Enterprise QoS Solution Reference Network Design Guide

Chapter 2 Campus QoS Design
Version 3.3
The logic of these policers is shown in Figure 2-8.
Enterprise QoS Solution Reference Network Design Guide
QoS Design Overview
Figure 2-8 Conditionally-Trusted Endpoint Policing—IP Phone + PC + Scavenger (Basic) Model
Start
VVLAN +
DSCP EF
Conditionally-Trusted IP Phone + PC with Scavenger-Class QoS (Advanced) Model
No
VVLAN +
DSCP AF31 or
CS3
No
VVLAN
ANY
No
DVLAN
ANY
Yes
Yes
Yes
Yes
128 kbps
32 kbps
Building on the previous model, you can add additional marking and policing for PC-based
video-conferencing and multiple levels of data applications.
Desktop videoconferencing applications use the same UDP port range by default as does Cisco
SoftPhone. If the UDP ports used by the desktop videoconferencing application can be explicitly defined
within the application, as with SoftPhone, then you can use two policers: one for IP/VC and another for
SoftPhone. Otherwise, a single policer covering the UDP port range of 16384–32767 is required, which
would be provisioned for the worst-case scenario of legitimate traffic. In this case, this is the
videoconferencing application’s requirement of 500 kbps (for a 384 kbps desktop IP/VC application), as
compared to the SoftPhone requirement of 128 kbps (or 320 kbps for G.722 codecs).
Note Policer thresholds should be set according to the video application’s requirements. Some
interactive-video applications may have higher bandwidth requirements for their codecs; for example
Cisco Video Telephony (VT) Advantage includes a proprietary codec that requires 7 Mbps of bandwidth.
You can add additional data VLAN policers to meter Mission-Critical Data, Transactional Data and Bulk
Data flows. Each of these classes can be policed on ingress to the switch port to an in-profile amount,
such as 5 percent each.
Note Since Mission-Critical and Transactional Data applications are interactive foreground applications
requiring user input, it is highly unlikely that both of these types of applications will be simultaneously
generating 5 Mbps each from a client PC. However, in the rare case that they are, these flows will be
policed further by any per-user microflow policing policies that may be deployed on distribution layer
Catalyst 6500 Supervisor 720s (PFC3s), as is detailed later in this chapter.
No
No
32 kbps
No
5 Mbps
No
Yes
Yes
Yes
Yes
Trust and Transmit
Drop
Re-Mark to DSCP CS3
and Transmit
Re-Mark to DSCP CS1
and Transmit
Re-Mark to DSCP 0
and Transmit
Re-Mark to DSCP CS1
and Transmit
Re-Mark to DSCP 0
and Transmit
Re-Mark to DSCP CS1
and Transmit
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