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Scheduler Settings

Each forwarding class has an associated scheduler priority. Only two forwarding classes, best-effort and network-control (queue 0 and queue 3), are used in the JUNOS default scheduler configuration.

By default, the best-effort forwarding class (queue 0) receives 95 percent, and the network-control (queue 3) receives 5 percent of the bandwidth and buffer space for the output link. The default drop profile causes the buffer to fill and then discard all packets until it again has space.

The expedited-forwarding and assured-forwarding classes have no schedulers, because by default no resources are assigned to queue 1 and queue 2. However, you can manually configure resources for expedited-forwarding and assured-forwarding.

By default, each queue can exceed the assigned bandwidth if additional bandwidth is available from other queues. When a forwarding class does not fully use the allocated transmission bandwidth, the remaining bandwidth can be used by other forwarding classes if they receive a larger amount of offered load than the bandwidth allocated. If you do not want a queue to use any leftover bandwidth, you must configure it for strict allocation. For more information, see Configuring Strict High Priority for Queuing with a Configuration Editor.

The device uses the following default scheduler settings. You can modify these settings through configuration. For instructions, see Configuring Class of Service.



[edit class-of-service]
schedulers {


network-control {
transmit-rate percent 5;
buffer-size percent 5;
priority low;
drop-profile-map loss-priority any protocol any drop-profile
terminal;
}




best-effort {
transmit-rate percent 95;
buffer-size percent 95;
priority low;
drop-profile-map loss-priority any protocol any drop-profile
terminal;
}


}
drop-profiles {


terminal {






fill-level 100 drop-probability 100;


}


}

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