Figure compares a manual QoS configuration task to
an AutoQoS task. A total of 34 lines have been left off the
figure so it will fit on the page.
Content
5.1 Introducing Cisco AutoQoS
5.1.2 Cisco AutoQoS Evolution Cisco AutoQoS has
evolved into two implementations: Cisco AutoQoS VoIP and Cisco
AutoQoS for the Enterprise . Cisco AutoQoS VoIP
Cisco AutoQoS VoIP offers straightforward capabilities to
automate VoIP deployments for customers who want to deploy IP
telephony but who lack the expertise or staffing to plan and
deploy IP QoS and IP services. Cisco AutoQoS VoIP is the first
release of Cisco AutoQoS and automates QoS settings for VoIP
deployments only. This feature automatically generates
interface configurations, policy maps, class maps, and access
control lists (ACLs). Cisco AutoQoS VoIP automatically employs
Cisco Network-Based Application Recognition (NBAR) to classify
voice traffic and mark it with the appropriate differentiated
services code point (DSCP) value. You can instruct Cisco
AutoQoS VoIP to rely on, or trust, the DSCP markings previously
applied to the packets. Cisco AutoQoS for the
Enterprise
Cisco AutoQoS for the Enterprise expands
its capabilities beyond VoIP and addresses the QoS requirements
of enterprise converged networks. Cisco AutoQoS for the
Enterprise adds an important step—users can observe the
applications discovered during the observation phase (Auto
Discovery) and review the QoS policy that Cisco AutoQoS for the
Enterprise suggests without deploying that policy. Cisco
AutoQoS for the Enterprise blends the design and implementation
of QoS, based on the most common enterprise scenarios, into two
major steps: - Using NBAR discovery techniques, Cisco
AutoQoS automatically discovers which applications the
enterprise network uses and generates an optimal policy. This
step employs the NBAR discovery mechanism.
- Cisco
AutoQoS then implements the generated policy.
Figure
shows the hardware and software requirements for Cisco
AutoQoS.
Content 5.1 Introducing Cisco
AutoQoS 5.1.3 Deploying Cisco AutoQoS on
Switches Deploying Cisco AutoQoS VoIP on
Switches
There are various LAN commands, depending on
the platform and operating system (Cisco IOS software versus
Cisco Catalyst operating system software). For the Cisco IOS
software-based Catalyst 2960 and Catalyst 3560 Series switches,
there are two Cisco AutoQoS configuration commands: One command
is for IP phone connections, and the other is for trusted
connections to other network devices. However, a single command
is enough to enable Cisco AutoQoS VoIP. Cisco AutoQoS VoIP in
the LAN fulfills these QoS requirements: - A single
command enables Cisco AutoQoS VoIP in a LAN, and another
command provides support for Cisco IP Phone and Cisco IP
Communicator equipment.
- Cisco AutoQoS automatically
configures QoS parameters for optimal voice performance based
upon Cisco best-practice recommendations, extensive lab
testing, and input from a broad base of Cisco Unified
Communications customer installations.
- Cisco AutoQoS
VoIP determines trust and extended trust boundary settings
automatically. A user can bypass the IP phone and connect a PC
directly to a switch, but trust is disabled when you remove the
IP phone.
- Cisco AutoQoS VoIP configures class of
service (CoS) to DSCP (to egress queue) mapping.
-
Cisco AutoQoS VoIP determines optimal priority queuing (PQ) and
weighted round robin (WRR) configuration settings for static,
dynamic-access, voice VLAN (VVLAN), and trunk ports.
To configure the QoS settings and the trusted boundary
feature for Cisco IP phones, you must enable CDP version 2 or
later on the switch port, where the IP phone is connected. If
you enable the trusted boundary feature, a syslog displays a
warning message if CDP is not enabled or if CDP is running
version 1. You need to enable CDP only for the Cisco IP phone
QoS configuration; CDP does not affect the other components of
the automatic QoS features. Figure summarizes these points.
Configuring Cisco AutoQoS on Cisco Catalyst
Switches
For Cisco IOS-based Catalyst switches, there
are two Cisco AutoQoS VoIP configuration commands. Figure shows
the command syntax. One command is for trusted connections to
other network devices, and the other is for Cisco IP phone
connections: - The auto qos voip trust interface
configuration command activates Cisco AutoQoS VoIP on a Cisco
IOS-based switch and sets the ingress interface to trust the
ingress CoS QoS marking received in the packet. It also
reconfigures the egress queues on the interface.
- The
auto qos voip cisco-phone interface configuration
command enables the trusted boundary feature. The trusted
boundary feature uses the CDP to detect the presence or absence
of a Cisco IP phone. When AutoQoS detects a Cisco IP phone, the
ingress classification on the interface is set to trust the QoS
label received in the packet. When a Cisco IP phone is absent,
AutoQoS sets the ingress classification to not trust the QoS
label in the packet. It also reconfigures the egress queues on
the interface. This command extends the trust boundary if an IP
phone is detected.
Do not use these commands if
there are previous QoS configurations on the switch. However,
you can tune the generated Cisco AutoQoS configuration
parameters (Cisco AutoQoS template) after using these
commands. Note
Both commands, in the same format,
also apply to Cisco Catalyst 4500 Series Switches. As with
Cisco Catalyst 2960 (EI) and 3560 Switches, Cisco Catalyst 4500
Series Switches do not support the Cisco SoftPhone option. When
Cisco AutoQoS VoIP is enabled on the first interface, QoS is
globally enabled (mls qos global configuration
command). Example: Cisco AutoQoS VoIP Switch
Configuration
The example in Figure shows how to enable
Cisco AutoQoS VoIP to trust the QoS marking received in
incoming packets when the switch is connected to the trusted
device (router) using the Fast Ethernet interface 0/24. The
example also shows how to enable Cisco AutoQoS VoIP to trust
the QoS marking received in incoming packets when the device
connected to Fast Ethernet interface 0/11 is detected and is a
Cisco IP phone.
Content 5.1 Introducing
Cisco AutoQoS 5.1.4 Cisco AutoQoS for the
Enterprise: Router Deployment Restrictions General
Restrictions
The VoIP feature is supported on the
following interfaces, data-link connection identifiers (DLCIs),
and permanent virtual circuits (PVCs) only: - Serial
interfaces with Point-to-Point Protocol (PPP) or High-Level
Data Link Control (HDLC)
- Frame Relay (point-to-point
subinterfaces only)
- Low-speed and high-speed ATM PVCs
in point-to-point subinterfaces
- Frame Relay-to-ATM
Interworking links
Note
Synchronous
serial interfaces are classified as low speed if the bandwidth
is less than or equal to 768 kbps. A synchronous serial
interface is classified as high speed if its bandwidth is
greater than 768 kbps. This classification is also true for ATM
PVCs. Figure summarizes these restrictions. Serial Interface
Restrictions
For a serial interface with a low-speed
link, Multilink PPP (MLP) is configured automatically. The
serial interface must have an IP address. When you configure
MLP, this IP address is removed and put on the MLP bundle. You
must meet these conditions to ensure that the traffic goes
through the low-speed link: - You must have Cisco
AutoQoS for the Enterprise configured at the both ends of the
link.
- The amount of bandwidth configured must be the
same on both ends of the link.
Frame Relay DLCI
Restrictions
Cisco AutoQoS has the following
restrictions in Frame Relay environment: - You cannot
configure Cisco AutoQoS on a Frame Relay DLCI if a map class is
attached to the DLCI.
- If a Frame Relay DLCI is
already assigned to one subinterface, you cannot configure