Egress SAP, subscriber, and network queues by default use drop tails within the queues and WRED slopes applied to the pools in which the queues reside to apply congestion control to the traffic in those queues. An alternative to this is to apply the WRED slopes directly to the egress queue using WRED per queue. See Table: WRED-per-queue congestion control summary .
WRED per queue is supported for SAP egress QoS policy queues (and therefore to egress SAP and subscriber queues) and for queues within an egress queue group template. There are two modes available:
Native, which is supported on FP3- and higher-based hardware
Pool-per-queue
| Inplus-profile traffic | In-profile traffic | Out-of- profile traffic | Exceed-profile traffic | WRED-queue mode | Slope usage | Comments | |
|---|---|---|---|---|---|---|---|
FP3- and higher-based queues |
Drop tail (MBS) used |
Drop tail (MBS) used |
Low slope used |
Exceed slope used |
Native |
Exceed-low |
If slope shutdown, MBS is used Highplus and high slope not used |
Pool-per-queue |
Highplus slope |
High slope |
Low slope |
Exceed slope |
Pool-per-queue |
Default |
If slope shutdown, MBS is used |
Pool/megapool |
Highplus slope |
High slope |
Low slope |
Exceed slope |
N/A |
N/A |
If slope shutdown, total pool size is used |