Qos Modes - Alcatel OmniStack LS 6248 User Manual

3
Configuring the Switch
• Default CoS — Packets arriving untagged are assigned to a default VPT, which
can be set by the user on a per port basis. Once the VPT is assigned, the packet
is treated as if it had arrived with this tag. The VPT mapping to the output queue is
based on the same user-defined 802.1p tag-based definitions.
• DSCP — The user can configure the system to use the IP DSCP of the incoming
packet to the output priority queues. The mapping of the IP DSCP to priority queue
is set on a per system basis. If this mode is active, a non-IP packet is always
classified to the best effort queue. The default mapping is shown in the following
table:
All network traffic which is not assigned a DSCP value is forwarded with Best Effort
service.
After packets are assigned to a specific queue, using the chosen classification
method various services can be applied. Scheduling for output queues can be
configured, including:
• Strict priority.
• Weighted Round Robin (WRR)
Scheduling schemes are specified per system. For each interface or queue, the
following output shaping can also be configured:
• Committed Information Rate (CIR)

QoS Modes

The device supports the following QoS modes:
• Basic QoS Mode
• Advanced QoS Mode
Note:
When moving to and from basic and advanced QoS modes, some settings may be
lost.
Basic QoS Mode
Basic Mode supports activating one of the following Trust settings:
• VLAN Priority Tag
• DiffServ Code Point
• None
In addition, a single MAC-based or IP-based ACL can be attached directly to the
interface (see Defining QoS Class Maps for more information). Only packets that
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Table 3-6. DSCP Default Mapping Table
DSCP Value
0-15
16-31
32-47
48-64
Queue Number
q1 (Lowest Priority)
q2
q3
q4