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2 Commits
| Author | SHA1 | Message | Date | |
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Michal
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395577850c |
IPv6 was never HA, and the WAN becoming HA is what exposed it
Some checks failed
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
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Michal
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4efd70c987 |
vyos: move PPPoE off the config plane onto a gated systemd unit
Some checks failed
PPPoE HA could not work as written, and the reason is structural rather than a
bug: `set interfaces pppoe pppoe0 disable` and `delete` are handled identically
by interfaces_pppoe.py -- both UNLINK /etc/ppp/peers/pppoe0. That path is pppd's
own options file, so the resting state destroyed exactly what the promotion path
needed, and `ppp@pppoe0` restart-looped against it (observed: 47 restarts, zero
sessions at the access concentrator). It also made op-mode `connect interface
pppoe0` unusable, and put every failover behind a priority-322 commit where one
unrelated invalid node fails the whole thing -- which has already taken the
10 gig down once.
pppoe0 is now configured identically and ENABLED on both routers, so the peers
file always exists, and dialling is gated by a drop-in on the unit:
ConditionPathExists=/run/vrrp-wan/may-dial
ConditionPathExists=/etc/ppp/peers/pppoe0
/run is tmpfs, so the gate is shut at boot and neither box can dial before VRRP
has decided. That matters more than it first appears: with the node enabled,
interfaces_pppoe.py restarts ppp on EVERY commit touching the pppoe subtree when
the daemon is not running -- so the backup actively tries to dial whenever
anything commits. The gate is the only thing making that a no-op, which is why
vrrp-wan-reconcile now refuses to bless a box whose drop-in is missing: /etc is
per-image, and a VyOS upgrade would otherwise silently remove the protection.
may-dial is a LEASE, not a flag. ConditionPathExists is evaluated at start only
-- it can prevent a dial, never revoke one -- so a reconciler that stops running
while its box is demoted would keep the one ISP session for ever. The reconciler
renews the lease; a new 5s vrrp-wan-guard revokes it, and only ever revokes. It
fired correctly first time: "GUARD: lease stale (81s > 75s)".
Also: remove-then-stop on release (the file's absence blocks a NEW start that a
concurrent commit would trigger); a flap damper, because two routers that both
believe they hold the VIP will both dial and each dial kills the other's session
-- against a real ISP that is how an account gets rate-limited; and a guard on
`cfg` returning empty under commit-lock contention, which had already produced
one spurious "releasing" on a box that needed nothing.
GRACE 90 -> 180. accel-ppp's dead-peer budget is lcp-echo-interval(30) x
failure(3) = 90s, so the old value sat exactly on the boundary: a hard failover
into an AC that does not replace the stale session would fail its own check,
shed the VIPs, and leave both routers in FAULT.
The sim could not have tested any of this. Both routers now get the identical
WAN -- the secondary had none "because two PPPoE clients sharing one credential
is a different failure mode than anything production has", which is backwards:
that IS production. It also left the pair incomparable, ten NAT rules against
none. Safety now comes from resting state, not asymmetry.
Three more things the sim was hiding:
- the drift check's secondary regex omitted interfaces pppoe/bonding, nat
source and protocols failover, so it reported "in sync" for a box with no
WAN at all;
- the VRRP health-check and transition-script hooks existed on both live VMs
and in NEITHER generator -- the mechanism under test was pure undetected
drift;
- labsim-vyos's only default route was the libvirt-NAT scaffold, so every
"the LAN still has internet" verdict on it was answered by eth2 rather than
the WAN. --drop-scaffold applied; the earlier DHCP-failover proof is being
re-run because of it.
vrrp-wan-install ends the other half of that: the sim's previous proof came from
scripts hand-`sed`-ed in place, so the tested behaviour was not the committed
behaviour. `--check` now makes that a hard failure.
First green run: master holds both WANs, backup released, and the AC reports
exactly ONE session. sim-net-apply.sh check: all four in sync.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
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