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DISCUS™ Multiplay Wireless VoIP AG
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OGU 930500105-A1
Quality of Service Section
example, a 100 Mbps Ethernet LAN with a 100 Mbps WAN interface router. The
router may communicate with the ISP using a modem with a bandwidth of
2Mbps. This typical configuration makes the modem, having no QoS module,
the bottleneck. The router sends traffic as fast as it is received, while its well-
designed QoS algorithms are left unused. Traffic shaping limits the bandwidth of
the router, artificially forcing the router to be the bottleneck.
A traffic shaper is essentially a regulated queue that accepts uneven and/or
bursty flows of packets and transmits them in a steady, predictable stream so
that the network is not overwhelmed with traffic.
While Traffic Priority allows basic prioritization of packets, Traffic Shaping pro-
vides more sophisticated definitions. Such are:
Bandwidth limit for each device
Bandwidth limit for classes of rules
Prioritization policy
TCP serialization on a device
Additionally, you can define QoS traffic shaping rules for a default device. These
rules will be used on a device that has no definitions of its own. This enables the
definition of QoS rules on Default WAN, for example, and their maintenance
even if the PPP or bridge device over the WAN is removed.
FIGURE 3.
Traffic Shaping Panel
DSCP SETTINGS
In order to understand what is Differentiated Services Code Point (DSCP), one
must first be familiarized with the Differentiated Services model.
Differentiated Services (Diffserv) is a Class of Service (CoS) model that
enhances best-effort Internet services by differentiating traffic by users, service
requirements and other criteria. Packets are specifically marked, allowing net-
work nodes to provide different levels of service, as appropriate for voice calls,
video playback or other delay-sensitive applications, via priority queuing or
bandwidth allocation, or by choosing dedicated routes for specific traffic flows.
Page 92 / 149
DISCUS™ Multiplay Wireless VoIP AG
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Quality of Service Section
Diffserv defines a field in IP packet headers referred to as DSCP. Hosts or rout-
ers passing traffic to a Diffserv-enabled network will typically mark each trans-
mitted packet with an appropriate DSCP. The DSCP markings are used by
Diffserv network routers to appropriately classify packets and to apply particular
queue handling or scheduling behavior.
DISCUS™ Multiplay Wireless VoIP AG provides a table of predefined DSCP
values, which are mapped to 802.1p priority marking method. You can edit or
delete any of the existing DSCP setting, as well as add new entries.
1.
Click 'DSCP Settings' under the QoS tab in the 'Services' screen. The follow-
ing screen will appear
2.
To edit an existing entry, click its Edit action icon. To add a new entry, click
the 'New Entry' link. In both cases, the 'Edit DSCP Settings' screen will
appear.
3.
Configure the following fields: DSCP Value (hex) Enter a hexadecimal num-
ber that will serve as the DSCP value. 802.1p Priority Select a 802.1p priority
level from the combo-box (each priority level is mapped to low/medium/high
priority).
4.
Click 'OK' to save the settings.
FIGURE 4.
DSCP Settings Panel
Page 93 / 149
DISCUS™ Multiplay Wireless VoIP AG
(C) (2006) Pirelli Broadband Solutions S.p.A. All Rights Reserved. Proprietary Use Pursuant to Cover Page Instructions.
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OGU 930500105-A1
Quality of Service Section
802.1P SETTINGS
The IEEE 802.1p priority marking method is a standard for prioritizing network
traffic at the data link/Mac sub-layer. 802.1p traffic is simply classified and sent
to the destination, with no bandwidth reservations established.
The 802.1p header includes a 3-bit prioritization field, which allows packets to
be grouped into eight levels of priority. DISCUS™ Multiplay Wireless VoIP AG
maps these eight levels to three main priorities: high, medium and low. By
default, values six and seven are mapped to high priority, which may be
assigned to network-critical traffic. Values four and five are mapped to medium
priority, which may be applied to delay-sensitive applications, such as interactive
video and voice. Values three to zero are mapped to low priority, which may
range from controlled-load applications down to “loss eligible” traffic. The zero
value is normally used for best-effort traffic. It is the default value for traffic with
unassigned priority.
1.
Click '802.1p Settings' under the QoS tab in the 'Services' screen. The fol-
lowing screen will appear
2.
The eight 802.1p values are pre-configured with the three priority levels:
high, medium and low. You can change these levels for each of the eight val-
ues in their respective combo-box.
3.
Click 'OK' to save the settings.
FIGURE 5.
802.1p Settings Panel
CLASS STATISTICS
DISCUS™ Multiplay Wireless VoIP AG provides you with accurate, real-time
information on the traffic moving through your defined device classes. For exam-
ple, the amount of packets sent, dropped or delayed, are just a few of the
parameters that you can monitor per each shaping class.
Page 94 / 149
DISCUS™ Multiplay Wireless VoIP AG
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Quality of Service Section
To view your class statistics, click 'Class Statistics' under the QoS tab in the
'Services' screen. The following screen will appear. Note that class statistics will
only be available after defining at least one class (otherwise the screen will not
present any information).
FIGURE 6.
Class Statistics Panel
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Advanced Section
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OGU 930500105-A1
Advanced
Section
This chapter will describe the
Advanced Section
accessible from
the
Home Page
of the
DISCUS™ Multiplay Wireless VoIP AG
.
The Advanced panel collects many functionalities from the operating
and configuration point of view. This chapter will describe one by one
all icons and related features as shown in the following screen shot.
Be aware that any configuration changes could compromise your connectivity.

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