Nortel BCM 3.7, Manual

Page: 797 / 1004

Policy configuration overview 797
Programming Operations Guide
Figure 219 DiffServ bandwidth brokers and nodes
DiffServ components
The DiffServ architecture is comprised of the following components:
• Traffic conditioners — These components include classifiers, DiffServ-byte markers, shapers,
policiers and profilers. Marking is performed at network boundaries, including the edges of
the network (first hop router or switch or source host) and administrative boundaries between
networks or autonomous systems. Traffic conditions should exist at DiffServ ingress and
egress nodes. Business Communications Manager is an edge switch that supports packet
classification based on header information in layer 3 and layer 4 of the Open System
Interconnection (OSI) layering model. Business Communications Manager can mark and
re-mark IP traffic based on the policies you define.
• Packet schedulers and queue managers — PHBs are expected to be implemented by
employing a range of queue service and/or queue management disciplines on a network node
output interface queue (for example, weighted fair queueing or drop preference queue
management). DiffServ does not require a particular discipline for queue management or
servicing to realize a particular service. All DiffServ nodes should support the packet
scheduling and queue management algorithms that are necessary to implement the required
PHB.
Business Communications Manager supports a queue service discipline that allows packets to
be serviced in an absolute priority fashion or using a weighted fair queueing scheduler. This
service discipline ensures that packets in the highest-priority queue are serviced quickly
without starving lower-priority queues.
• Bandwidth brokers (not supported in Business Communications Manager) — Bandwidth
brokering is responsible for bandwidth allocation, QoS policy management, and flow
admission control in a given DiffServ domain. Business Communications Manager does not
support bandwidth brokering or traffic admission control.
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