Header Fields - Juniper ACX1000 Configuration Manual

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Overview of Assigning Service Levels to Packets Based on Multiple Packet Header
Fields
Copyright © 2017, Juniper Networks, Inc.
}
host-outbound-traffic {
ieee-802.1 {
rewrite-rules;
}
}
Configuring the IEEE 802.1p Field for CoS Host Outbound Traffic in ACX Series on
page 889
Configuring a Global Default IEEE 802.1p Value for All Host Outbound Traffic in ACX
Series on page 889
Behavior aggregate (BA) classification (see
Classifiers Prioritize Trusted Traffic" on page
their QoS markings, is the most common way to assign service levels because it is
straightforward and based on a well-established, fixed-length header fields, which makes
them computationally more efficient. However, sometimes BA classification does not
provide sufficient granularity, or the QoS markings in the packet headers cannot be
trusted. In such situations, multifield classifiers can be used. A multifield classifier is a
method of classifying traffic flows based on multiple packet header fields. Devices that
sit at the edge of a network usually classify packets based on multiple packet header
fields. Multifield classification is normally performed at the network edge because of the
general lack of DiffServ code point (DSCP) or IP precedence support in end-user
applications.
In an edge router, a multifield classifier provides the filtering functionality that scans
through a variety of packet header fields to determine the forwarding class for a packet.
Typically, a classifier performs matching operations on the selected fields against a
configured value. A multifield classifier can examine multiple fields in the packet header:
destination address, source address, IP protocol, source port, destination port, and DSCP
value. Multifield classifiers are used when a simple BA classifier is insufficient to classify
a packet.
Figure 56 on page 892 provides a high-level illustration of how a classifier works.
Chapter 27: Configuring Class of Service
"Understanding How Behavior Aggregate
950), where packets are classified based on
891