QoS Policies
Quality of Service Guide 75
However, as a tradeoff, the total amount of traffic throughput at ingress of the node is reduced
because any ingress packet serviced by a shared-queuing SAP is recirculated for further
processing. When the node is only used for access SAPs, 5 Gbps ingress traffic is the
maximum that can be processed without seeing packet drops at the MDA ingress. The reason
for this is that any ingress packet serviced by a shared-queuing SAP is processed twice in the
forwarding plane which greatly reduces bandwidth.
Shared-queuing can add latency. Network planners should consider these restrictions while
trying to scale services on one MDA.
ATM Traffic Descriptor Profiles
Traffic descriptors profiles capture the cell arrival pattern for resource allocation. Source
traffic descriptors for an ATM connection include at least one of the following:
• Sustained Information Rate (SIR)
• Peak Information Rate (PIR)
• Minimum Information Rate (MIR)
• Maximum Burst Size (MBS)
QoS Traffic descriptor profiles are applied on IES, VPRN, VPLS, and VLL SAPs.
ATM traffic descriptors are not supported on the 7950 XRS.
Configuration Notes
The following information describes QoS implementation caveats:
• Creating additional QoS policies is optional.
• Default policies are created for service ingress, service egress, network, network-
queue, slope policies. Scheduler policies must be explicitly created and applied to a
port.
• Associating a service or access ports with a QoS policy other than the default policy
is optional.
• A network queue, service egress, and service ingress QoS policy must consist of at
least one queue. Queues define the forwarding class, CIR, and PIR associated with
the queue.
To Next Page
Loading...
