VPP: Add comprehensive VPP documentation

This commit introduces extensive documentation for VyOS VPP (Vector Packet Processing)
Dataplane interfaces and features, including examples.

Features documented:
* VPP integration description, base requirements and limitations
* VPP dataplane core settings
* Features enabled in the dataplane: ACL, IPsec, NAT, sFlow
* VPP interface types: bonding, bridge, GRE, IPIP, kernel, loopback, VXLAN, XConnect

Note: This is an initial documentation version that will require ongoing improvements
based on user feedback and questions, real-world deployment testing and validation, additional
use cases and configuration scenarios discovered in production. Therefore, all pages are
marked as "need improvement".

1 files changed, 135 insertions, 0 deletions

diff --git a/docs/vpp/configuration/interfaces/vxlan.rst b/docs/vpp/configuration/interfaces/vxlan.rst
new file mode 100644
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+:lastproofread: 2025-09-04
+
+.. _vpp_config_interfaces_vxlan:
+
+.. include:: /_include/need_improvement.txt
+
+#######################
+VPP VXLAN Configuration
+#######################
+
+VPP VXLAN interfaces provide Virtual eXtensible Local Area Network tunneling with high-performance packet processing. VXLAN extends Layer 2 domains across Layer 3 networks using UDP encapsulation, enabling scalable multi-tenant networking while leveraging VPP's optimized data plane.
+
+Basic Configuration
+-------------------
+
+Creating a VXLAN Interface
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN>
+
+   Create a VXLAN interface where ``<vxlanN>`` follows the naming convention vxlan1, vxlan2, etc.
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> vni <vni>
+
+   Set the Virtual Network Identifier (VNI) for the VXLAN tunnel. Valid range is 0-16777214.
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> remote <address>
+
+   Set the tunnel remote endpoint address. Supports both IPv4 and IPv6 addresses.
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> source-address <address>
+
+   Set the tunnel source address. Must match an address configured on the local system.
+
+**Basic Example:**
+
+.. code-block:: none
+
+   set vpp interfaces vxlan vxlan1
+   set vpp interfaces vxlan vxlan1 vni 100
+   set vpp interfaces vxlan vxlan1 remote 203.0.113.2
+   set vpp interfaces vxlan vxlan1 source-address 192.168.1.1
+
+Interface Configuration
+-----------------------
+
+Description and Administrative Control
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> description <description>
+
+   Set a descriptive name for the VXLAN interface.
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> disable
+
+   Administratively disable the VXLAN interface.
+
+Kernel Interface Integration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. cfgcmd:: set vpp interfaces vxlan <vxlanN> kernel-interface <interface-name>
+
+   Bind a kernel interface to the VXLAN tunnel for management and application compatibility.
+
+For detailed information about kernel interface integration, see :doc:`kernel`.
+
+Configuration Examples
+----------------------
+
+Basic VXLAN Tunnel
+^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: none
+
+   # IPv4 VXLAN tunnel
+   set vpp interfaces vxlan vxlan1
+   set vpp interfaces vxlan vxlan1 description "Tenant A network extension"
+   set vpp interfaces vxlan vxlan1 vni 1000
+   set vpp interfaces vxlan vxlan1 remote 203.0.113.10
+   set vpp interfaces vxlan vxlan1 source-address 192.168.1.1
+
+IPv6 VXLAN Tunnel
+^^^^^^^^^^^^^^^^^
+
+.. code-block:: none
+
+   # IPv6 endpoints
+   set vpp interfaces vxlan vxlan2
+   set vpp interfaces vxlan vxlan2 vni 2000
+   set vpp interfaces vxlan vxlan2 remote 2001:db8::2
+   set vpp interfaces vxlan vxlan2 source-address 2001:db8::1
+
+VXLAN with Kernel Interface
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: none
+
+   # VXLAN tunnel with management interface
+   set vpp interfaces vxlan vxlan3
+   set vpp interfaces vxlan vxlan3 vni 3000
+   set vpp interfaces vxlan vxlan3 remote 203.0.113.30
+   set vpp interfaces vxlan vxlan3 source-address 192.168.1.1
+   set vpp interfaces vxlan vxlan3 kernel-interface vpptun3
+   set vpp kernel-interfaces vpptun3 address 10.0.3.1/24
+
+Bridge Integration
+------------------
+
+VXLAN interfaces are commonly used as members in VPP bridges for Layer 2 extension. See :doc:`bridge` for detailed bridge configuration.
+
+.. code-block:: none
+
+   # Add VXLAN tunnel to bridge
+   set vpp interfaces bridge br1
+   set vpp interfaces bridge br1 member interface vxlan1
+   set vpp interfaces bridge br1 member interface eth1
+   set vpp interfaces bridge br1 member interface lo1 bvi
+
+Multi-Tenant Configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: none
+
+   # Multiple VNIs for tenant separation
+   set vpp interfaces vxlan vxlan10
+   set vpp interfaces vxlan vxlan10 description "Tenant A - Production"
+   set vpp interfaces vxlan vxlan10 vni 1001
+   set vpp interfaces vxlan vxlan10 remote 203.0.113.20
+   set vpp interfaces vxlan vxlan10 source-address 192.168.1.1
+   
+   set vpp interfaces vxlan vxlan11
+   set vpp interfaces vxlan vxlan11 description "Tenant A - Development"
+   set vpp interfaces vxlan vxlan11 vni 1002
+   set vpp interfaces vxlan vxlan11 remote 203.0.113.21
+   set vpp interfaces vxlan vxlan11 source-address 192.168.1.1