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Rayhaan JaufeerallyandClaude Fable 5.1 630c175918 Rework the speaker: sans-I/O FSM, sharded table, RFC 7606, ADD-PATH 
The work of the speaker-cleanup branch as one commit; the branch keeps
the step-by-step history.

Sessions
- The state machine is a pure function from events to actions, driven by
  one task per connection. Idle, Connect and Active belong to a dialer
  that keeps configured peers up with backoff.
- Capabilities are negotiated: address families, four-octet AS numbers
  with AS_TRANS and AS4_PATH, route refresh, ADD-PATH per family and
  direction.
- Collision detection per RFC 4271 section 6.8, by address and
  identifier.
- Connections are taken only from configured peers, a few per address.
- A panic in a session is contained and answered with a Cease; a core
  task that stops shuts the server down with a Cease to every peer.
- Writes that make no progress are given up (RFC 9687).

Codec
- Malformed UPDATEs are handled as RFC 7606 says: treat-as-withdraw,
  attribute discard, or session reset, with the NOTIFICATION to send.
- Address families are open types; any can be named and ignored.
- Prefixes are fixed-size values, normalised, with path identifiers.
- Lengths are filled in after writing; one definition of each type code.
- Property tests and fuzz targets for every decoder.

Routing table
- Adj-RIBs-In and Loc-RIB in one sharded table that sessions write to
  directly. Routes are sixteen bytes; attribute sets are interned in
  wire form. Best-path selection per RFC 4271 section 9.1.2.2 with
  deterministic MED.
- A journal per shard lets followers read changes at their own pace;
  one that falls behind is resynchronised.
- On a RIPE RIS dump of 148 peers and 39.3M routes: loaded in 2.0 s on
  12 cores, about 52 bytes a route.

Announcing
- Originated routes come from the configuration. Each session has its
  own exporter with an Adj-RIB-Out, so a slow peer delays only itself.
- Routes to a peer in our own AS have an empty path and a LOCAL_PREF.

Operations
- HTTP status page, JSON API, event stream and Prometheus metrics.
- Benchmarks on synthetic and real tables.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
2026-10-02 12:35:54 +02:00

5.7 KiB
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RFCs

Tracks which RFCs are implemented, partially implemented, or only represented in the wire format layer.

Legend

  • ✅ Implemented — functional end-to-end
  • 🟡 Wire format only — parsed and serialised correctly, but not yet acted on
  • ❌ Not implemented

Core BGP

RFC 4271 — A Border Gateway Protocol 4 (BGP-4)

https://datatracker.ietf.org/doc/html/rfc4271

The base protocol specification.

Section Description Status
§4.1 Message framing (marker, length, type) ✅
§4.2 OPEN message ✅
§4.3 UPDATE message (path attributes, NLRI, withdrawn routes) ✅
§4.4 KEEPALIVE message ✅
§4.5 NOTIFICATION message (all error codes and subcodes) ✅
§8 FSM — passive (inbound) side: OpenSent → OpenConfirm → Established ✅
§8 FSM — active (outbound) side: dial configured peers, exponential retry ✅
§6.2 Bad Peer AS check against configured ASN ✅
§6.7 / RFC 4486 Cease / Administrative Shutdown sent to every peer on SIGINT or SIGTERM ✅
§6.8 Connection collision detection (BGP Identifier comparison, Cease / Connection Collision Resolution) ✅
§8.1.1 Optional CollisionDetectEstablishedState (collision_detect_established_state) ✅
§6.2 Bad BGP Identifier check (peer using our identifier, or 0.0.0.0) ✅
§9 Decision process / best-path selection ❌
§9 Adj-RIB-In (per-peer table of received routes) ✅
§9 Locally originated routes, advertised to all established peers ✅
§9 Loc-RIB / Adj-RIB-Out for routes learned from peers (re-advertisement) ❌
§9.2 Hold timer reset on any received message (not only KEEPALIVE) ✅

Capability and Session Extensions

RFC 6793 — BGP Support for Four-Octet Autonomous System (AS) Number Space

https://datatracker.ietf.org/doc/html/rfc6793

Feature Status
AS_TRANS (23456) sentinel ✅
FourByteAsn capability advertisement and parsing ✅
4-byte AS_PATH segment encoding/decoding via ParserContext ✅
4-byte ASN negotiation in FSM ✅

RFC 9072 — Extended Optional Parameters Length for BGP OPEN Message

https://datatracker.ietf.org/doc/html/rfc9072

Feature Status
Parsing extended-length OPEN (0xFF sentinel) ✅
Serialising extended-length OPEN when options exceed 255 bytes ✅

RFC 2918 — Route Refresh Capability for BGP-4

https://datatracker.ietf.org/doc/html/rfc2918

Feature Status
RouteRefresh capability advertisement ✅
ROUTE-REFRESH message type (5) framing ✅
AFI/SAFI payload parsing ❌
Acting on received ROUTE-REFRESH (re-advertising all local routes, regardless of the AFI/SAFI asked for) ✅

RFC 7313 — Enhanced Route Refresh Capability for BGP-4

https://datatracker.ietf.org/doc/html/rfc7313

Feature Status
EnhancedRouteRefresh capability wire format 🟡

RFC 4724 — Graceful Restart Mechanism for BGP

https://datatracker.ietf.org/doc/html/rfc4724

Feature Status
GracefulRestart capability wire format 🟡
Restart state and forwarding preserved across sessions ❌

RFC 9494 — Long-Lived Graceful Restart for BGP

https://datatracker.ietf.org/doc/html/rfc9494

Feature Status
LongLivedGracefulRestart capability wire format 🟡

RFC 8654 — Extended Message Support for BGP

https://datatracker.ietf.org/doc/html/rfc8654

Feature Status
ExtendedMessage capability wire format 🟡
Raising BGP_MAX_MSG_LEN to 65535 when negotiated ❌

Multiprotocol and NLRI

RFC 2858 — Multiprotocol Extensions for BGP-4

https://datatracker.ietf.org/doc/html/rfc2858

Feature Status
MultiProtocol capability advertisement (IPv4 and IPv6 unicast) ✅
MP_REACH_NLRI path attribute (parse, serialise) ✅
MP_UNREACH_NLRI path attribute (parse, serialise) ✅
IPv4 and IPv6 next-hop encoding ✅

RFC 8950 — Advertising IPv4 Network Layer Reachability Information (NLRI) with an IPv6 Next Hop

https://datatracker.ietf.org/doc/html/rfc8950

Feature Status
ExtendedNextHop capability wire format 🟡

Path Attributes and Communities

RFC 1997 — BGP Communities Attribute

https://datatracker.ietf.org/doc/html/rfc1997

Feature Status
COMMUNITIES path attribute (parse, serialise) ✅
Attach to locally originated routes ✅

RFC 4360 — BGP Extended Communities Attribute

https://datatracker.ietf.org/doc/html/rfc4360

Feature Status
EXTENDED_COMMUNITIES path attribute (parse, serialise) ✅
AS-specific, IPv4-address-specific, opaque, route-target, route-origin subtypes ✅

RFC 8092 — BGP Large Communities Attribute

https://datatracker.ietf.org/doc/html/rfc8092

Feature Status
LARGE_COMMUNITIES path attribute (parse, serialise) ✅
Attach to locally originated routes ✅

Other Capabilities (Wire Format Only)

The following capabilities are parsed and serialised correctly but have no functional behaviour implemented beyond that.

RFC Capability Status
RFC 5291 Outbound Route Filtering (ORF) 🟡
RFC 7911 ADD-PATH 🟡
RFC 8205 BGPsec 🟡

Error Handling

RFC 9687 — BGP Send Hold Timer

https://datatracker.ietf.org/doc/html/rfc9687

Feature Status
SendHoldTimer error code (8) defined ✅
Send hold timer enforcement ❌
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