A peer can now send several routes for one prefix, told apart by a path
identifier, and each is a route of its own in the table.
Wire:
- The ADD-PATH capability lists several address families. It was read as
exactly one, so the OPEN of a router offering it for IPv4 and IPv6 was
malformed and the session never came up.
- Prefixes in UPDATEs are `Nlri`: a prefix and a path identifier. The
identifier is on the wire, in the body and in MP_REACH/MP_UNREACH, for
the families the session uses ADD-PATH for in that direction. Sending
and receiving are settled separately, so a session has one codec context
for each.
Negotiation:
- `add_path` on a peer in the configuration: off (the default), receive,
send or both, offered for every family offered to the peer.
- In use for a family and a direction when one side offered to send and
the other to receive. Shown on /statusz and in /api/peers.
Table:
- A route is known by its peer and path identifier together. Identifiers
are stored only in rows that have a non-zero one, so routes of peers
that send one route each cost nothing more.
- Equal routes from one peer are chosen between by the lower identifier.
- /api/routes/received gives each route's path_id.
Journal:
- A second journal in each shard records every change to any route, for
followers that want all the routes of a prefix and not only the best:
RibTable::reader_of_all_routes and Event::Routes. This is what sending
several routes to a peer will read. It costs nothing while nobody
follows it.
Sending: prefixes go out with a path identifier where that was agreed, but
there is still one route for each prefix to send: only originated routes
are announced.
Tested with the table and journal model tests extended to path identifiers
and to followers of all routes, the codec property tests and fuzz targets
extended to ADD-PATH sessions, and end to end in both directions and for
the case where only one side offers it.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
The server now keeps what it learns in table::RibTable. The Adj-RIB-In
actor is gone, and with it the queue every UPDATE from every session went
through.
- A session takes a number in the table when it is established and writes
its UPDATEs into the table itself. Its routes are removed when it ends,
on a blocking thread since that looks at every prefix; a session torn
down without cleaning up still has them removed.
- For every prefix the best route is chosen (RFC 4271 §9.1.2.2) as routes
come and go. Nothing acts on the choice yet beyond showing it.
- The UPDATE decoder hands over the bytes of the attributes it kept, so the
table finds the attribute set from them without writing the attributes
out again. On a session with two-octet AS numbers the bytes are not in
the table's form, and the parsed attributes are used.
- /api/routes/received marks the best route of each prefix and returns at
most `limit` routes (default 1000): the table can hold hundreds of
millions. /api/status has the totals, and the status page says how many
it is showing. The time a route was received is no longer kept or shown.
- The event stream reports changes of best route (best_changed,
best_withdrawn) in place of every route received. Each client follows
the table's journal with a reader of its own, from the moment it
connects: table::RibTable::reader_from_now.
- Metrics: bgp_rib_routes, bgp_rib_prefixes, bgp_rib_attribute_sets and
bgp_rib_journal_entries replace bgp_adj_rib_in_routes.
- A line is no longer logged at INFO for every UPDATE sent or received; a
full table is a million of them. They are at DEBUG.
- A table with no room for another peer ends the session with Cease / Out
of Resources.
Four peers sending a synthetic full table each over TCP, 4.9 million
routes: 0.80 s, against 4.76 s before. One peer: 0.45 s against 0.69 s.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
The RIB handles swallowed every failure of their actor: an UPDATE applied
to a stopped Adj-RIB-In vanished, and a snapshot of it came back empty.
Sessions stayed up, peers' routes went nowhere, and the status page showed
a healthy router with no routes. An actor stops only by panicking, so this
is the state the server would be in after a bug.
- Every operation on AdjRibIn and LocalRib returns Result<_, RibStopped>.
LocalRibError is replaced by it.
- The server waits on both actors, the advertiser and the dialers. If one
stops it sends every peer Cease / Administrative Shutdown and returns an
error, so the process exits and can be restarted. Before, the tasks'
handles were held and never looked at.
- A session that cannot store an UPDATE ends with the same Cease.
- The HTTP API answers 503 with the reason for anything that needs a table
it cannot read, including /metricz: a scrape that fails is noticed, last
known sizes are not.
Also:
- The routes of a session are now removed even if its task is torn down
without running its cleanup (a panic), instead of staying in the table
as routes of a peer that is gone.
- Table sizes for the status page and metrics are asked for as a count
instead of copying the whole table to take its length.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
AFI and SAFI were closed enums, so a family without a variant could not be
represented at all, and the set of negotiated families was a struct with
one bool per family. Supporting another family meant touching both.
- `Afi`, `Safi` and `AfiSafi` in bgp-primitives are newtypes over the wire
numbers, with constants and names for the common families. Capabilities
and MP_REACH/MP_UNREACH use them, so any family a peer names is read as
what it is. The special case that turned a capability for an unlisted
family into an unknown capability is gone.
- `FamilySet` is a set of `AfiSafi`. What we can exchange routes for is the
explicit `family::SUPPORTED` list; only those are offered in our OPEN.
- `AddressFamilyId` stays as the IP version of a prefix.
- NLRI is still a list of IP prefixes. MP_REACH/MP_UNREACH for a family
whose NLRI is something else (labelled, VPN, EVPN, ...) is refused
rather than misread as prefixes, which is what happened before for the
SAFIs the old enum listed.
Bug found on the way: the reserved octet in MP_REACH_NLRI was skipped only
for IPv6, so an IPv4 MP_REACH_NLRI was parsed with an extra 0.0.0.0/0
route that the peer never sent.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
The OPEN used to offer IPv4 and IPv6 unicast unconditionally, and what the
peer offered was ignored apart from its four-octet AS number.
Address families (RFC 4760):
- A peer's `address_families` in the configuration says which to offer it;
all of them by default.
- A session carries the families both OPENs offered. A peer that sends no
Multiprotocol capability is a plain RFC 4271 speaker: IPv4 unicast.
- Routes of a family that was not negotiated are not sent, and are ignored
when received; the rest of the UPDATE is applied and the session stays up.
- A session with no family in common is refused with Unsupported
Capability, naming the capabilities we needed (RFC 5492).
- The negotiated families are shown on /statusz and in /api/peers.
Bugs found on the way:
- A capability naming an address family we have no constant for (EVPN,
VPNv4, ...) failed the whole OPEN, so such a peer could never establish.
It is now kept as an unknown capability and ignored.
- An UPDATE could not be encoded for a peer without four-octet AS support,
which ended the session on the first route. AS_PATH is now written two
octets wide with AS_TRANS where needed, and AS4_PATH carries the real
numbers (RFC 6793).
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Default settings. No change in behaviour; the tree was last formatted
before the lecture work and had drifted to a mix of line widths.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Routes were announced and withdrawn through an HTTP form, each tagged with a
free-text owner and checked against an allow-list and a per-owner limit.
That was the lab's interface, not a router's.
Routes now come from 'originate' entries in the configuration file and are
in the local RIB before any session starts. The local RIB holds one route
per prefix with no notion of owners or policy. local_route_policy is gone
from the configuration.
The HTTP API keeps its GET endpoints (status, config, peers, originated and
received routes, events, metrics). The announce, withdraw, wire-bytes and
well-known-community endpoints are removed, and the status page loses the
announce form, the community presets and the byte decoder. Community text
parsing moves from the web crate to bgp-packet so the configuration can use
it.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Preparing to run ferrix next to BIRD on the production router.
- build: the config proto is now parsed in pure Rust, so building needs no
`protoc` binary. It previously worked only where one happened to be
installed; the Dockerfile in this repo could not have built.
- peers gain `local_address`, the source IP for connections we open (and
therefore the next hop we advertise). When both speakers share a host
the OS would otherwise pick an arbitrary local address and the peer,
which identifies us by address, would refuse the session. Address-family
mismatches are rejected at config load; an address the host lacks shows
up as the peer's backoff reason.
- docs/lab/prod/on-router: static musl cross-build instructions, config,
hardened systemd unit (unprivileged, SIGTERM gives BIRD a Cease),
loopback addresses for networkd, the BIRD stanza for a same-host
multihop session, and reverse-proxy examples with TLS and a password,
since the API has no authentication.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
When both ends dial each other, exactly one TCP connection must survive
and both ends must pick the same one. Previously ferrix relied on the
other router to sort this out and could briefly hold two sessions.
- collision: a shared map keyed by the peer's BGP Identifier holds the one
connection currently preferred for that peer plus a kill signal. Each
connection calls admit() on receiving the peer's OPEN. The connection
initiated by the higher BGP Identifier wins; the loser gets Cease /
Connection Collision Resolution, whether it is the new connection or an
existing one in OpenConfirm running in another task.
- A collision with an Established session closes the new connection (RFC
default). The optional CollisionDetectEstablishedState is available as
collision_detect_established_state: a restarted peer's new connection
then replaces the stale session at once instead of being refused until
the hold timer expires. Enabled in the lab config.
- Two connections opened by the same side: the newer wins.
- OPEN validation rejects a peer using our own BGP Identifier or 0.0.0.0
with Bad BGP Identifier; collision resolution needs distinct identifiers.
- OpenConfirm no longer times out instantly when the negotiated hold time
is zero.
- Sessions record which side opened them; shown as "opened by" on the
status page and as `direction` in /api/peers. New counter
bgp_connection_collisions_total{closed}.
- Tests: unit tests for the rule (including that both ends agree), and
integration tests for simultaneous open in both identifier orders and
both arrival orders, Established default, restart replacement with route
flush, distinct identifiers, slot release, and Bad BGP Identifier.
Existing fan-out test now gives its two peers distinct identifiers.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
