Configuring Class-of-Service 1129How Are Traffic Queues Defined?For each queue, you can specify:• Minimum bandwidth guarantee: A percentage of the port’s maximumnegotiated bandwidth reserved for the queue.• Scheduler type – strict/weighted:– Strict priority scheduling gives an absolute priority, with traffic in thehighest priority queues always sent first, and traffic in the lowestpriority queues always sent last.– Weighted scheduling requires a specification of priority for eachqueue relative to the other queues, based on their minimumbandwidth 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 itsimportance.• Weighted Random Early Detection (WRED) drops packets selectivelybased their drop precedence level. For each of four drop precedence levelson each WRED-enabled interface queue, you can configure the followingparameters:– Minimum Threshold: A percentage of the total queue size belowwhich no packets of the selected drop precedence level are dropped.– Maximum Threshold: A percentage of the total queue size abovewhich all packets of the selected drop precedence level are dropped.– Drop Probability: When the queue depth is between the minimumand maximum thresholds, this value provides a scaling factor forincreasing the number of packets of the selected drop precedence levelthat are dropped as the queue depth increases.
