You configure class of service
(CoS) when you need to override the default packet forwarding behavior
of a J Series or SRX Series device—especially in the three areas
identified in Table 236.
Table 236: Reasons
to Configure Class of Service (Cos)
Default Behavior to Override with
CoS
CoS Configuration Area
Packet classification—By
default, the J Series or SRX Series device does not use behavior aggregate
(BA) classifiers to classify packets. Packet classification applies
to incoming traffic.
Classifiers
Scheduling queues—By default,
the J Series or SRX Series device has only two queues enabled. Scheduling
queues apply to outgoing traffic.
Schedulers
Packet headers—By default, the J Series
or SRX Series device does not rewrite CoS bits in packet headers.
Rewriting packet headers applies to outgoing traffic.
Rewrite rules
You can use either J-Web Quick Configuration or
a configuration editor to configure CoS. This chapter contains the
following topics. For more information about CoS, see the JUNOS Class of Service Configuration Guide.
For information about which devices support the features documented
in this chapter, see the JUNOS Software Feature Support Reference for SRX Series and J Series Devices.
