Configuring The Dynamic Buffer Method - Dell C9000 Series Networking Configuration Manual

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The default behavior causes up to a maximum of 6.6 MB to be used for PFC-related traffic. The remaining

approximate space of 1 MB can be used by lossy traffic. You can allocate all the remaining 1 MB to lossless

PFC queues. If you allocate in such a way, the performance of lossy traffic is reduced and degraded. Although

you can allocate a maximum buffer size, it is used only if a PFC priority is configured and applied on the

The number of lossless queues supported on the system is dependent on the availability of total buffers for

PFC. The default configuration in the system guarantees a minimum of 52 KB per queue if all the 128 queues

are congested. However, modifying the buffer allocation per queue impacts this default behavior.

By default the total available buffer for PFC is 6.6 MB and when you configure dynamic ingress buffering, a

minimum of least 52 KB per queue is used when all ports are congested. By default, the system enables a

maximum of 1 lossless queue on the switch.

This default behavior is impacted if you modify the total buffer available for PFC or assign static buffer

configurations to the individual PFC queues.

Configuring the Dynamic Buffer

Priority-based flow control using dynamic buffer spaces is supported on the switch.

To configure the dynamic buffer capability, perform the following steps:

Enable the DCB application. By default, DCB is enabled and link-level flow control is disabled on all

CONFIGURATION mode

Configure the shared PFC buffer size and the total buffer size. A maximum of 4 lossless queues are

CONFIGURATION mode

dcb pfc-shared-buffer-size 2000

dcb pfc-total-buffer-size 5000

Configure the number of PFC queues.

CONFIGURATION mode

dcb enable pfc-queues pfc-queues

The number of ports supported based on lossless queues configured will depend on the buffer. The

default number of PFC queues in the system is two.

For each priority, you can specify the shared buffer threshold limit, the ingress buffer size, buffer limit for

pausing the acceptance of packets, and the buffer offset limit for resuming the acceptance of received

Configure the profile name for the DCB buffer threshold

Data Center Bridging (DCB)

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