Nortel 2000, Using Manual

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290 Chapter 4 Policy-enabled networks
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Meters, operating at ingress, keep the sorted packets within certain parameters.
You configure a committed rate of traffic, allowing a certain size for a temporary
burst, as In-Profile traffic. All other traffic is configured as Out-of-Profile traffic.
(If you do not wish to configure In-Profile traffic, you must still configure the
Out-of-Profile traffic.)
Actions determine how the traffic is treated.
The overall total of all the interacting QoS factors on a group of packets is a
policy. You configure policies that monitor the characteristics of the traffic and
perform a controlling action on the traffic when certain user-defined
characteristics are matched.
Default QoS settings
The Business Policy Switch is shipped with limited default QoS information.
Defaults include a default interface group, default user priority-to-queue
mappings for each queue set, and default DSCP-to-user priority mappings.
QoS configuration guidelines
You can install filters that will act on traffic destined for the switch itself, such as
ICMP Echo Requests (ping) and SNMP messages. If the associated action is to
drop the traffic, you can lock yourself out of the switch.
However, traffic destined for the switch and received through a port on the base
unit of a stack is not dropped even if filters targeting the traffic are installed and
drop has been specified. This behavior prevents you from completely isolating
yourself from the switch. Consider this behavior when you configure filters and
when you allocate ports for the purposes of configuring and or monitoring the
switch.