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Command Reference Guide
regarding consumption of bandwidth by traffic, traffic can burst up to the maximum interface rate when
the output queue is not in a congested state. Qos maps are constantly classifying traffic when they are
active on an interface, but some of their actions depend on the state of the output queue. When
congestion is present, policies defined with the bandwidth command will be limited to the minimum
value specified, with excess traffic being queued. During a congested state, policies defined with the
priority command will be limited to the maximum value specified, with excess traffic being dropped.
Policies defined with the shape or set commands are always enforced regardless of congestion.
When the configured QoS map is applied to a physical interface, AOS displays bandwidth information
for the map and the physical interface. For example, if the Frame Relay interface (fr 1) has been
connected to the E1 interface (e1 1/1) using the cross-connect command, applying the QoS map
(MyMapA) to the Frame Relay interface (fr 1) produces the following status message:
2005.08.09 07:28:22 QOS.INTERFACE QOS policy "MyMapA" requires 1288 kbps of bandwidth
and 1488 kbps is now available for interface fr 1 -> the QOS policy for this port has been forced
ACTIVE.
This status message displays the total of the bandwidths specified in the QoS map (1288 kbps) and
the available interface bandwidth using the total line rate configured on the interface (1488 kbps).
3. Up to eight class-based entries (bandwidth commands) can be configured in a particular QoS map
set.
4. Within a QoS map entry, CBWFQ bandwidth and low latency priority actions are mutually exclusive.
However, bandwidth and priority actions may be applied to different entries in the same QoS map.
Determining Bandwidth Entries
When possible, use the bandwidth <value> command to specify an absolute amount of
bandwidth (in kbps) for the traffic class.
When determining the percent <value> entry, use the following formula:
where
Bandwidth
Line Rate
For example, to specify 76.8 kbps of data on an interface with a total of 512 kbps of available bandwidth,
and reserving 5 percent of the bandwidth for best effort, routing, and L2 protocol traffic
(max-reserved-bandwidth = 95) enter the following commands:
(config-qos-map)#bandwidth percent 15
(config)#interface ethernet 0/1
(config-eth 0/1)#max-reserved-bandwidth 95
60000CRG0-35E
Bandwidth
Line Rate
Specifies the minimum amount of bandwidth needed for the traffic (in kbps).
Specifies the total data rate configured on the interface (for example,
8 DS0s (64 kbps per DS0) on a T1 equals a line rate of 512 kbps).
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Quality of Service Map Command Set
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