Merge pull request #1899 from vyos/feat/myst-as-primary-current

feat: MD as primary, RST as override — Phase 1 (rename + exclude flip on current)

1 files changed, 104 insertions, 0 deletions

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+---
+lastproofread: '2026-02-23'
+---
+
+(vpp-config-dataplane-interface)=
+
+```{include} /_include/need_improvement.txt
+```
+
+
+# VPP Dataplane Interfaces Configuration
+
+Only Ethernet interfaces (physical or virtual) can be connected to the
+VPP dataplane. Interfaces configured here act as a bridge between VPP
+and the outside world, allowing VPP to send and receive network
+packets.
+
+## Interface Configuration Parameters
+
+Interfaces connected to the VPP dataplane use the DPDK driver by default,
+providing high performance and low latency.
+
+```{cfgcmd} set vpp settings interface \<interface-name\>
+```
+
+Some network interface cards (NICs) may not be compatible with the DPDK driver.
+
+### DPDK interface options
+
+This section shows how to configure DPDK-specific settings for an interface.
+
+```{cfgcmd} set vpp settings interface \<interface-name\> num-rx-queues \<value\>
+```
+
+Specifies the number of receive queues for the interface. More queues
+improve performance on multi-core systems by allowing parallel
+processing of incoming packets. Each queue is assigned to a separate
+CPU core.
+
+```{cfgcmd} set vpp settings interface \<interface-name\> num-tx-queues \<value\>
+```
+
+Specifies the number of transmit queues for the interface. Similar to
+receive queues, more transmit queues improve performance by enabling
+parallel processing of outgoing packets. By default, the VPP Dataplane
+has one TX queue per enabled CPU worker, or a single queue if no
+workers are configured.
+
+:::{seealso}
+{doc}`cpu`
+:::
+```{cfgcmd} set vpp settings interface \<interface-name\> num-rx-desc \<value\>
+```
+
+Defines the size of each receive queue. Larger queue sizes accommodate
+bursts of incoming traffic and reduce the likelihood of packet drops
+during high traffic periods.
+
+```{cfgcmd} set vpp settings interface \<interface-name\> num-tx-desc \<value\>
+```
+
+Defines the size of each transmit queue. Larger sizes help manage
+bursts of outgoing traffic more effectively.
+
+## Global Interface Parameters
+
+(vpp-config-dataplane-interface-rx-mode)=
+
+### interface-rx-mode
+
+The `interface-rx-mode` parameter defines how VPP handles incoming
+packets on interfaces. There are several modes available, each with its
+own advantages and use cases:
+- `interrupt`: In this mode, VPP relies on hardware interrupts to
+  notify it of incoming packets. This mode suits low to moderate
+  traffic loads and reduces CPU usage during idle periods. It is not
+  recommended for low-latency processing. Some NICs may not support
+  this mode.
+- `polling`: In polling mode, VPP continuously checks the interface
+  for incoming packets. This mode is ideal for high-throughput
+  scenarios where low latency is critical, as it minimizes packet
+  waiting time. However, it can increase CPU usage, especially during
+  low traffic periods, as the polling process is always active.
+- `adaptive`: Adaptive mode combines the benefits of interrupt and
+  polling modes. VPP starts in interrupt mode and switches to polling
+  mode when traffic load increases.
+
+```{cfgcmd} set vpp settings interface-rx-mode \<mode\>
+```
+
+Choose an rx-mode based on expected traffic patterns and performance
+requirements of your network.
+
+## Potential Issues and Troubleshooting
+
+Improper interface configuration can lead to issues such as:
+
+- Failure to initialize the interface
+- Poor performance due to suboptimal driver selection or settings
+
+Indicators of such issues are:
+
+- Failed commits after adding or modifying an interface settings
+- Low throughput or high latency on the interface