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Question How do schedulers provide different treatment to the different forwarding classes? Answer You use schedulers to define the class-of-service (CoS) properties of forwarding classes and output queues. You configure CoS properties in a scheduler, then map the scheduler to a forwarding class. Forwarding classes are in turn mapped to output queues. Schedulers determine the amount of interface bandwidth assigned to each queue on an interface, the size of the memory buffer allocated for storing packets in each queue, the scheduling priority of each queue, and the random early detection (RED) drop profiles associated with each queue to control packet drop during periods of congestion. See https://www.juniper.net/techpubs/en US/junos15.1/topics/concept/schedulers-overview-cos-config-guide.html #ClassofService #QOS #qualityofservice #COS #FAQ
Question What is the default scheduler policy for Junos CoS on routing devices?
Answer Hierarchical class of service (HCoS) is the ability to provide CoS functionality as a more granular level (for example, per subscriber rather than per port) by applying traffic schedulers and shapers to a hierarchy of scheduler nodes . Each level of the scheduler hierarchy can be used to treat traffic based on different criteria such as per application, user, VLAN, and physical port
Answer Use traffic-manager mode with the following options to configure CoS traffic manager mode of operation: egress-only—Enables CoS queuing and scheduling on the egress side for the PIC that houses the interface
Answer Support for PIR and CIR on MPCs On MX Series devices using MPCs, CIR and PIR are supported at the queue level with class-of-service (CoS) schedulers. Use three rates, transmit-rate, shaping-rate, and excess-rate, which can be configured simultaneously, and use the excess-priority statement with excess-rate to manage the bandwidth in the excess region between CIR and PIR, as follows: excess-rate—Use to configure the percentage of excess bandwidth traffic that should go into the queue in the excess region
How many forwarding classes does Junos CoS support? How do schedulers provide different treatment to the different forwarding classes?...What is the default scheduler policy for Junos CoS on routing devices?
You map incoming traffic to a forwarding class, define the class-of-service (CoS) properties for the forwarding class through a scheduler, and assign the forwarding class to an output queue
You can configure drop profiles that determine the probability of dropping a queued packet based on the fullness of the queue and then map those drop profiles to PLPs for a particular scheduler. For example, you would create a drop profile that drops packets aggressively and map it to the high PLP and map a conservative drop profile to the low PLP
Is it possible to use a common QoS scheduler on a traffic-class group comprised of an aggregate of multiple GRE tunnels?