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Chapter 50 Queuing Commands
Ethernet Switch CLI Reference Guide
186
• Weighted Fair Queuing (WFQ)- guarantees each queue's minimum bandwidth based on
its bandwidth weight (portion) 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. Guaranteed
bandwidth is calculated as follows:
For example, using the default setting, Q0 on Port 1 gets a guaranteed bandwidth of:
• Weighted Round Robin Scheduling (WRR) - 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 based on the queue weight value. 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.
• Hybrid Mode: WRR & SPQ or WFQ & SPQ - some switch models allow you to
configure higher priority queues to use SPQ and use WRR or WFQ for the lower level
queues.
50.2 Command Summary: Port by Port Configuration
The following section lists the commands for this feature.
Queue Weight x Port Speed
Total Queue Weight
1 x 100 Mbps = 3 Mbps
1+2+3+4+5+6+7+8
Table 105 Queuing Command Summary
COMMAND DESCRIPTION M P
queue priority <0-7> level <0-7> Sets the IEEE 802.1p priority level-to-physical queue
mapping.
priority <0-7>: IEEE 802.1p defines up to eight separate
traffic types by inserting a tag into a MAC-layer frame that
contains bits to define class of service. Frames without an
explicit priority tag are given the default priority of the ingress
port.
level <0-7>: The Switch has up to 8 physical queues that
you can map to the 8 priority levels. On the Switch, traffic
assigned to higher index queues gets through faster while
traffic in lower index queues is dropped if the network is
congested.
Note: Some models only support 4 queues.
C13
interface port-channel <port-
list>
Enters subcommand mode for configuring the specified ports. C 13
spq Sets the switch to use Strictly Priority Queuing (SPQ) on the
specified ports.
C13