Connectivity Guide

Buffer management
OS10 devices distribute the total available buffer resources into two buffer pools at ingress direction and three buffer pools at
egress direction of all physical ports.
All ports in a system are allocated a certain amount of buffers from corresponding pools based on the configuration state of
each priority-group or queue. The remaining buffers in the pool are shared across all similarly configured ports.
The following buffer pools are available:
● Ingress buffer pools:
○ Lossy pool (default)
○ Lossless pool (PFC)
● Egress buffer pools:
○ Lossy pool (default)
○ Lossless pool (PFC)
○ CPU pool (CPU control traffic)
For example, when all ports are allocated as reserved buffers from the lossy (default) pool, the remaining buffers in the lossy
pool are shared across all ports, except the CPU port.
When you enable priority flow control (PFC) on the ports, all the PFC-enabled queues and priority-groups use the buffers from
the lossless pool.
OS10 dedicates a separate buffer pool for CPU traffic. All default reserved buffers for the CPU port queues are from the CPU
pool. The remaining buffers are shared across all CPU queues. You can modify the buffer settings of CPU queues.
You can configure the size of the CPU pool using the control-plane-buffer-size command.
OS10 allows configuration of buffers per priority-group and queue for each port.
Buffer-usage accounting happens for ingress packets on ingress pools and egress packets on egress pool. You can configure
ingress-packet buffer accounting per priority-group and egress-packet buffer accounting per queue level.
Configure ingress buffer
In default ingress buffers, all traffic classes map to the default priority group. The buffers are reserved per default priority group
ID 7. All buffers are part of the default pool and all ports share buffers from the default pool.
The reserved buffer size is 9360 bytes for the speed of 10G, 25G, 40G, 50G, and 100G. The supported speed varies for
different platforms.
Table 64. Maximum buffer size
Platforms Max buffer size
S4000 12 MB
S6010–ON, S4048–ON 16 MB
S4100-ON Series 12 MB
S4200-ON Series 3 GB
S5148F-ON 16 MB
S5200-ON Series 32 MB
Z9100–ON 16 MB
Z9264F-ON 42 MB
The following lists the link-level flow control (LLFC) buffer settings for default priority group 7:
Table 65. Default setting for LLFC
Speed 10G 25G 40G 50G 100G
Default reserved buffer 9KB 9KB 18KB 18KB 36KB
932 Quality of service