Feature Overview of QoS Bandwidth Estimation
Allocating adequate bandwidth is key to ensuring the network performance
required for applications. However, allocating too much bandwidth can
be costly. The QoS Bandwidth Estimation feature in Cisco IOS software
uses Corvil Bandwidth technology to allow you, as a network manager, to
determine the bandwidth requirements to achieve user-specified quality
of service (QoS) targets for networked applications.
Corvil Bandwidth can determine the minimum bandwidth required to deliver
traffic within customer-specified QoS targets with statistical
reliability. From a network management perspective, an application's QoS
requirements are characterized with respect to its sensitivity to delay
and packet loss. Corvil Bandwidth provides a way to specify limits for
delay and packet loss, and get a tight estimate of the minimum bandwidth
essential to achieve desired application performance.
Corvil Bandwidth achieves its results by taking very short timescale
(8-millisecond) snapshots of traffic and summarizing them in traffic
descriptors that place very low overhead on the router because each
descriptor has fewer than 300 bytes. These traffic descriptors record
the exceptional events (bursts) and are input to the Corvil Bandwidth
algorithm to calculate the minimum bandwidth required to deliver the
user-specified QoS target for the observed traffic. (The QoS target is
specified in terms of sensitivity to traffic delay and packet loss. For
example, voice over IP [VoIP] traffic is very sensitive to both, whereas
e-mail file transfer is sensitive to neither.)
As a result, turning on Corvil Bandwidth in the router allows you to
obtain bandwidth values that can be used directly to configure the
existing Cisco IOS QoS mechanisms on the router to achieve the required
application performance as efficiently as possible.
Prerequisites for QoS Bandwidth Estimation
• Before using this feature,
configure a class map and a policy map using the Modular Quality of
Service (QoS) Command-Line Interface (CLI) (MQC), and specify the
appropriate match criteria.
•
This
feature requires the purchase of a Cisco IOS software feature license.
The right to use this feature is not included in the base Cisco IOS
software license for the software image.
This
feature requires the purchase of a Cisco IOS software feature license.
The right to use this feature is not included in the base Cisco IOS
software license for the software image. Restrictions for QoS Bandwidth Estimation
This feature supports policy maps that are attached to interfaces in an output direction only.
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