User's Manual
61
February 2007
MP-202 Telephone Adapter
8. Quality of Service (QoS)
8
Quality of Service (QoS)
8.1 Traffic
Shaping
Traffic Shaping is the solution for managing and avoiding congestion where a high speed
LAN meets limited broadband bandwidth. A user may have, for 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 provides more
sophisticated definitions, such as:
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.
8.1.1
Device Traffic Shaping
This section describes the different Traffic Shaping screens and terms, and presents the
feature’s configuration logic.
1.
On the sidebar click the QoS link and then click the tab 'Traffic Shaping'.
2.
Click the link 'New Entry'; the screen 'Add Device Traffic Shaping’ opens (refer to the
figure).
Figure
8-1: QoS - Add Device Traffic Shaping