A peer's endpoint may be a link-local IPv6 address with the interface it
is on. Such a peer is the address and the interface together, wherever
peers are told apart: admission, collisions, hold-downs, the refusal log,
the status page. The interface is looked up by name each time it is
needed, so one that appears later or is made anew is found.
Our routes go out with our link-local address in both places of
MP_REACH_NLRI's next hop, as FRR sends its own. A peer's link-local next
hop is taken alone, twice, or after "::" (BIRD), and resolved in the
kernel on the interface of the session rather than by looking fe80::/64
up, which every interface has.
The lab has a new phase, linklocal: sessions with FRR (by interface, with
radvd beside the daemon) and BIRD over a LAN with link-local addresses
only, both families, pings across, the interface down and up.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
For a link that has only IPv6 addresses.
- The Extended Next Hop capability is offered on every session over IPv6
whose families include IPv4 unicast, and used if the peer offers it too.
Nothing to configure.
- On such a session our IPv4 routes go out in MP_REACH_NLRI with the
session's IPv6 address as next hop, and are withdrawn in
MP_UNREACH_NLRI. Without the agreement they are not sent, as before.
- IPv4 routes are read with an IPv6 next hop, global or global with
link-local.
- The kernel installer resolves an IPv4 route's IPv6 next hop like any
other and installs it: by way of an IPv6 nexthop object, or with RTA_VIA
where routes carry their own gateway.
Tested against a real kernel in both modes, with a link-local next hop
too, and in the lab against FRR and BIRD: the new `v6only` phase takes
the IPv4 addresses off the exchange LAN, runs one IPv6 session with each
router for both families, and pings IPv4 across.
Sessions between link-local addresses are not supported yet.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
New crate bgp-fib. It follows the routing table's best routes and keeps
the kernel's routing table the same, and learns the machine's interfaces
and addresses from the kernel, which is what says whether a next hop can
be reached.
- netlink: the rtnetlink messages used (routes, addresses, links, errors),
as bytes and back. No I/O; property tested and fuzzed.
- interfaces: what is directly reachable, and from which interface.
- plan: what to ask the kernel for, given the best routes and what the
kernel has. No I/O; tested against a model kernel.
- kernel (Linux only): the sockets and the task. Requests go in batches;
routes of ours found at startup are kept if still right and removed if
not; a change of interfaces has every route worked out again; a clean
stop removes our routes.
Only routes marked proto bgp with the configured table and metric are
ever touched. A best route is installed if its next hop is a neighbor;
next hops further away are not resolved through other routes yet, and
such prefixes are counted and shown instead.
Configured with `kernel { table metric }`; off by default. The daemon
needs CAP_NET_ADMIN and stops if the kernel refuses it. On shutdown it
closes sessions and then removes its routes.
/api/kernel and the status page show installed, unresolved and refused
counts, the last error and the interfaces; five bgp_kernel_* metrics.
Testing: scripts/kernel-tests.sh runs, in network namespaces of their
own and with only the capabilities the daemon needs, the installer
against `ip route`, the daemon with a peer, and two daemons that route
for each other with pings across over IPv4 and IPv6.
scripts/linux-vm.sh runs that, or anything else, in a Lima VM from
macOS. CI runs the kernel tests and fuzzes the netlink decoder.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
A peer's configured role now does three more things:
- Our OPEN carries the BGP Role capability with what we are to the peer.
A peer whose own says it is something that does not pair with that, or
that sends two different roles, is refused with OPEN Message Error /
Role Mismatch. A peer that says nothing is accepted unless require_role
is set. A role on a peer in our own AS is a configuration error.
- Routes from a provider, a peer or a route server are marked Only to
Customer on the way in if they are not already, and our routes are
marked on the way out to a customer, a peer or a route server client.
- A marked route from a customer or route server client, or from a peer
with someone else's mark, is a leak and is refused. No policy setting
turns that off.
The packet crate gains the Only to Customer attribute (malformed:
treat-as-withdraw), and the Role Mismatch subcode is corrected from 8 to
11.
The status page shows whether the peer confirmed its role.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Origin validation says who may originate a prefix and nothing about the
rest of the path: it does not catch a route leak, nor a hijack that keeps
the right origin at the end of a made-up path. ASPAs, in which a network
lists its providers, do.
bgp-rpki:
- aspa: the ASPAs and the upstream and downstream verification procedures
of draft-ietf-sidrops-aspa-verification-24, tested against the draft's
wording as written.
- rtr: protocol version 2 (draft-ietf-sidrops-8210bis-23) with the ASPA
PDU and the new error codes.
- client: asks for version 2 and falls back to whatever older version the
cache speaks; keeps ASPAs with the VRPs, applied whole or not at all;
publishes which customers' ASPAs changed; tells the cache why it is
being left (Error Report); does not ask one version's serial of another.
Server:
- A peer has a role (provider, customer, peer, route server, route server
client), which decides how its paths are verified. Without one they are
not.
- A route whose path is invalid is refused ("ASPA invalid") and held, like
one with an invalid origin; accept_aspa_invalid exempts a peer.
- When ASPAs change, routes in the table whose path has a changed customer
on it are verified again, and held routes are released when they pass
both checks.
- The revalidator finds a route's peer by index instead of searching a
list for every route.
The status page and API show each peer's role, each route's path validity,
the number of ASPAs and the RTR version in use; bgp_rpki_aspas is on
/metricz.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
With rpki { caches { ... } } in the configuration the server keeps the
validated ROA payloads of a validator and validates every route from a
peer outside its own AS (RFC 6811). An invalid route is refused, unless
its peer has accept_rpki_invalid. Valid and not-found routes are taken;
validity does not otherwise enter route selection.
Validity is not settled when a route arrives: the data changes every few
minutes. The routes follow, without the peer sending anything again.
- A route refused as invalid is held by its session, out of the table.
When the data changes the session looks at what it holds, and what is
no longer invalid goes into the table. A held route is the peer's to
withdraw or replace like any other.
- A route in the table that becomes invalid is found by a task that
looks through the table when the data changes, at the prefixes the
changed VRPs cover, and is taken out and held by its session.
- If the data expires because no cache confirms it, nothing is invalid
any more and everything held is taken.
- A session holds at most 200,000 routes; past that it asks the peer for
a route refresh when the data changes.
So that the table can be looked through without parsing attributes, an
attribute set's key now has the route's origin AS. Memory per route is
unchanged at 52 bytes on the real table.
Shown: /api/rpki and a section of the status page with the cache, its
state and the age of the data; each route's validity; each peer's count
of held routes. Refusals are recorded under "RPKI invalid". Metrics:
bgp_rpki_vrps and bgp_rpki_updates_total.
Also: Negotiated says whether the peer supports route refresh, and
docs/RFCs.md is brought up to date.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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>
- Implement passive-side BGP FSM (OpenSent → OpenConfirm → Established)
with hold timer, keepalive timer, and NOTIFICATION on expiry
- Add bgp-server crate: config validation, TCP listener accept loop
(BgpServerBuilder → BgpServer), connection dispatch
- Add bgp-rib crate: Adj-RIB-In actor owning route state with event
broadcast for streaming consumers and snapshot for introspection
- Wire Adj-RIB-In into FSM: announce/withdraw on UPDATE for both legacy
IPv4 NLRI fields and MP_REACH/MP_UNREACH path attributes
- Add bgp-integration-tests crate with 15 end-to-end tests covering
session establishment, timers, UPDATE handling, and RIB introspection
- Fix require_empty! macro bug in open.rs (checked wrong buffer)
- Fix FourByteAsn capability parser returning consumed buffer as remainder
- Fix tracing subscriber not being installed in TracingArgs::install
- Expand docs/RFCs.md with full implementation status across 15 RFCs
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
