Reference Guide

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 Z9500
platform.
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 Method
Priority-based flow control using dynamic buffer spaces is supported on the platform.
To configure the dynamic buffer capability, perform the following steps:
1. Enable the DCB application. By default, DCB is enabled and link-level flow control is disabled on all interfaces.
CONFIGURATION mode
dcb enable
2. Configure the shared PFC buffer size and the total buffer size. A maximum of 4 lossless queues are supported.
CONFIGURATION mode
dcb pfc-shared-buffer-size 2000
dcb pfc-total-buffer-size 5000
3. 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 S4810 and Z9500, and one for S6000 platforms.
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 packets.
4. Configure the profile name for the DCB buffer threshold
CONFIGURATION mode
dcb-buffer-threshold dcb-buffer-threshold
5.
DCB-BUFFER-THRESHOLD mode
priority 0 buffer-size 52 pause-threshold 16 resume-offset 10 shared-threshold-weight 7
6. Assign the DCB policy to the DCB buffer threshold profileon backplane.
CONFIGURATION mode
dcb-policy buffer-threshold linecard {linecard-number | all} port-set {port-pipe | all}
backplane all dcb-policy-name
7. Assign the DCB policy to the DCB buffer threshold profile on interfaces. This setting takes precedence over the default
buffer-threshold setting.
INTERFACE mode (conf-if-te)
dcb-policy buffer-threshold buffer-threshold
8. Configuring DCB buffer on SFM ports.
CONFIGURATION mode
dcb-policy buffer-threshold sfm all [port-set all] dcb-policy-name
9. Configuring Global total buffer size on linecards.
CONFIGURATION mode
dcb pfc-total-buffer-size buffer-size linecard {linecard-number | all}
Line card number range is from 0 to 2.
10. Configuring DCB global total buffer on SFM ports.
CONFIGURATION mode
dcb pfc-total-buffer-size buffer-size sfm all
11. Configuring DCB global shared buffer on SFM ports.
Data Center Bridging (DCB)
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