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lab/migration/pulumi-override-he-tunnel-both.json
Michal 395577850c
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IPv6 was never HA, and the WAN becoming HA is what exposed it
Reviewed the parked IPv6 task against the PPPoE-HA work of 2026-09-05/06. The
gate that parked it ("WI-8 before IPv6") is cleared, but the same work
invalidated the assumption the IPv6 design rested on.

Verified on the live routers: vyos002 has no tun0, no he-tunnel-follow, no
he-secrets, no VLAN 9 prefix and no route6 ::/0 -- only the pre-staged
default-deny v6 firewall, which is correctly on both. Failover is now automatic
and drill-proven, so every failover takes the whole v6 estate down for as long
as vyos002 holds the VIP.

Four things that came out of checking rather than reading:

- PPPOE-HA.md's "tun0 survived untouched and IPv6 stayed up at 15.5ms" does not
  follow from its own premise and is corrected in place. The endpoint address is
  stable, but it MOVES to vyos002, which has nothing to decapsulate protocol 41.
  wan-drill had no IPv6 check at all, which is why nobody caught it.
- A 22-second near-miss: vif53-pin-boot-disable bounced the 10 gig, he-tunnel-
  follow ticked once and saw the PPPoE address, and vyos-failover restored the
  route 22s before the second tick would have pointed HE at an address Vodafone
  reissues on every dial.
- VyOS does NOT leave a tunnel down when its source-address is absent (the
  override's stated reason for leaving IPv6 single-homed). Measured in labsim:
  it commits rc=0 and brings the link UP -- a blackhole that attracts the v6
  default route. The runtime gate is load-bearing, like the PPPoE gate.
- The RA link-mtu was pinned at 1480 while the tunnel correctly drops to 1472 on
  the PPPoE path.

Mechanism, mirroring PPPoE HA -- identical config on both, gated at runtime, no
commit in the failover path:

- vrrp-wan-reconcile: a v6 kernel plane. tun0 and radvd follow the VIP; radvd is
  stopped BEFORE the WAN goes so its farewell RA (router-lifetime 0) still has a
  path out. The WAN early-exits became if-blocks so the plane runs every tick.
  It deliberately does NOT call he-tunnel-follow: that would halve the
  hysteresis the near-miss above showed we depend on.
- he-tunnel-follow: a master guard reading the same vrrp-wan.conf VIP, so the
  backup copy cannot point HE at its own idle PPPoE line, plus a stubbable
  HE_UPDATE_URL.
- vrrp-wan-install carries both, so --check and the upgrade runbook cover IPv6.
- wan-drill measures IPv6 in both timing loops and asserts zero HE API calls
  across a router failover.

labsim finally has an HE endpoint, closing the gap the override itself cited as
why this was never rehearsed. Both ISP islands already share the libvirt network,
so that becomes the backbone and HE lives behind it on one address reachable over
either WAN. Proven in the sim: backup tun=DOWN radvd=inactive, master tun=UP
radvd=active, hysteresis then HE call then MTU 1480->1472, and VLAN 9 hosts
autoconfiguring from the RA. The end-to-end v6 datapath is NOT yet proven --
inter-island transit crosses libvirt NAT and the return path is lost. Recorded as
a KNOWN SIM GAP rather than papered over.

The model change is staged, not merged: another agent runs pulumi up on that
repo, and the gate must exist on vyos002 before the tunnel does.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
2026-09-06 14:30:44 +01:00

188 lines
7.3 KiB
JSON

{
"id": "he-ipv6-tunnel",
"reason": "6in4 tunnel to Hurricane Electric, bringing 2001:470:187e::/48 in, on BOTH routers. SUPERSEDES he-ipv6-tunnel-vyos001, whose reason said 'vyos002 carries bond0.53 disabled, so the source address does not exist there and the tunnel would simply stay down -- adding it there is for a later takeover story, not now.' Both halves of that expired on 2026-09-06. `vif 53 disable` is no longer a property of vyos002: it is RUNTIME state owned by vrrp-wan-reconcile, keyed on who holds the management VIP, and deliberately absent from this model (see pppoe-gated-not-config-disabled and PPPOE-HA.md). And the takeover story shipped -- a drill moved the WAN and back, 52s and 36s. IPv6 did not follow it, so every failover took the whole v6 estate down for as long as vyos002 held the VIP. WHY THIS IS CHEAP: 87.192.101.48 is the 10 gig lease bound to the cloned MAC, and the drill proved the ISP re-issues THE SAME address to that MAC on the other router's port. The tunnel endpoint is therefore stable across the pair, so a router-level failover needs no HE API call at all -- only the tunnel present on both boxes and live on exactly one. HE updates remain solely for the within-box fall back to PPPoE, which /config/he-tunnel-follow already handles. WHY THE RUNTIME GATE IS LOAD-BEARING, not a nicety: measured in labsim 2026-09-06, VyOS ACCEPTS a tunnel whose source-address does not exist on the box (commit rc=0) and brings the link UP anyway. It is a blackhole that will happily attract the v6 default route -- not the inert node the old reason assumed. vrrp-wan-reconcile holds tun0 down on the backup and brings it up on the master, at kernel level, with no commit in the failover path. Verified in the sim: backup tun=DOWN radvd=inactive, master tun=UP radvd=active. MTU 1480, not 1500: 6in4 adds a 20-byte outer IPv4 header. Leave it at 1500 and IPv6 appears to work while large transfers hang. The RA link-mtu is 1472 -- the PPPoE figure -- deliberately, on BOTH routers: it cannot be reconciled at runtime because it needs a commit, so advertise the lower of the two paths and be correct on either WAN. Production previously pinned 1480 and was silently wrong whenever the WAN fell back. bond0.9 takes ::1 on vyos001 and ::2 on vyos002 -- NOT the same address: SLAAC hosts take their gateway from the advertising router's link-local, so the global address need not move, and duplicating it would only produce a DAD conflict. default-preference is high on vyos001 and low on vyos002 so that if both ever advertise at once -- radvd's config is rendered into /run and a booting backup starts it before VRRP has decided -- hosts prefer the normal master, while a genuinely dead vyos001 still leaves vyos002 as the only router on the link. No firewall change is needed: the IPv6 firewall accepts only from interface-group LAN, so tun0 is untrusted by default. It is already default-deny on BOTH routers -- that ordering held. REHEARSAL: labsim/labsim-he-endpoint.sh now builds a fake HE endpoint and stub tunnelbroker API, closing the 'the sim has no public IPv4 and no HE endpoint' gap the old reason cited as why this was never tested. labsim/labsim-ipv6-ha-test.sh is the matrix. Mechanism proven there; the end-to-end v6 datapath is not yet, because the sim's inter-island transit crosses libvirt NAT -- see that file's KNOWN SIM GAP header.",
"set": [
{
"path": [
"interfaces",
"tunnel",
"tun0",
"encapsulation"
],
"value": "sit"
},
{
"path": [
"interfaces",
"tunnel",
"tun0",
"source-address"
],
"value": "87.192.101.48"
},
{
"path": [
"interfaces",
"tunnel",
"tun0",
"remote"
],
"value": "216.66.88.98"
},
{
"path": [
"interfaces",
"tunnel",
"tun0",
"address"
],
"value": "2001:470:1f1c:f6::2/64"
},
{
"path": [
"interfaces",
"tunnel",
"tun0",
"mtu"
],
"value": "1480"
},
{
"path": [
"interfaces",
"tunnel",
"tun0",
"description"
],
"value": "HE 6in4 tunnel - 2001:470:187e::/48"
},
{
"path": [
"protocols",
"static",
"route6",
"::/0",
"next-hop",
"2001:470:1f1c:f6::1"
],
"value": {}
},
{
"path": [
"system",
"task-scheduler",
"task",
"he-tunnel-follow",
"executable",
"path"
],
"value": "/config/he-tunnel-follow"
},
{
"path": [
"system",
"task-scheduler",
"task",
"he-tunnel-follow",
"executable",
"arguments"
],
"value": "run"
},
{
"path": [
"system",
"task-scheduler",
"task",
"he-tunnel-follow",
"interval"
],
"value": "1m"
}
],
"perRouter": {
"vyos001": [
{
"path": [
"interfaces",
"bonding",
"bond0",
"vif",
"9",
"address"
],
"value": "2001:470:187e:9::1/64"
},
{
"path": [
"service",
"router-advert",
"interface",
"bond0.9",
"default-preference"
],
"value": "high"
}
],
"vyos002": [
{
"path": [
"interfaces",
"bonding",
"bond0",
"vif",
"9",
"address"
],
"value": "2001:470:187e:9::2/64"
},
{
"path": [
"service",
"router-advert",
"interface",
"bond0.9",
"default-preference"
],
"value": "low"
}
]
},
"sharedRouterAdvert": [
{
"path": [
"service",
"router-advert",
"interface",
"bond0.9",
"link-mtu"
],
"value": "1472"
},
{
"path": [
"service",
"router-advert",
"interface",
"bond0.9",
"prefix",
"2001:470:187e:9::/64",
"preferred-lifetime"
],
"value": "604800"
},
{
"path": [
"service",
"router-advert",
"interface",
"bond0.9",
"prefix",
"2001:470:187e:9::/64",
"valid-lifetime"
],
"value": "2592000"
}
],
"_staging_note": "STAGED, NOT MERGED -- on purpose, exactly like migration/pulumi-override-pppoe-gated.json was. Another agent runs `pulumi up` on kubernetes-deployment, so merging this IS a production change made by someone else at a time you do not choose. Order of operations, and it matters: (1) place /config/he-secrets on vyos002 and run migration/vrrp-wan-install on BOTH routers, so the runtime gate that holds tun0 down exists there BEFORE the tunnel does; (2) run `npm run vyos:export && npm run vyos:render` immediately before merging, so the model follows whichever router actually holds the WAN; (3) merge. Reversed, vyos002 gets a tunnel with no gate and an UP blackhole interface that attracts the v6 default route. The perRouter/sharedRouterAdvert shape here is descriptive -- fold it into whatever form overrides.json actually supports for per-router values when merging; the vyos001-only precedent is the `routers` key."
}