CANOGA PERKINS 9145ELB NID Software Version 4.01 - Manual (Page 140)

9145ELB NID Software User’s Manual Bandwidth Profiles
Queue size and yellow packet thresholds
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11.3.1 Shaper statistics
Shaper related statistics are the same as egress queue statistics. The following statistics are
collected per queue:
• Total classified packets (that is, packets assigned to the queue)
• Total packets dropped according to drop profile (not applicable if shaping is enabled on
the queue)
• Total queued green packets and total queued yellow packets
• Total dropped green packets and total dropped yellow packets (packets dropped due to
shaping)
For shaping purposes, yellow packets are marked with the DE bit set in the outer tag.
11.4 Queue size and yellow packet thresholds
Each egress queue has a configured frame size which indicates the number of bytes that can be
held in the queue while awaiting transmission. In this release, a new parameter, yellow packet
threshold (EBS*), is configured on each queue, expressed as a percentage. Once a queue
occupancy exceeds the specified yellow threshold, only green packets are accepted in the
queue. The yellow packets (that is, packets with DE bit set, as defined by the policer) are
dropped. For example, for a queue of a size of 1000 bytes, with a yellow threshold at 70%, yellow
frames will no longer be placed in the queue when the queue occupancy is greater than 700
bytes.
Packets accepted in the queue are sent out at CIR rate, as long as the queue occupancy is
below the yellow threshold. Once the queue occupancy is above the yellow threshold, the frames
are transmitted at EIR rate, until the queue occupancy decreases under the yellow threshold.
Frames sent under the EIR rate are marked as yellow (that is, DE bit set) regardless of the color
determined by the policer. The yellow frames marked as such by the policier are not remarked to
green by the shaper, regardless of the queue occupancy at the time of transmission.