
and the max-burst parameters.
Service Egress/Ingress QoS Policies
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