When an egress queue is configured for native mode, it uses the native WRED capabilities of the forwarding plane queue. This is supported on FP3- and higher-based hardware.
Congestion control within the queue uses the low and exceed slopes from the applied slope policy together with the MBS drop tail. The queue continues to take buffers from its associated egress access or network buffer pool, on which WRED can also be enabled. This is shown in Figure: WRED queue: native mode.
To configure a native WRED queue, the wred-queue command is used under queue in a SAP egress QoS policy or egress queue group template with the mode set to native as follows:
qos
queue-group-templates
egress
queue-group <queue-group-name> create
queue <queue-id> create
wred-queue [policy <slope-policy-name>] mode native
slope-usage exceed-low
exit
exit
exit
exit
sap-egress <policy-id> create
queue <queue-id> [<queue-type>] [create]
wred-queue [policy <slope-policy-name>] mode native
slope-usage exceed-low
exit
exitCongestion control is provided by both the slope policy applied to the queue and the MBS drop tail.
The slope-usage defines the mapping of the traffic profile to the WRED slope and only exceed-low is allowed with a native mode queue. The slope mapping is shown in the following example and requires the low and exceed slopes to be no shutdown in the applied slope policy (otherwise traffic uses the MBS drop tail or a pool slope):
Out-of-profile maps to the low slope.
Exceed-profile maps to the exceed slope.
The instantaneous queue depth is used against the slopes when native mode is configured; consequently, the time-average-factor within the slope policy is ignored.
The inplus and in-profile traffic uses the MBS drop tail for congestion control (the highplus or high slopes are not used with a native mode queue).
If a queue is configured to use native mode WRED per queue on hardware earlier than FP3, the queue operates as a regular queue.
For example, the following SAP egress QoS policy is applied to SAP on an FP3- or higher-based hardware:
sap-egress 10 create
queue 1 create
wred-queue policy "slope1" mode native
slope-usage exceed-low
exit
exitThe details of both the pool and queue can then be shown using the following command:
*A:PE# show pools 1/1/1 access-egress service 1
===============================================================================
Pool Information
===============================================================================
Port : 1/1/1
Application : Acc-Egr Pool Name : default
CLI Config. Resv CBS : 30%(default)
Resv CBS Step : 0% Resv CBS Max : 0%
Amber Alarm Threshold: 0% Red Alarm Threshold : 0%
-------------------------------------------------------------------------------
Queue-Groups
-------------------------------------------------------------------------------
Queue-Group:Instance : policer-output-queues:1
-------------------------------------------------------------------------------
Utilization State Start-Avg Max-Avg Max-Prob
-------------------------------------------------------------------------------
HiPlus-Slope Down 85% 100% 80%
High-Slope Down 70% 90% 80%
Low-Slope Down 50% 75% 80%
Exceed-Slope Down 30% 55% 80%
Time Avg Factor : 7
Pool Total : 192000 KB
Pool Shared : 134400 KB Pool Resv : 57600 KB
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Current Resv CBS Provisioned Rising Falling Alarm
%age all Queues Alarm Thd Alarm Thd Color
-------------------------------------------------------------------------------
30% 0 KB NA NA Green
Pool Total In Use : 0 KB
Pool Shared In Use : 0 KB Pool Resv In Use : 0 KB
WA Shared In Use : 0 KB
HiPlus-Slope Drop Pr*: 0 Hi-Slope Drop Prob : 0
Lo-Slope Drop Prob : 0 Excd-Slope Drop Prob : 0
===============================================================================
Queue Information
===============================================================================
===============================================================================
Queue : 1->1/1/1->1
===============================================================================
FC Map : be l2 af l1 h2 ef h1 nc
Dest Tap : not-applicable Dest FP : not-applicable
Admin PIR : 10000000 Oper PIR : Max
Admin CIR : 0 Oper CIR : 0
Admin MBS : 12000 KB Oper MBS : 12000 KB
High-Plus Drop Tail : not-applicable High Drop Tail : not-applicable
Low Drop Tail : not-applicable Exceed Drop Tail : not-applicable
CBS : 0 KB Depth : 0
Slope : slope1
WRED Mode : native Slope Usage : exceed-low
-------------------------------------------------------------------------------
HighPlus Slope Information
-------------------------------------------------------------------------------
State : disabled
Start Average : 0 KB Max Average : 0 KB
Max Probability : 0 % Curr Probability : 0 %
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
High Slope Information
-------------------------------------------------------------------------------
State : disabled
Start Average : 0 KB Max Average : 0 KB
Max Probability : 0 % Curr Probability : 0 %
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Low Slope Information
-------------------------------------------------------------------------------
State : enabled
Start Average : 6960 KB Max Average : 8880 KB
Max Probability : 80 % Curr Probability : 0 %
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Exceed Slope Information
-------------------------------------------------------------------------------
State : enabled
Start Average : 4680 KB Max Average : 6600 KB
Max Probability : 80 % Curr Probability : 0 %
-------------------------------------------------------------------------------
===============================================================================
===============================================================================
===============================================================================
* indicates that the corresponding row element may have been truncated.
*A:PE#