feat: flip swap mechanism — MD as primary, RST as override (Phase 1)

This is the first of three phases inverting the per-page swap mechanism
so MD becomes the canonical primary and RST becomes the rare override.

Phase 1 — file renames + conf.py exclude_patterns flip only:
- Rename docs/**/md-<stem>.md to docs/**/<stem>.md (drop md- prefix)
  for all 254 stems previously listed in docs/_swap.txt
- Rename docs/**/<stem>.rst to docs/**/rst-<stem>.rst (add rst- prefix)
  for the same 254 stems
- Repurpose docs/_swap.txt as docs/_rst_overrides.txt; initially empty
  comment-only since no pages need the RST fallback right now
- conf.py exclude_patterns flipped: rst-*.rst is now excluded by default
  instead of md-*.md
- conf.py runtime-artifact references updated to _rst_override_state.json
  and _md_exclude.txt (Phase 2 will rewrite swap_sources.py to produce
  these names; for now no swap script runs because overrides list is empty)

Phase 2 (next commit on this branch) will rewrite scripts/swap_sources.py
with inverted rename direction, delete scripts/import_myst.py + tests, and
update tests/test_swap_sources.py for the new semantics.

Phase 3 will be the cleanup pass and ready-for-review flip.

Generated by robots https://vyos.io

1 files changed, 119 insertions, 0 deletions

diff --git a/docs/configuration/interfaces/virtual-ethernet.md b/docs/configuration/interfaces/virtual-ethernet.md
new file mode 100644
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+++ b/docs/configuration/interfaces/virtual-ethernet.md
@@ -0,0 +1,119 @@
+---
+lastproofread: '2026-01-26'
+---
+
+(virtual-ethernet)=
+
+# Virtual Ethernet
+
+Virtual Ethernet (veth) interfaces are software-based interfaces that operate
+in pairs, creating a tunnel between each other. Traffic transmitted into one
+interface of the pair (e.g., `veth0`) is delivered directly to its peer
+interface (e.g., `veth1`).
+
+Veth interfaces are commonly used to connect network namespaces or VRFs, but
+they can also function as standalone virtual network interfaces.
+
+:::{note}
+Veth interfaces must be created in pairs, where each interface acts
+as the peer of the other.
+:::
+
+## Configuration
+
+### Common interface configuration
+
+```{cmdincludemd} /_include/interface-address-with-dhcp.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+```{cmdincludemd} /_include/interface-description.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+
+### VLAN
+
+#### Regular VLANs (802.1q)
+
+```{cmdincludemd} /_include/interface-vlan-8021q.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+
+#### 802.1ad (QinQ)
+
+```{cmdincludemd} /_include/interface-vlan-8021ad.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+```{cmdincludemd} /_include/interface-disable.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+```{cmdincludemd} /_include/interface-vrf.txt
+:var0: virtual-ethernet
+:var1: veth0
+```
+
+
+## Operation
+
+```{opcmd} show interfaces virtual-ethernet
+
+Show brief interface information.
+
+:::{code-block} none
+vyos@vyos:~$ show interfaces virtual-ethernet
+Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
+Interface        IP Address                        S/L  Description
+---------        ----------                        ---  -----------
+veth10           100.64.0.0/31                     u/u
+veth11           100.64.0.1/31                     u/u
+:::
+```
+
+```{opcmd} show interfaces virtual-ethernet \<interface\>
+
+Show detailed interface information.
+
+:::{code-block} none
+vyos@vyos:~$ show interfaces virtual-ethernet veth11
+10: veth11@veth10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master red state UP group default qlen 1000
+link/ether b2:7b:df:47:e9:11 brd ff:ff:ff:ff:ff:ff
+inet 100.64.0.1/31 scope global veth11
+valid_lft forever preferred_lft forever
+inet6 fe80::b07b:dfff:fe47:e911/64 scope link
+valid_lft forever preferred_lft forever
+
+RX:  bytes    packets     errors    dropped    overrun      mcast
+0          0          0          0          0          0
+TX:  bytes    packets     errors    dropped    carrier collisions
+1369707       4267          0          0          0          0
+:::
+```
+
+
+## Example
+
+The following example shows how to connect the global VRF to VRF ‘red ‘ using
+the `veth10` and `veth11` veth pair.
+
+```none
+set interfaces virtual-ethernet veth10 address '100.64.0.0/31'
+set interfaces virtual-ethernet veth10 peer-name 'veth11'
+set interfaces virtual-ethernet veth11 address '100.64.0.1/31'
+set interfaces virtual-ethernet veth11 peer-name 'veth10'
+set interfaces virtual-ethernet veth11 vrf 'red'
+set vrf name red table '1000'
+
+vyos@vyos:~$ ping 100.64.0.1
+PING 100.64.0.1 (100.64.0.1) 56(84) bytes of data.
+64 bytes from 100.64.0.1: icmp_seq=1 ttl=64 time=0.080 ms
+64 bytes from 100.64.0.1: icmp_seq=2 ttl=64 time=0.119 ms
+```