How Are Traffic Queues Defined; Which Queue Management Methods Are Supported - Dell PowerEdge M420 Configuration Manual

How Are Traffic Queues Defined?

For each queue, you can specify:
• Minimum bandwidth guarantee: A percentage of the port's maximum
negotiated bandwidth reserved for the queue.
• Scheduler type – strict/weighted:
– Strict priority scheduling gives an absolute priority, with traffic in the
highest priority queues always sent first, and traffic in the lowest
priority queues always sent last.
– Weighted scheduling requires a specification of priority for each
queue relative to the other queues, based on their minimum
bandwidth values.

Which Queue Management Methods Are Supported?

The switch supports the following methods, configurable per-interface-
queue, for determining which packets are dropped when the queue is full:
• Taildrop: Any packet forwarded to a full queue is dropped regardless of its
importance.
• Weighted Random Early Detection (WRED) drops packets selectively
based their drop precedence level. For each of four drop precedence levels
on each WRED-enabled interface queue, you can configure the following
parameters:
– Minimum Threshold: A percentage of the total queue size below
which no packets of the selected drop precedence level are dropped.
– Maximum Threshold: A percentage of the total queue size above
which all packets of the selected drop precedence level are dropped.
– Drop Probability: When the queue depth is between the minimum
and maximum thresholds, this value provides a scaling factor for
increasing the number of packets of the selected drop precedence level
that are dropped as the queue depth increases.
Configuring Class-of-Service
1129