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authorYuriy Andamasov <yuriy@vyos.io>2026-05-02 17:25:47 +0300
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+---
+lastproofread: '2026-02-23'
+---
+
+(vpp-config-dataplane-buffers)=
+
+```{include} /_include/need_improvement.txt
+```
+
+
+# VPP Dataplane Buffers Configuration
+
+Buffers are essential for handling network packets efficiently. Proper
+configuration enhances performance and reliability, and is mandatory for
+VPP to work. Buffers temporarily store packets during processing. Therefore,
+their configuration must be in sync with NIC configuration, CPU threads, and
+overall system resources.
+
+:::{important}
+VPP buffers are allocated from the physical memory pool (`physmem`). The
+total amount of memory available for buffer allocation is controlled by the
+`physmem-max-size` setting, while the buffer configuration parameters
+below control how that memory is used for buffer allocation.
+
+See {ref}`VPP Physical Memory Configuration <vpp-config-dataplane-physmem>`
+for details on configuring `physmem`.
+:::
+
+## Buffer Configuration Parameters
+
+The following parameters can be configured for VPP buffers:
+
+### buffers-per-numa
+
+Number of buffers allocated per NUMA node. This setting optimizes
+memory access patterns for multi-CPU systems.
+
+Typically, you need to tune this value if:
+- The system has many interfaces
+- NICs have many queues
+- NICs have large descriptor sizes
+
+Set this value carefully to balance memory usage and performance.
+
+```{cfgcmd} set vpp settings resource-allocation buffers buffers-per-numa \<value\>
+```
+
+The common approach for the calculation is to use the formula:
+
+```none
+buffers-per-numa = (num-rx-queues * num-rx-desc) + (num-tx-queues * num-tx-desc)
+```
+
+Calculate this formula for each NIC and sum the results. Multiply the
+total by 2.5 to get the minimum recommended value for
+`buffers-per-numa`.
+
+Avoid setting this value too low to prevent packet drops.
+
+### data-size
+
+This value sets how much payload data can be stored in a single buffer
+allocated by VPP. Larger values reduce buffer chains for large packets,
+while smaller values conserve memory for environments handling mostly
+small packets.
+
+```{cfgcmd} set vpp settings resource-allocation buffers data-size \<value\>
+```
+
+Optimal size depends on the typical packet size in your network. If
+unsure, use the largest MTU in your network plus overhead (for example,
+128 bytes).
+
+### page-size
+
+A memory pages type used for buffer allocation. Common values are 4K, 2M, or 1G.
+
+Use page sizes configured in your system settings.
+
+```{cfgcmd} set vpp settings resource-allocation buffers page-size \<value\>
+```
+
+
+## Potential Issues and Troubleshooting
+
+Improper buffer configuration can lead to issues such as:
+
+- Increased latency and packet loss
+- Inefficient CPU utilization
+- Interface initialization failures
+
+Indicators of such issues are:
+
+- Errors during interfaces initialization in VPP logs
+- Packet drops observed in VPP statistics
+
+To troubleshoot buffer-related issues, consider the following steps:
+
+- Review VPP logs for errors related to buffer allocation. Look for
+ error `-5` messages.
+- Tune available buffers by adjusting the `buffers-per-numa` and
+ `data-size` parameters.