Flow Aware Qos Key Terms - Cisco ASR 9000 Series Configuration Manual

Flow Aware QoS Key Terms

The Flow aware QoS feature enables QoS actions to be applied at a flow level. The flows are detected or
learnt dynamically on a per-class, per-interface, per-direction level and the QoS action or decisions are applied
on a per-flow basis guided by a QoS policy applied on the interface. The framework also provides an option
to enforce admission control on the incoming traffic to preemptively prevent congestion.
The Flow aware QoS feature suite provides:
• User-defined flow definition—You can define a flow from a flexible choice of flow tuples (srcip, dstip,
• Configurable flow bandwidth to decide how many video flows to allow—You can configure the flow
• Redirection of non-admitted flows to default queue—You can redirect all the best-effort delivery traffic
• Configurable flow entry idle-timeout to tune as per use case or traffic profile— There are configurable
Flow Aware QoS Key Terms
This section lists the key terms of the Flow Aware QoS feature:
• Flow—A specific traffic pattern of the packet identified by unique source IP address (src-ip) or destination
• Flow Tuple—The individual fields that define a flow is known as flow tuple.
• Flow Mask—A list of flow tuples defining a unique flow on a per-class basis is called as a flow mask.
• Flow Table—A table of flow records that are recorded as per the flow mask is a flow table. It is also
• Flow Age—The expiry time set in the flow cache to purge out stale flow records so that the new flows
• Flow Action—The QoS action that requires per-flow resource allocation is known as flow action.
• Micro-Flow policer—A QoS policer acting on a single traffic flow is known as micro-flow policer.
• Video CAC—The call admission control (CAC) functionality customized for video streams with
• CAC Reject—A CAC action variant in which packets from all unadmitted flows are dropped.
• CAC Redirect—A CAC action variant in which packets from all unadmitted flows are directed to a
• Aggregate action—Aggregate action could either be a regular QoS action such as mark or set, which is
Cisco ASR 9000 Series Aggregation Services Router Modular Quality of Service Configuration Guide, Release
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L4 protocol, sport, dport)
bandwidth to decide how many video calls/flows to allow pass through a system without causing
congestion.
flows that exceed a predetermined admissible bandwidth to a default queue thereby providing guaranteed
service on a per-flow basis.
flow age timeouts based on the traffic profile. You can set a timeout and ensure service fairness.
IP address (dst-ip) or 5-tuple parameters.
The flow tuples that define a flow can be configured at a per-class level.
referred to the flow table cache.
are learnt into the cache before the maximum limit is hit is called the flow age. Flow Age is also called
as Idle Timeout.
capabilities to admit or reject individual traffic flows at a per-user or per-application level is known as
Video CAC. Video CAC is also known as Video Q or flow aware CAC.
different child class. The QoS action for the redirected packets depends on the configuration of the
"redirect" class.
enforced on each flow, but is common to all flows or an aggregate parent policer / queuing action enforced
on all flows.
Configuring Flow Aware QoS