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, 277 insertions, 0 deletions

diff --git a/docs/configexamples/segment-routing-isis.md b/docs/configexamples/segment-routing-isis.md
new file mode 100644
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@@ -0,0 +1,277 @@
+---
+lastproofread: '2023-04-10'
+---
+
+(examples-segment-routing-isis)=
+
+# Segment-routing IS-IS example
+
+When utilizing VyOS in an environment with Cisco IOS-XR gear you can use this
+blue print as an initial setup to get MPLS ISIS-SR working between those two
+devices.The lab was build using {abbr}`EVE-NG (Emulated Virtual
+Environment NG)`.
+
+:::{figure} /_static/images/vyos-sr-isis.webp
+:alt: ISIS-SR network
+
+ISIS-SR example network
+:::
+
+The below configuration is used as example where we keep focus on
+VyOS-P1/VyOS-P2/XRv-P3 which we share the settings.
+
+## Configuration
+
+- VyOS-P1:
+
+```none
+set interfaces dummy dum0 address '192.0.2.1/32'
+set interfaces ethernet eth1 address '192.0.2.5/30'
+set interfaces ethernet eth1 mtu '8000'
+set interfaces ethernet eth3 address '192.0.2.21/30'
+set interfaces ethernet eth3 mtu '8000'
+set protocols isis interface dum0 passive
+set protocols isis interface eth1 network point-to-point
+set protocols isis interface eth3 network point-to-point
+set protocols isis level 'level-2'
+set protocols isis log-adjacency-changes
+set protocols isis metric-style 'wide'
+set protocols isis net '49.0000.0000.0000.0001.00'
+set protocols isis segment-routing maximum-label-depth '8'
+set protocols isis segment-routing prefix 192.0.2.1/32 index value '1'
+set protocols mpls interface 'eth1'
+set protocols mpls interface 'eth3'
+set system host-name 'P1-VyOS'
+```
+
+- XRv-P3:
+
+```none
+hostname P3-VyOS
+interface Loopback0
+ ipv4 address 192.0.2.3 255.255.255.255
+!
+interface GigabitEthernet0/0/0/1
+ mtu 8014
+ ipv4 address 192.0.2.6 255.255.255.252
+!
+interface GigabitEthernet0/0/0/2
+ mtu 8014
+ ipv4 address 192.0.2.18 255.255.255.252
+!
+router isis VyOS
+ is-type level-2-only
+ net 49.0000.0000.0000.0003.00
+ log adjacency changes
+ address-family ipv4 unicast
+  metric-style wide
+  segment-routing mpls
+ !
+ interface Loopback0
+  passive
+  address-family ipv4 unicast
+   prefix-sid index 3
+  !
+ !
+ interface GigabitEthernet0/0/0/1
+  point-to-point
+  address-family ipv4 unicast
+  !
+ !
+ interface GigabitEthernet0/0/0/2
+  point-to-point
+  address-family ipv4 unicast
+  !
+ !
+!
+```
+
+- VyOS-P2:
+
+```none
+set interfaces dummy dum0 address '192.0.2.2/32'
+set interfaces ethernet eth2 address '192.0.2.17/30'
+set interfaces ethernet eth2 mtu '8000'
+set interfaces ethernet eth3 address '192.0.2.26/30'
+set interfaces ethernet eth3 mtu '8000'
+set protocols isis interface dum0 passive
+set protocols isis interface eth2 network point-to-point
+set protocols isis interface eth3 network point-to-point
+set protocols isis level 'level-2'
+set protocols isis log-adjacency-changes
+set protocols isis metric-style 'wide'
+set protocols isis net '49.0000.0000.0000.0002.00'
+set protocols isis segment-routing maximum-label-depth '8'
+set protocols isis segment-routing prefix 192.0.2.2/32 index value '2'
+set protocols mpls interface 'eth2'
+set protocols mpls interface 'eth3'
+set system host-name 'P2-VyOS'
+```
+
+This gives us MPLS segment routing enabled and labels forwarding :
+
+```none
+vyos@P1-VyOS:~$ show mpls table
+Inbound Label  Type        Nexthop               Outbound Label
+-----------------------------------------------------------------
+15000          SR (IS-IS)  192.0.2.6             implicit-null
+15001          SR (IS-IS)  192.0.2.22            implicit-null
+15002          SR (IS-IS)  fe80::5200:ff:fe04:3  implicit-null
+16002          SR (IS-IS)  192.0.2.6             16002
+16003          SR (IS-IS)  192.0.2.6             implicit-null
+16011          SR (IS-IS)  192.0.2.22            implicit-null
+
+vyos@P2-VyOS:~$ show mpls table
+Inbound Label  Type        Nexthop     Outbound Label
+-------------------------------------------------------
+15000          SR (IS-IS)  192.0.2.18  implicit-null
+16001          SR (IS-IS)  192.0.2.18  16001
+16003          SR (IS-IS)  192.0.2.18  implicit-null
+16011          SR (IS-IS)  192.0.2.18  16011
+
+RP/0/0/CPU0:P3-VyOS#show mpls forwarding
+Tue Mar 28 17:47:18.928 UTC
+Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes
+Label  Label       or ID              Interface                    Switched
+------ ----------- ------------------ ------------ --------------- ------------
+16001  Pop         SR Pfx (idx 1)     Gi0/0/0/1    192.0.2.5       0
+16002  Pop         SR Pfx (idx 2)     Gi0/0/0/2    192.0.2.17      0
+16011  16011       SR Pfx (idx 11)    Gi0/0/0/1    192.0.2.5       0
+24000  Pop         SR Adj (idx 1)     Gi0/0/0/1    192.0.2.5       0
+24001  Pop         SR Adj (idx 3)     Gi0/0/0/1    192.0.2.5       0
+24002  Pop         SR Adj (idx 1)     Gi0/0/0/2    192.0.2.17      0
+24003  Pop         SR Adj (idx 3)     Gi0/0/0/2    192.0.2.17      0
+```
+
+VyOS is able to check MSD per devices:
+
+```none
+vyos@P1-VyOS:~$ show isis segment-routing node
+Area VyOS:
+IS-IS L1 SR-Nodes:
+
+IS-IS L2 SR-Nodes:
+
+System ID       SRGB           SRLB            Algorithm  MSD
+---------------------------------------------------------------
+0000.0000.0001  16000 - 23999  15000 - 15999   SPF        8
+0000.0000.0002  16000 - 23999  15000 - 15999   SPF        8
+0000.0000.0003  16000 - 23999  0 - 4294967295  SPF        10
+0000.0000.0011  16000 - 23999  15000 - 15999   SPF        8
+
+vyos@P2-VyOS:~$ show isis segment-routing node
+Area VyOS:
+ IS-IS L1 SR-Nodes:
+
+ IS-IS L2 SR-Nodes:
+
+ System ID       SRGB           SRLB            Algorithm  MSD
+ ---------------------------------------------------------------
+ 0000.0000.0001  16000 - 23999  15000 - 15999   SPF        8
+ 0000.0000.0002  16000 - 23999  15000 - 15999   SPF        8
+ 0000.0000.0003  16000 - 23999  0 - 4294967295  SPF        10
+ 0000.0000.0011  16000 - 23999  15000 - 15999   SPF        8
+```
+
+Here is the routing tables showing the MPLS segment routing label operations:
+
+```none
+vyos@P1-VyOS:~$ show ip route isis
+Codes: K - kernel route, C - connected, S - static, R - RIP,
+       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+       T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+       f - OpenFabric,
+       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+       t - trapped, o - offload failure
+
+I>* 192.0.2.2/32 [115/30] via 192.0.2.6, eth1, label 16002, weight 1, 1d03h18m
+I>* 192.0.2.3/32 [115/10] via 192.0.2.6, eth1, label implicit-null, weight 1, 1d03h18m
+I   192.0.2.4/30 [115/20] via 192.0.2.6, eth1 inactive, weight 1, 1d03h18m
+I>* 192.0.2.11/32 [115/20] via 192.0.2.22, eth3, label implicit-null, weight 1, 1d02h47m
+I>* 192.0.2.16/30 [115/20] via 192.0.2.6, eth1, weight 1, 1d03h18m
+I   192.0.2.20/30 [115/20] via 192.0.2.22, eth3 inactive, weight 1, 1d02h48m
+I>* 192.0.2.24/30 [115/30] via 192.0.2.6, eth1, weight 1, 1d03h18m
+
+
+vyos@P2-VyOS:~$ show ip route isis
+Codes: K - kernel route, C - connected, S - static, R - RIP,
+       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
+       T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
+       f - OpenFabric,
+       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
+       t - trapped, o - offload failure
+
+I>* 192.0.2.1/32 [115/30] via 192.0.2.18, eth2, label 16001, weight 1, 1d03h17m
+I>* 192.0.2.3/32 [115/10] via 192.0.2.18, eth2, label implicit-null, weight 1, 1d03h17m
+I>* 192.0.2.4/30 [115/20] via 192.0.2.18, eth2, weight 1, 1d03h17m
+I>* 192.0.2.11/32 [115/40] via 192.0.2.18, eth2, label 16011, weight 1, 1d02h47m
+I   192.0.2.16/30 [115/20] via 192.0.2.18, eth2 inactive, weight 1, 1d03h17m
+I>* 192.0.2.20/30 [115/30] via 192.0.2.18, eth2, weight 1, 1d03h17m
+
+RP/0/0/CPU0:P3-VyOS#show route isis
+Tue Mar 28 18:19:16.417 UTC
+
+i L2 192.0.2.1/32 [115/20] via 192.0.2.5, 1d03h, GigabitEthernet0/0/0/1
+i L2 192.0.2.2/32 [115/20] via 192.0.2.17, 1d03h, GigabitEthernet0/0/0/2
+i L2 192.0.2.11/32 [115/30] via 192.0.2.5, 1d02h, GigabitEthernet0/0/0/1
+i L2 192.0.2.20/30 [115/20] via 192.0.2.5, 1d03h, GigabitEthernet0/0/0/1
+i L2 192.0.2.24/30 [115/20] via 192.0.2.17, 1d03h, GigabitEthernet0/0/0/2
+```
+
+Information about prefix-sid and label-operation from VyOS
+
+```none
+vyos@P1-VyOS:~$ show isis route prefix-sid
+Area VyOS:
+IS-IS L2 IPv4 routing table:
+
+ Prefix         Metric  Interface  Nexthop    SID  Label Op.
+ ----------------------------------------------------------------------
+ 192.0.2.1/32   0       -          -          -    -
+ 192.0.2.2/32   30      eth1       192.0.2.6  2    Swap(16002, 16002)
+ 192.0.2.3/32   10      eth1       192.0.2.6  3    Pop(16003)
+ 192.0.2.4/30   20      eth1       192.0.2.6  -    -
+ 192.0.2.16/30  20      eth1       192.0.2.6  -    -
+ 192.0.2.20/30  0       -          -          -    -
+ 192.0.2.24/30  30      eth1       192.0.2.6  -    -
+
+ vyos@P2-VyOS:~$ show isis route prefix-sid
+ Area VyOS:
+ IS-IS L2 IPv4 routing table:
+
+  Prefix         Metric  Interface  Nexthop     SID  Label Op.
+  -----------------------------------------------------------------------
+  192.0.2.1/32   30      eth2       192.0.2.18  1    Swap(16001, 16001)
+  192.0.2.2/32   0       -          -           -    -
+  192.0.2.3/32   10      eth2       192.0.2.18  3    Pop(16003)
+  192.0.2.4/30   20      eth2       192.0.2.18  -    -
+  192.0.2.16/30  20      eth2       192.0.2.18  -    -
+  192.0.2.20/30  30      eth2       192.0.2.18  -    -
+  192.0.2.24/30  0       -          -           -    -
+```
+
+Ping between VyOS-P1 / VyOS-P2 to confirm reachability:
+
+```none
+vyos@P1-VyOS:~$ ping 192.0.2.2 source-address 192.0.2.1
+PING 192.0.2.2 (192.0.2.2) from 192.0.2.1 : 56(84) bytes of data.
+64 bytes from 192.0.2.2: icmp_seq=1 ttl=63 time=3.47 ms
+64 bytes from 192.0.2.2: icmp_seq=2 ttl=63 time=2.06 ms
+64 bytes from 192.0.2.2: icmp_seq=3 ttl=63 time=3.90 ms
+64 bytes from 192.0.2.2: icmp_seq=4 ttl=63 time=3.87 ms
+^C
+--- 192.0.2.2 ping statistics ---
+4 packets transmitted, 4 received, 0% packet loss, time 3004ms
+rtt min/avg/max/mdev = 2.064/3.326/3.903/0.748 ms
+
+vyos@P2-VyOS:~$ ping 192.0.2.1 source-address 192.0.2.2
+PING 192.0.2.1 (192.0.2.1) from 192.0.2.2 : 56(84) bytes of data.
+64 bytes from 192.0.2.1: icmp_seq=1 ttl=63 time=2.91 ms
+64 bytes from 192.0.2.1: icmp_seq=2 ttl=63 time=3.23 ms
+64 bytes from 192.0.2.1: icmp_seq=3 ttl=63 time=2.91 ms
+64 bytes from 192.0.2.1: icmp_seq=4 ttl=63 time=2.85 ms
+^C
+--- 192.0.2.1 ping statistics ---
+4 packets transmitted, 4 received, 0% packet loss, time 3005ms
+rtt min/avg/max/mdev = 2.846/2.972/3.231/0.151 ms
+```