SMC Networks TigerAccess SMC7816M - Manual (Page 372)

C
LASS OF
S
ERVICE
14-6
Selecting the Queue Mode
You can set the switch to service the queues based on a strict rule that
requires all traffic in a higher priority queue to be processed before lower
priority queues are serviced, Weighted Round-Robin (WRR) queuing that
specifies a relative weight of each queue, or a combination of strict service
for the high priority queues and weighted queueing for the remaining
queues.
Command Usage
• The switch can be set to service the port queues based on strict priority,
WRR, or a combination of strict and weighted queueing.
• Strict priority requires all traffic in a higher priority queue to be processed
before lower priority queues are serviced.
• WRR specifies a relative weight for each queue that determines the
percentage of service time the switch services each queue before moving
on to the next queue. This prevents the head-of-line blocking that can
occur with strict priority queuing.
• Hybrid mode uses strict priority on the high-priority queues and WRR
on the rest of the queues.
Command Attributes
• Strict - Services the egress queues in sequential order, transmitting all
traffic in the higher priority queues before servicing lower priority
queues.
• WRR - Weighted Round-Robin shares bandwidth at the egress ports by
using the default scheduling weights of 1, 2, 4, 6, 8, 10, 12, 14 for queues
0 through 7 respectively. (This is the default selection.)
• Hybrid - Strict priority is used for the high-priority queues and Weighted
Round-Robin for the rest of the queues. The high priority queues are
specified by setting a queue’s bandwidth to zero (see “Setting the Service
Weight for Traffic Classes” on page 14-7).