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Johnathan Corgan
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The arming check tested whether a dampening deadline had ever been set rather than whether one was still in effect, so the first episode disarmed the mechanism permanently. A node in a second flap storm went on switching parents under hold-down alone, and neither the flap_dampened counter nor the "Flap dampening engaged" warning fired again, so the storm was invisible to anyone watching that counter. Retire a lapsed episode explicitly, clearing both the deadline and the switch counter, so a second episode requires a fresh threshold of switches within one window rather than re-engaging on the first switch after lapse. Hold-down was unaffected throughout and continued to limit discretionary switching, which is why the practical effect at shipped settings was lost visibility and a lost escalation tier rather than unrestrained flapping. An episode engaged through the parent-ancestry update path now reports the counter and the warning as the other switch paths already did. One path remains silent, a re-engagement during parent-loss recovery, which runs inside the tree state where no metrics handle is reachable. Also cap node.tree.flap_dampening_secs at one year, so a value large enough to overflow the monotonic clock no longer panics the node when dampening engages. Report flap dampening engagement from every path that engages it One re-engagement path stayed silent, during parent-loss recovery, because it runs inside the tree state where no metrics handle is reachable. Return the fact of engagement to the caller that does have one, so every path that engages dampening reports the counter and the warning rather than most of them. Report dampening engagement without moving a published signature The observability change altered the return type of a published library function on the maintenance line, which would break a downstream caller at a patch release. Restore the signature and record the one path that stays silent as a known gap, which is what the design called for.
FIPS Design
Architectural and protocol-level explanations for FIPS — the why and the how behind the wire and the system. For wire formats and configuration keys, see reference/. For task recipes, see how-to/. For end-to-end lessons, see tutorials/.
Reading Order
Start with fips-concepts.md for the novice-friendly framing of what FIPS is and why, then move to fips-architecture.md for the protocol stack, identity model, and two-layer encryption walkthrough. From there, follow the protocol stack from bottom to top. After the stack, fips-mesh-operation.md explains how the pieces work together at runtime. Cross-cutting and supporting documents cover specific subsystems in detail.
Foundations
| Document | Description |
|---|---|
| fips-concepts.md | What FIPS is, why it exists, mental model |
| fips-architecture.md | Protocol stack, identity, two-layer encryption |
| fips-prior-work.md | Designs and protocols FIPS builds on |
Protocol Stack
| Document | Description |
|---|---|
| fips-transport-layer.md | Transport layer: datagram delivery over arbitrary media |
| fips-mesh-layer.md | FIPS Mesh Protocol (FMP): peer authentication, link encryption, forwarding |
| fips-session-layer.md | FIPS Session Protocol (FSP): end-to-end encryption, sessions |
| fips-ipv6-adapter.md | IPv6 adaptation: TUN interface, DNS, MTU enforcement |
Cross-Cutting
| Document | Description |
|---|---|
| fips-mmp.md | Metrics Measurement Protocol (link + session) |
| fips-mtu.md | Path MTU model, encapsulation overhead, PMTUD |
| fips-security.md | fips0 interface threat model and default-deny baseline |
Mesh Behavior
| Document | Description |
|---|---|
| fips-mesh-operation.md | How the mesh operates: routing, discovery, error recovery |
| fips-nostr-discovery.md | Optional Nostr-mediated peer discovery and UDP NAT hole-punch |
| port-advertisement-and-nat-traversal.md | Nostr-signaled port advertisement and UDP NAT-traversal protocol; generic, with FIPS as an example implementation |
Deeper Dives
| Document | Description |
|---|---|
| fips-spanning-tree.md | Spanning tree algorithms: root discovery, parent selection, coordinates |
| fips-bloom-filters.md | Bloom filter properties: FPR analysis, size classes, split-horizon |
| spanning-tree-dynamics.md | Spanning tree walkthroughs: convergence scenarios, worked examples |
Adjacent Components
| Document | Description |
|---|---|
| fips-gateway.md | fips-gateway service: outbound (LAN-to-mesh) DNS-proxy + virtual-IP NAT and inbound (mesh-to-LAN) port-forwarding, sharing one nftables table |