Overview
The buffer is configured to implement traffic control and PFC watchdog, which is based on interface and priority queue. The storage space of each interface is divided into different buffers independently and a certain action will be executed after the number of accumulated packets reaches the buffer threshold (the unit is cell).
Guaranteed: the dedicated buffer available for a specified queue. This buffer space cannot be used by other queues.
Shared: the public buffer available for all queues. The shared buffer will be occupied when the guaranteed buffer reaches the threshold.
Headroom: the maximum number of cell resources available for packets with a specific 802.1p priority. When the occupied shared buffer reaches the threshold, the packets will be saved in the headroom buffer.
Threshold and Execution
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Action
After the PFC function is enabled, the default storage space is available for a specified queue of an interface. To flexibly control the PFC function and make good use of the storage space, you can configure the thresholds for different buffer types and the correspongding action will be executed. The detailed information is shown as below.
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When the occupied space is higher than the headroom buffer threshold, the packets will be dropped.
Restrictions and Guidelines
When you configure PFC buffer, follow these restrictions and guidelines:
PFC should be enabledon the interface before configuring PFC buffer.
Currently, the PFC buffer is only supported on Trident3-X5, Trident3-X7 and Tomahawk3 platforms.
The values of cell are different on different platforms. The value is 256 bytes on Trident3-X5 and Trident3-X7 platforms, and is 254 bytes on the Tomahawk3 platform.
Procedure
Step 1 Enable PFC on the interface before configuring PFC buffer.
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Step 8 Commit the configuration.
commit