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Queuing Algorithms
Queuing algorithms allow switches to maintain separate queues for packets from each individual
source or flow and prevent a source from monopolizing the bandwidth.
Strict-Priority (SPQ)
The packets on the high priority queue are always service firstly.
Weighted round robin (WRR)
Round Robin scheduling services queues on a rotating basis and is activated only when a
port has more traffic than it can handle. A queue is given an amount of bandwidth
irrespective of the incoming traffic on that port. This queue then moves to the back of the
list. The next queue is given an equal amount of bandwidth, and then moves to the end of
the list; and so on, depending on the number of queues being used. This works in a looping
fashion until a queue is empty.
Weighted Round Robin (WRR) scheduling uses the same algorithm as round robin
scheduling, but services queues based on their priority and queue weight (the number you
configure in the queue
Weight
field) rather than a fixed amount of bandwidth. WRR is
activated only when a port has more traffic than it can handle. Queues with larger weights
get more service than queues with smaller weights. This queuing mechanism is highly
efficient in that it divides any available bandwidth across the different traffic queues and
returns to queues that have not yet emptied.
Default Settings
QoS mode
: High First (SPQ)
The mappings of the Priority to Queue are:
PRIO 0 ==> COSQ 2
PRIO 1 ==> COSQ 0
PRIO 2 ==> COSQ 1
PRIO 3 ==> COSQ 3
PRIO 4 ==> COSQ 4
PRIO 5 ==> COSQ 5
PRIO 6 ==> COSQ 6
PRIO 7 ==> COSQ 7
The DiffServ is disabled on the switch.
DSCP Priority DSCP
Priority DSCP Priority DSCP Priority
----
-------- ----
-------- ---- -------- ----
--------
00 0 01 0 02 0 03 0
04 0 05 0 06 0 07 0
08 0 09 0 10 0 11 0
12 0 13 0 14 0 15 0
16 0 17 0 18 0 19 0
20 0 21 0 22 0 23 0
24 0 25 0 26 0 27 0
28 0 29 0 30 0 31 0
