3Com CoreBuilder 3500, Implementation Manual, Page: 492 / 592

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Specifying Rate Limits A rate limit restricts the amount of input bandwidth used by incoming
classified traffic (optionally, on a per-port basis). When you define a
control, you can specify one of three rate limits:
■
None — No rate limit
■
ReceivePort — Imposes a separate limit on each receive port
■
Aggregate
— Imposes limits on groups of receive ports. This rate
limit type can only be applied to flow classifiers.
Your choice of rate limit determines how much additional information
you need to supply. The default rate limit is
none . If you specify a rate
limit of none, there is no rate limit applied to the classifier. With this rate
limit type, you then have a small subset of options to specify. You select a
service level and loss-eligibility status for conforming packets (packets
that are below the rate limit), decide if you want to apply an IEEE 802.1p
priority tag value to forwarded frames (for service levels other than drop),
and specify the classifiers you want to associate with the control.
If you specify a rate limit of receivePort or aggregate , you have many
additional options. After you specify a service level and loss-eligibility
status for conforming packets, you can also specify a service level for
nonconforming excess packets (packets that exceed the specified rate
limit), whether the nonconforming excess are loss eligible, how the rate
limit for receive ports should be expressed, the rate-limit value, a burst
size, and the receive ports for which you want to enable the rate limit.
(The rate limit sets a bandwidth limit for a specific set of ports. You can
specify multiple rate-limit values for different subsets of ports. As with
any rate limit type, you can additionally specify an IEEE 802.1p priority tag
value on forwarded frames.)
When you specify how a receivePort or aggregate rate limit is expressed,
you can select a percentage of port bandwidth or KBytes/sec:
■
For KBytes/sec as a rate limit (the default), specify the value for the
rate limit in KBytes/sec (
0 through 65434 ).
■
For a percentage for the rate limit, specify the percentage in the range
of from
0 to 100 percent. These numbers are rounded to the nearest
16 KBytes. A value of 0 makes all packets nonconforming excess
packets. The system drops these packets only if the service level for
excess packets is set to
drop .