ferrix/docs/content/docs/reference/rfcs.md

+++ title = "Supported Standards" description = "Lists the RFCs and Internet-Drafts that Ferrix supports, and the implementation status of each feature." weight = 5

[extra] nav = "Supported Standards" +++

This topic lists the RFCs and Internet-Drafts that Ferrix supports, and the implementation status of each feature. Table 1 describes the status values.

Status	Meaning
✅	Supported.
🟡	Encoded and decoded only. Ferrix parses and generates the element but does not act on it.
❌	Not supported.

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§4.3	UPDATE message (path attributes, NLRI, withdrawn routes)	✅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 (neighbor uses the local identifier, or 0.0.0.0)	✅
§9	Decision process / best-path selection	✅
§9.1.2	Best routes installed for forwarding (Linux kernel, over netlink), where the next hop is directly connected	✅
§9.1.2.1	Routes with an unresolvable next hop excluded from selection	✅ where routes are installed in the kernel: such a route is held out of the table until its next hop can be reached
§9.1.2.1	Next hops resolved through other routes	❌ (only next hops that are neighbors count as reachable)
§9	Adj-RIB-In (per-peer table of received routes)	✅
§9	Locally originated routes, advertised to all established peers	✅
§9	Advertisement of the best path for each prefix to neighbors (export.learned_routes), with the local AS prepended and the local address as next hop; MED and LOCAL_PREF not sent to EBGP neighbors; LOCAL_PREF sent to IBGP neighbors (§5.1.4, §5.1.5, §9.1.3)	✅
§9.2.1	Routes learned from an IBGP neighbor not advertised to other IBGP neighbors (no route reflection)	✅
§9.1.3	Routes not advertised to a neighbor whose AS is in the AS path	✅
§5	Unknown optional transitive attributes advertised with the Partial bit set; unknown non-transitive attributes not advertised	✅
§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	✅
AS4_PATH from a two-octet peer merged into AS_PATH on receipt (§4.2.3); one longer than AS_PATH ignored	✅

RFC 9774 — Deprecation of AS_SET and AS_CONFED_SET in BGP

https://datatracker.ietf.org/doc/html/rfc9774

Feature	Status
Routes with an AS_SET in the AS path rejected on import (configurable with accept_as_sets)	✅
AS_SET never sent	✅

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	✅
Received ROUTE-REFRESH processed by readvertising all routes for the session, for all AFI/SAFIs	✅

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 offered on sessions over IPv6 that carry IPv4 unicast, and used if the peer offers it	✅
IPv4 unicast routes advertised and withdrawn in MP_REACH_NLRI / MP_UNREACH_NLRI with the local IPv6 address as next hop	✅
IPv4 unicast routes received with an IPv6 next hop (global, or global and link-local)	✅
Such routes installed in the kernel (IPv4 route by way of an IPv6 neighbor)	✅
Other families than IPv4 unicast (VPN-IPv4, labelled)	❌
Sessions between link-local addresses (fe80::1%eth0), with link-local next hops	✅

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	✅
NO_EXPORT, NO_EXPORT_SUBCONFED, and NO_ADVERTISE observed when learned routes are advertised	✅
Communities added and removed by import and export policy	✅

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 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 (a write that makes no progress ends the session)	✅

Route Security

RFC 6811 — BGP Prefix Origin Validation

https://datatracker.ietf.org/doc/html/rfc6811

Feature	Status
Validation states (valid, invalid, not found) for routes from external peers	✅
Invalid routes rejected, per neighbor (configurable with accept_rpki_invalid)	✅
Routes revalidated when the VRPs change, in both directions	✅
Validation of routes from internal peers and of originated routes	❌
Validity as a step of route selection (RFC 8097 communities)	❌

draft-ietf-sidrops-aspa-verification — BGP AS_PATH Verification Based on ASPA

https://datatracker.ietf.org/doc/draft-ietf-sidrops-aspa-verification/

Implemented from version 24 of the draft.

Feature	Status
Upstream verification (routes from customers, peers, route servers and route server clients)	✅
Downstream verification (routes from providers)	✅
Per-peer role (role); paths of peers without one are not verified	✅
Invalid paths rejected, per neighbor (configurable with accept_aspa_invalid)	✅
Routes revalidated when the ASPAs change, in both directions	✅
Paths with an AS_SET invalid	✅
Verification on export	❌ (the AS paths of advertised routes are not verified)

RFC 7947 — Internet Exchange BGP Route Server

https://datatracker.ietf.org/doc/html/rfc7947

Feature	Status
§2.2.1 / §2.2.2: to a ROUTE_SERVER_CLIENT the path is not prepended and the next hop and MED are left as they came	✅
§2.2.2.2 / §4.6: communities with which a client restricts the advertisement of its routes to other clients (control_communities)	✅
Per-client best path selection (a different best route for each client)	❌ (every client receives the same best path)

RFC 9234 — Route Leak Prevention and Detection Using Roles in UPDATE and OPEN Messages

https://datatracker.ietf.org/doc/html/rfc9234

Feature	Status
BGP Role capability sent for peers with a configured role	✅
Role Mismatch (OPEN Message Error, subcode 11) when the neighbor's role does not correspond to the local role, or the neighbor advertises conflicting roles	✅
Strict mode (require_role)	✅
Only to Customer attribute: parse, serialise, treat-as-withdraw when malformed	✅
Ingress: routes with OTC rejected from customers, route server clients, and (unless the OTC value is the peer's AS) peers	✅
Ingress: routes from providers, peers and route servers marked	✅
Egress: originated routes to customers, peers and route server clients marked	✅
Egress: marked routes not sent to providers, peers or route servers	✅

RFC 8210 — The RPKI to Router Protocol, Version 1 (RFC 6810, version 0; draft-ietf-sidrops-8210bis, version 2)

https://datatracker.ietf.org/doc/html/rfc8210

Version 2 is implemented from version 23 of the draft.

Feature	Status
Reset and serial queries, notifies, cache reset, incremental updates	✅
Refresh, retry and expire intervals; data dropped when it expires	✅
Version 2, with fallback to 1 and 0; several caches with failover	✅
ASPA PDU (version 2)	✅
Error Reports sent to the cache	✅
Version 2's ordering of PDUs enforced on what a cache sends	❌ (PDUs are accepted in any order)
Transport over plain TCP	✅
Transport over SSH, TLS, TCP-MD5 or TCP-AO	❌
Router keys (BGPsec)	🟡 read and ignored

RFC 7911 — Advertisement of Multiple Paths in BGP (ADD-PATH)

https://datatracker.ietf.org/doc/html/rfc7911

Feature	Status
Capability negotiation per family and direction	✅
Receiving several routes for a prefix	✅
Sending several routes for a prefix	❌ (path identifiers are sent; one route each)

RFC 4271 §9.1.2 / RFC 4486 / operational practice — import policy

Feature	Status
Routes with the local AS in the AS path rejected (loop detection)	✅
Bogon prefixes and AS numbers, prefix length bounds, first-AS check	✅
Per-peer prefix and origin AS allow-lists	✅
Maximum prefixes with Cease / Maximum Number of Prefixes Reached and hold-down	✅