ZyXEL Communications GS1920-48HPv2, Руководство пользователя

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Chapter 23 Queuing Method
GS1920v2 Series User’s Guide
198
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HA PTER
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Q ue uing Me tho d
23.1 Q ue uing Me tho d O ve rvie w
This chapter introduces the queuing methods supported.
Queuing is used to help solve performance degradation when there is network congestion. Use the
Q ue uing Me tho d
screen to configure queuing algorithms for outgoing traffic. See also
Prio rity Q ue ue
Assig nm e nt
in
Switc h Se tup
and
802.1p Prio rity
in
Po rt Se tup
for related information.
23.1.1 Wha t Yo u C a n Do
Use the
Q ue ue ing Me tho d
screen ( Section 23.2 on page 199 ) set priorities for the queues of the Switch.
This distributes bandwidth across the different traffic queues.
23.1.2 Wha t Yo u Ne e d to Kno w
Queuing algorithms allow switches to maintain separate queues for packets from each individual
source or flow and prevent a source from monopolizing the bandwidth.
Stric tly Prio rity Q ue uing
Strictly Priority Queuing (SPQ) services queues based on priority only. As traffic comes into the Switch,
traffic on the highest priority queue, Q7 is transmitted first. When that queue empties, traffic on the next
highest-priority queue, Q6 is transmitted until Q6 empties, and then traffic is transmitted on Q5 and so on.
If higher priority queues never empty, then traffic on lower priority queues never gets sent. SPQ does not
automatically adapt to changing network requirements.
We ig hte d Fa ir Q ue uing
Weighted Fair Queuing is used to guarantee each queue's minimum bandwidth based on its bandwidth
weight (portion) (the number you configure in the Weight field) when there is traffic congestion. WFQ is
activated only when a port has more traffic than it can handle. Queues with larger weights get more
guaranteed bandwidth than queues with smaller weights. This queuing mechanism is highly efficient in
that it divides any available bandwidth across the different traffic queues. By default, the weight for Q0
is 1, for Q1 is 2, for Q2 is 3, and so on.
We ig hte d Ro und Ro b in Sc he duling (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 a 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