Alcatel-Lucent 7450 Quality Of Service Manual page 180

Network Queue QoS Policy Command Reference
Special Cases Forwarding Class Queue on Egress Network Port or Channel — For network egress, each
Forwarding Class Queue on Ingress XMA or MDA — For network ingress, each forwarding
Parameters percent — The percent of buffers reserved from the total buffer pool space, expressed as a decimal
high-prio-only
Syntax high-prio-only percent
no high-prio-only
Context config>qos>network-queue>queue
Description The high-prio-only command allows the reservation of queue buffers for use exclusively by high
priority packets as a default condition for access buffer queues for this network queue policy.
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forwarding class is supported by an egress queue on a per network port basis. These
forwarding class-based queues are automatically created once a port or channel is placed in
the network mode. The configuration parameters for each queue come from the applied egress
network-queue policy on the network port or channel. Forwarding Class Queue on egress
channel applies only to the 7450 ESS and 7750 SR.
The cbs value is used to calculate the queue's CBS size based on the total amount of buffer
space allocated for the buffer pool on the egress network port or channel. This buffer pool size
will dynamically fluctuate based on the port or channel's egress pool size setting.
The total reserved buffers based on the total percentages can exceed 100 percent. This might
not be desirable and should be avoided as a rule of thumb. If the total percentage equals or
exceeds 100 percent of the buffer pool size, no buffers will be available in the shared portion
of the pool. Any queue exceeding its CBS size will experience a hard drop on all packets until
it drains below this threshold.
class is supported by an ingress queue per XMA or MDA. These forwarding class queues are
automatically created once a single port or channel is placed in the network mode on the
XMA/MDA and are removed once all network ports or channels are removed from the XMA/
MDA (defined as access). The configuration parameters for each queue come from the
applied ingress policy under the network context of the XMA or MDA.
The cbs value is used to calculate the queue's CBS size based on the total amount buffer space
allocated for the network ingress buffer pool on the XMA or MDA. This buffer pool will
dynamically fluctuate based on the sum of all ingress pool sizes for all network ports and
channels on the XMA or MDA.
The total reserved buffers based on the total percentages can exceed 100 percent. This might
not be desirable and should be avoided as a rule of thumb. If the total percentage equals or
exceeds 100 percent of the buffer pool size, no buffers will be available in the shared portion
of the pool. Any queue exceeding its CBS size will experience a hard drop on all packets until
it drains below this threshold.
integer. If 10 MB is the total buffers in the buffer pool, a value of 10 would reserve 1MB
(10%) of buffer space for the forwarding class queue. The value 0 specifies that no reserved
buffers are required by the queue (a minimal reserved size can be applied for scheduling
purposes).
Values
0 to 100
Quality of Service Guide