Alcatel Carrier Internetworking Solutions Omni Switch/Router - Manual (Page 830)

Introduction
Page 28-4
ToS and QoS Interaction
On the Omni Switch/Router and OmniSwitch, ToS policies may only be configured through
WAN commands. The WAN UI/CLI commands allow a higher priority of service for voice and
voice signalling data.
WAN ToS policies are supported when bridging or routing; ToS policies configured through
the QoS Manager are only supported for routing.
With the WAN ToS feature, the switch can examine an egress IP packet (either bridged or
routed) on a WAN interface and compare the value in the ToS/DSCP header with a
configured mask and value for voice data. If it does not match, the value is then compared to
the ToS value for voice signaling. (the default values correspond to compatible values for
Alcatel Voice over IP modules).
On the Omni Switch/Router or OmniSwitch, when the frame matches either the voice data or
voice signaling value the frame is forwarded to the high priority queue without any
bandwidth monitoring or restrictions.
The WAN ToS feature should be used for ToS/DSCP flows in trusted networks when no other
QoS mechanism is required, such as a voice/data converged network with private WAN
infrastructure. Typically the default WAN ToS settings are sufficient. For more information
about WAN modules and WAN ToS commands, see your switch user manual.
Use the QoS Manager instead of the WAN ToS feature if you need to give priority to other
types of traffic or if you want to classify or filter traffic. (The QoS Manager and WAN ToS
features cannot be used together.) For example, if a WAN network is not used for voice/data
convergence but prioritization is required for data traffic, use the QoS Manager to create a
rule to classify the ToS/DSCP flow with the Voice over IP (VoIP) gateway address and give
priority to the flow.