Information Technology Reference
In-Depth Information
Provides configuration consistency:
Using a single-command QoS template on
each device ensures that all the devices use a similar QoS configuration that is not as
prone to forgotten commands or mistypes.
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Reduces deployment cost:
It takes some time and training to get fully up to speed
on everything QoS has to offer.
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Allows manual tuning:
You can manually adjust and tune the template-based con-
figuration deployed by AutoQoS to fit your specific network QoS requirements.
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Before you can deploy AutoQoS on your network, you must first establish the trust
boundary for your voice traffic. However, to understand the concept of a trust boundary,
you must first have a basic understanding of QoS markings. As a device sends traffic, that
traffic might or might not have QoS markings attached to it. These markings might or
might not be trustworthy. For example, a Cisco IP phone marks all of its traffic with an
extremely high priority. In this case, the markings are trustworthy because the audio traf-
fic from the phone does indeed need high-priority service. However, a technology-savvy
user might configure a computer to mark traffic from it with the same high-priority mark-
ing as the voice traffic. In this case, the marking is not trustworthy.
Now, we can jump back to the concept of a trust boundary. The trust boundary is the
point of the network where you begin trusting that the network traffic is accurately iden-
tified with the correct QoS marking. Depending on the capabilities of the devices on your
network, you can you can begin applying QoS markings close to the user devices, as
shown in Figure 6-20.
Endpoints
Access
Distribution
Core
WAN Agg.
1
Si
Si
2
3
Si
Si
Trust Boundary
Figure 6-20
Possible QoS Trust Boundaries
Cisco IP phones have the ability to mark their own traffic as high priority and strip any
high-priority markings from traffic sent by the attached PC. If you are using the Cisco IP
phone to mark traffic, you have extended the trust boundary to point 1 shown in Figure
6-20. This is the ideal trust point because it distributes the QoS marking process to many
