Alcatel-Lucent 7950 Quality Of Service Manual page 436

Shared Queue QoS Commands
disabled through the network-queue policy assigned to the MDA for the network ingress buffer pool
or assigned to the network port for network egress buffer pools.
The resultant CBS size can be larger than the MBS. This will result in a portion of the CBS for the
queue to be unused and should be avoided.
Default
The cbs forwarding class defaults are listed in the table below:
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>shared-queue>queue
Description The high-prio-only command allows the reservation of queue buffers for use exclusively by high pri-
ority packets as a default condition for access buffer queues for this shared queue policy.
The difference between the MBS size for the queue and the high priority reserve defines the threshold
where low priority traffic will be discarded. The result is used on the queue to define a threshold
where low priority packets are discarded, leaving the rest of the default MBS size for high priority
packets only. If the current MBS for the queue is 10MBytes, a value of 5 will result in a high priority
reserve on the queue of 500KBytes. A value of 0 specifies that none of the MBS of the queue will be
reserved for high priority traffic. This does not affect RED slope operation for packets attempting to
be queued.
Modifying the current MBS for the queue through the mbs command will cause the default high-
prio-only function to be recalculated and applied to the queue. The high-prio-only command as
defined for the specific queue can be used to override the default high-prio-only setting as defined in
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Forwarding Class
Network-Control
High-1
Expedited
High-2
Low-1
Assured
Low-2
Best-Effort
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 — 100
Fowarding Class Label
nc
h1
ef
h2
l1
af
l2
be
7950 XRS Quality of Service Guide
Default CBS
3
3
1
1
3
1
3
1