Alcatel-Lucent 7950 Quality Of Service Manual page 71

A scheduler policy represents a particular grouping of virtual schedulers that are defined in
Scheduler
Policy
specific scheduler tiers. The tiers and internal parent associations between the schedulers establish
the hierarchy among the virtual schedulers. A scheduler policy can be applied to either a multi-
service site or to a service Service Access Point (SAP). Once the policy is applied to a site or SAP,
the schedulers in the policy are instantiated on the object and are available for use by child queues
directly or indirectly associated with the object.
A tier is an organizational configuration used within a scheduler policy to define the place of
Tier
schedulers created in the policy. Three tiers are supported; Tier 1, Tier 2, and Tier 3. Schedulers
defined in Tier 2 can have parental associations with schedulers defined in Tier 1. Schedulers
defined in Tier 3 can have parental associations with schedulers defined at Tiers 1 or 2. Queues can
have parental associations with schedulers at any tier level.
A virtual scheduler, defined by a name (text string), is a logical configuration used as a parent to a
Virtual
Scheduler
group of child members that are dependent upon a common parent for bandwidth allocation. The
virtual scheduler can also be a child member to another parent virtual scheduler and receive
bandwidth from that parent to distribute to its child members.
The weight parameter defines the weight within the 'above CIR' level given to a child queue or
Weight
scheduler. When several children share the same level on a parent scheduler, the ratio of
bandwidth give to an individual child is dependent on the ratio of the weights of the active
children. A child is considered active when a portion of the offered load is above the CIR value
(also bounded by the child's maximum bandwidth defined by the child's rate parameter). The
portion of bandwidth given to each child is based on the child's weight compared to the sum of the
weights of all active children at that level. A weight of zero forces the child to receive bandwidth
only after all other children at that level have received their 'above CIR' bandwidth. When several
children share a weight of zero, all are treated equally.
Within CIR Within the CIR distribution process is the initial phase of bandwidth allocation between a parent
Distribution
scheduler and its child queues and child schedulers. The bandwidth that is available to the parent
scheduler is distributed first among the child members using each child's CIR level (to define a
strict priority for the CIR distribution), CIR weight (the ratio at a given CIR level with several
children), and the child's CIR value. A CIR value of zero or an undefined CIR level causes a child
to not receive any bandwidth during the CIR distribution phase. If the parent scheduler has any
bandwidth remaining after the 'within CIR' distribution phase, it will be distributed using the
above CIR distribution phase.
7950 XRS Quality of Service Guide
QoS Policies
Page 71