Red Slopes - Alcatel-Lucent 7450 Quality Of Service Manual

Slope policies define the RED slope characteristics as a percentage of pool size for the pool
on which the policy is applied.
Default buffer pools exist (logically) at the port and XMA and MDA levels. Each physical
port has two pool objects associated:
By default, each pool is associated with slope-policy default.
Access and network pools (in network mode) and access uplink pools (in access uplink mode)
are created at the port level; creation is dependent on the physical port mode (network, access)
or the mode of provisioned channel paths.
Node-level pools are used by ingress network queues and bundle access queues. A single
ingress network pool is created at the node-level for ingress network queues.
An ingress and egress access pool is created at the MDA level for all bundle access queues.
Slope policies can also be applied when using WRED per Queue, see

RED Slopes

Each buffer pool supports a high-priority RED slope and a low-priority RED slope. The high-
priority RED slope manages access to the shared portion of the buffer pool for high-priority
or in-profile packets. The low-priority RED slope manages access to the shared portion of the
buffer pool for low-priority or out-of-profile packets. In addition, egress access, network
pools, and megapools support an exceed slope which manages access to the shared portion of
the buffer pool for exceed-profile packets.
For access buffer pools, the percentage of the buffers that are to be reserved for CBS buffers
is configured by the user software (cannot be changed by user). This setting indirectly assigns
the amount of shared buffers on the pool. This is an important function that controls the
ultimate average and total shared buffer utilization value calculation used for RED slope
operation. The CBS setting can be used to dynamically maintain the buffer space on which
the RED slopes operate.
For network buffer pools, the CBS setting does not exist; instead, the configured CBS values
for each network forwarding class queue inversely defines the shared buffer size. If the total
CBS for each queue equals or exceeds 100% of the buffer pool size, the shared buffer size is
equal to 0 (zero) and a queue cannot exceed its CBS.
Quality of Service Guide
• Access ingress/egress pool
• Network egress pool
QoS Policies
WRED Per Queue.
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