Juniper JUNOS OS 10.3 - SOFTWARE, Руководство пользователя

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Priority scheduling is accomplished through a procedure in which the scheduler examines
the priority of the queue. Juniper Networks Junos operating system (Junos OS) supports
two levels of transmission priority:
• Low—The scheduler determines if the individual queue is within its defined bandwidth
profile. This binary decision, which is reevaluated on a regular time cycle, compares
the amount of data transmitted by the queue against the amount of bandwidth
allocated to it by the scheduler. When the transmitted amount is less than the allocated
amount, the queue is considered to be in profile. A queue is out of profile when its
transmitted amount is larger than its allocated amount. Out of profile queue will be
transmitted only if bandwidth is available. Otherwise, it will be buffered.
A queue from the set is selected based on the shaped deficit weighted round robin
(SDWRR) algorithm, which operates within the set.
• Strict-high—Strict-high priority queue receives preferential treatment over low priority
queue. Unlimited bandwidth is assigned to strict-high priority queue. Queues are
scheduled according to the queue number, starting with the highest queue 7, with
decreasing priority down through queue 0. Traffic in higher queue numbers is always
scheduled prior to traffic in lower queue numbers. In other words, in case of two high
priority queues, the queue with higher queue number is processed first.
Packets in low priority queues are transmitted only when strict-high priority queues are
empty.
Scheduler Drop-Profile Maps
Drop-profile maps associate drop profiles with a scheduler. Drop-profile map sets the
drop profile for a specific packet loss priority (PLP) and protocol type. The inputs for the
drop-profile map are the PLP and the protocol type. The output is the drop profile.
Scheduler Maps
A scheduler map associates a specified forwarding class with a scheduler configuration.
After configuring a scheduler, you must include it in a scheduler map and then associate
the scheduler map with an output interface.
Juniper Networks EX Series Ethernet Switches allow you to associate up to four
user-defined scheduler maps with interfaces.
Related
Documentation
Understanding Junos OS CoS Components for EX Series Switches on page 3148
•
•
Example: Configuring CoS on EX Series Switches on page 3173
•
Defining CoS Schedulers (CLI Procedure) on page 3209
•
Defining CoS Schedulers (J-Web Procedure) on page 3211
Copyright © 2010, Juniper Networks, Inc. 3162
Complete Software Guide for Junos
®
OS for EX Series Ethernet Switches, Release 10.3