fix: re-add 4 canary md-*.md files deleted by 242b334a

Commit 242b334a accidentally staged deletions instead of modifications
because the working tree had unprefixed *.md files left over from an
incomplete swap-restore cycle. Re-imports the same 4 files from
origin/myst/current with the xref label fixes applied:

- contributing/md-development.md       — (coding-guidelines)= anchor
- operation/md-upgrade-recovery.md     — how_it_works → how-it-works,
                                         cancelling_recovery → cancelling-recovery
- vpp/configuration/dataplane/md-buffers.md — vpp_config_dataplane_physmem
                                              → vpp-config-dataplane-physmem
- vpp/configuration/dataplane/md-unix.md   — vpp_config_dataplane_interface_rx_mode
                                              → vpp-config-dataplane-interface-rx-mode

Source: origin/myst/current commit 59fbe3ea.

🤖 Generated by [robots](https://vyos.io)

1 files changed, 90 insertions, 0 deletions

diff --git a/docs/vpp/configuration/dataplane/md-buffers.md b/docs/vpp/configuration/dataplane/md-buffers.md
new file mode 100644
index 00000000..e9bddec9
--- /dev/null
+++ b/docs/vpp/configuration/dataplane/md-buffers.md
@@ -0,0 +1,90 @@
+---
+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.