configured PFC buffer size, the system determines whether this reduction in size is
valid without disrupting the existing configuration. In such a scenario, you must
disable and re-enable DCB. For example, if you modify the total buffer size to be
4000 KB from the previous size of 5000 KB, an error message is displayed that this
reduction cannot be performed owing to existing system configuration because of
queues that are being currently processed.
The lossless queue limit per port is validated based on the dcb pfc-queues
command. PFC queue configuration identifies the maximum number of queues a
port can support. Although the queue limit per port is a baseline when dynamic
buffering is enabled, the limit per port for queues depends on the availability of the
buffer.
Example Dell(conf)#dcb pfc-total-buffer-size 5000
Dell(conf)#dcb pfc-total-buffer-size 4000 %ERROR: Total pfc
buffer size configured cannot accommodate existing buffer
requirement in the system.
dcb pfc-queues
Configure the number of PFC queues.
Syntax dcb pfc-queues value
Parameters value Enter the number of PFC queues in the range of 0 through 4.
The number of ports supported based on lossless queues
configured will depend on the buffer.
Default The default number of PFC queues in the system is 2 for S4810 and 1 for S6000
platforms.
Command
Modes
CONFIGURATION mode
Command
History Version Description
9.7(0.0) Introduced on the Z9500.
Usage
Information
You can configure up to a maximum of four lossless (PFC) queues. By configuring
four lossless queues, you can configure four different priorities and assign a
particular priority to each application that your network is used to process. For
example, you can assign a higher priority for time-sensitive applications and a
lower priority for other services, such as file transfers. You can configure the
amount of buffer space to be allocated for each priority and the pause or resume
thresholds for the buffer. This method of configuration enables you to effectively
manage and administer the behavior of lossless queues.
644 Data Center Bridging (DCB)