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BCM 4.0 Networking Configuration Guide
Chapter 71
Configuring QoS (Quality of Service) Queuing
Outbound traffic queuing is configured on a per-interface basis. The BCM queuing strategy
follows the Nortel recommended model for seven traffic queue classes.
The premium service class (queue 1) uses a Strict Priority scheduler. This class is shaped so that
other classes do not get starved. The shaping of the premium service class is based on a percentage
(from 0% to 90%) of the available bandwidth of the interface. The unused bandwidth of the
interface is distributed across the other service classes. Therefore, the other service classes get a
minimum of 10% of the total bandwidth of the interface and a maximum of up to 100%.
Service classes (queue 2 to 7) other than premium use a simpler variant of Weighted Fair Queuing
(WFQ) called Hierarchical Token Buckets (HTB). The scheduler allows each service class to use a
guaranteed minimum traffic rate, and allows unused bandwidth of other classes in the HTB
scheduler to be redistributed to other classes.
The guaranteed bandwidth percentage value for service classes (queue 2 to 7) other than premium
is based on the remaining unused bandwidth portion of the premium service class. So the sum of
percentage values for the queue 2 to 7 must be equal to 100%.
The excess bandwidth percentage value applies to service classes other than premium. It must be
set to a value greater or equal to guaranteed bandwidth, and can be set up to 100% per class. This
value is used for traffic shaping on a per class basis.
Queuing
Refer to the following procedures:
• To configure QoS Queuing by Interface
• To modify Queue Settings
Configuring QoS Queuing
To configure QoS Queuing by Interface
1 Click Configuration > Data Services > QoS Queuing > Interfaces.
2 Click the interface you want to configure. For example: LAN1.
The details panel appears. See Figure 218.
3 Configure the settings according to Table 28.
Note: Double click the Configured Link Speed (kbps) box to edit.
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