Nortel business policy switch 2000, Руководство пользователя

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Chapter 4 Policy-enabled networks 305
Using the Business Policy Switch 2000 Version 2.0
The policies, by connecting these user-defined configurations, control the traffic
on the switch.
Ports are assigned to interface groups that are linked to policies. Although a single
policy can reference only one interface group, you can configure several policies
that reference the same interface group.
The policies determine the traffic
treatment of the flows.
Beginning with software version 2.0, you can enable or disable policies; you do
not have to delete a policy to disable it. However, you still have to delete a policy
to modify it.
Packet flow using QoS
Using DiffServ and QoS, you can designate a specific performance level for
packets. This system allows you to prioritize network traffic. However, it requires
some thought to configure the prioritizations.You can specify a number of
policies, and each policy can match one or many flows—supporting complex
classification scenarios.
This section contains a very simplified introduction to the many ways to prioritize
packets using QoS. In simple terms, the methods of prioritizing packets depend on
the DSCP and the 802.1 priority level and drop precedence.
The QoS class basically directs which group of packets receives the best network
throughput, which group of packets receives the next best throughput, and so on.
The level of service for each packet is determined by the configurable DSCP.
The available levels of QoS classes are currently named Premium, Platinum,
Gold, Silver, Bronze, and Standard. The level of service for each packet is
determined by the configurable DSCP.
Filters and filter groups basically sort the packets by various configurable
parameters. These parameters include VLAN IDs, IP source and subnet address,
IP protocol, and many others.