# 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| §4.3 | UPDATE message (path attributes, NLRI, withdrawn routes) | ✅ |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: Idle → Connect → Active | ❌ |
| §9 | Decision process / best-path selection | ❌ |
| §9 | RIB (Adj-RIB-In, Loc-RIB, Adj-RIB-Out) | ❌ |

---

## 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 routes) | ❌ |

### 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 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) | ✅ |

### 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) | ✅ |

---

## 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 | ❌ |