
Specifying actions
25
As classifier blocks are planned, keep in mind that only a single IP classifier
element, a single L2 classifier element, and a single system classifier
element can appear in each classifier. For example, to group five IP classifier
elements create five separate classifiers, each with a unique IP classifier
element, and then create a classifier block referencing those five classifiers.
All classifiers that are part of a single classifier block (that is, with the same
block number) must each filter on identically the same parameters at the
packet level. This includes the same mask, range, and VLAN tag type. If
this criterion is not met, an error message is generated when an attempt
to create the classifier block, or to add a new member to an existing block,
is made. Also, if one of the classifier elements in a classifier block has
associated actions or meters, then all classifier elements of that classifier
block must also have associated actions or meters (not identical actions or
meters, but also associated actions or meters).
A classifier or classifier block is associated through a policy with interface
groups. Packets received from any port that is in an interface group are
classified with the same filter criteria.
Each classifier or classifier block is associated with actions that are
executed when the packet matches the filter criteria in the group. The filter
criteria and the associated actions, metering criteria, and interface groups
are referenced by a policy, which dictates the overall traffic treatment (refer
to
"Flowchart of QoS Actions" (page 26)
for an illustration of the traffic
treatment).
Classifier elements, through individual classifiers or a classifier block, are
associated with an interface group, action, and metering through a policy.
Multiple policies can be applied to a given flow. The policy evaluation order
is determined by the policy precedence. The order of precedence is from
the highest precedence value to the lowest precedence (that is, a value of
7 is evaluated before a value of 6).
ATTENTION
Classifier blocks, not individual classifiers that comprise a block, can be
associated with a meter or action.
In summary, classifiers combine different classifier elements. Classifier
blocks combine classifiers to form an unordered set of classification data.
Unordered data means that all classifiers associated with a policy are
applied as if simultaneously, with no precedence.
Specifying actions
"Flowchart of QoS Actions" (page 26)
summarizes how QoS matches
packets with actions.
Nortel Ethernet Routing Switch 4500 Series
Configuration — Quality of Service
NN47205-504 (322816-
B
)
03.01
Standard
5.1
23 November 2007
Copyright © 2007, Nortel Networks
.
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