Alcatel-Lucent 7450 Quality Of Service Manual page 38

QoS Policies
Service ingress QoS policies are applied to the customer-facing Service Access Points (SAPs)
and map traffic to forwarding class queues on ingress. The mapping of traffic to queues can
be based on combinations of customer QoS marking (IEEE 802.1p bits, DSCP, and TOS
precedence), IP and MAC criteria. The characteristics of the forwarding class queues are
defined within the policy as to the number of forwarding class queues for unicast traffic and
the queue characteristics. There can be up to eight (8) unicast forwarding class queues in the
policy; one for each forwarding class. A service ingress QoS policy also defines up to three
(3) queues per forwarding class to be used for multipoint traffic for multipoint services. In the
case of the VPLS, four types of forwarding are supported (which is not to be confused with
forwarding classes); unicast, multicast, broadcast, and unknown. Multicast, broadcast, and
unknown types are flooded to all destinations within the service while the unicast forwarding
type is handled in a point-to-point fashion within the service.
Service egress QoS policies are applied to SAPs and map forwarding classes to service egress
queues for a service. Up to 8 queues per service can be defined for the 8 forwarding classes.
A service egress QoS policy also defines how to remark the forwarding class to IEEE 802.1p
bits in the customer traffic.
Network QoS policies are applied to IP interfaces. On ingress, the policy applied to an IP
interface maps incoming DSCP and EXP values to forwarding class and profile state for the
traffic received from the core network. On egress, the policy maps forwarding class and
profile state to DSCP and EXP values for traffic to be transmitted into the core network.
Network queue policies are applied on egress to network ports and channels and on ingress
to XMAs or MDAs. The policies define the forwarding class queue characteristics for these
entities.
Service ingress, service egress, and network QoS policies are defined with a scope of either
template or exclusive. Template policies can be applied to multiple SAPs or IP interfaces
whereas exclusive policies can only be applied to a single entity.
One service ingress QoS policy and one service egress QoS policy can be applied to a specific
SAP. One network QoS policy can be applied to a specific IP interface. A network QoS policy
defines both ingress and egress behavior.
If no QoS policy is explicitly applied to a SAP or IP interface, a default QoS policy is applied.
A summary of the major functions performed by the QoS policies is listed in
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• Network queue (for ingress and egress)
• ATM traffic descriptor profile
• Scheduler
• Shared queue
• Slope
Table 4.
Quality of Service Guide