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Page 2 | AlliedWare Plus™ OS: Overview of QoS
z Ability to see the current state of egress queues
There are commands that enable you to see statistics relating to every egress queue on
every port.
Each of these features is discussed in much more detail later on in this document.
Contents
Introduction .............................................................................................................................................. 1
Which products and software version does this Note apply to? ................................................. 3
The process flow and methodology of the QoS system ................................................................ 3
Packet markers ................................................................................................................................. 4
Outline of the QoS processing flow ................................................................................................... 5
Initial mapping to an egress queue, based on 802.
1
p value .................................................... 5
Classification ...................................................................................................................................... 6
Premarking ......................................................................................................................................... 6
Policing ................................................................................................................................................ 7
Limiting or remarking (dropping non-conformant packets) ................................................... 7
Queue shaping .................................................................................................................................. 8
Scheduling .......................................................................................................................................... 9
Details of the component processes, and how to configure them ............................................ 10
QoS elements: policy maps, class maps, policers, matches .................................................. 10
Diagram of the overall QoS process flow ................................................................................ 11
Enabling QoS globally .................................................................................................................... 12
Initial mapping to queue based on tag ....................................................................................... 12
Classification .................................................................................................................................... 13
Premarking ....................................................................................................................................... 13
Policing .............................................................................................................................................. 16
Remarking ........................................................................................................................................ 22
Queue shaping—queue sets, RED, and tail-drop .................................................................... 23
Scheduling ........................................................................................................................................ 27
Egress bandwidth limiting .................................................................................................................... 29
Policing Examples ................................................................................................................................... 30
1
: Policing separate traffic types on separate ports ............................................................... 30
2: Policing one traffic type on combined ports ....................................................................... 32
3: Policing one traffic type on separate ports, and another traffic type on the same
ports combined ....................................................................................................................... 33
4: Policing combined traffic types on separate ports ............................................................. 35
5: Policing combined traffic types on combined ports .......................................................... 37
Fabric QoS .............................................................................................................................................. 38
Mapping the queues in the switching instances to queues in the fabric ............................ 39
Scheduling the queues within the fabric ................................................................................... 40