Against a production BIRD router, restarting ferrix was followed by
several refused connection attempts before the session came back.
- The daemon had no signal handling: Ctrl-C killed the process and the
peer only ever saw a dead TCP connection. On SIGINT or SIGTERM it now
sends Cease / Administrative Shutdown (RFC 4486) to every established
peer, waits up to two seconds for the sessions to close, and stops the
dialers from reconnecting meanwhile. A NOTIFICATION queued for a session
ends that session once sent.
- ROUTE-REFRESH was parsed and ignored. A peer sends it when its import
policy changes (e.g. after `birdc configure`), expecting our routes
again so the new policy can be applied. The session now reports the
request and the advertiser re-sends every local route to that peer. The
request also appears in the event stream and the status page log.
Tests: a refresh request in real wire format re-sends all routes and keeps
the session up; shutdown delivers the Cease to every peer and closes the
sessions. Verified with the real binary: SIGINT, peer logs the Cease.
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>
Phase 5 of the teaching demo plus two fixes found while exercising the
dialer on the status page.
- Adj-RIB-In: routes learned from a peer are removed when its session ends
(RFC 4271 §8.2.2), emitting a Withdrawn event per prefix before the
session Down event. Previously stale routes from dead sessions stayed in
the received table.
- statusz: poll the peers table every 5 s so dial state (Connecting /
Backoff and its retry countdown) stays current; those changes carry no
event.
- docs/lab: docker-compose topology with ferrix (AS65000) and two FRR
routers. r2 accepts nothing directly from ferrix so student prefixes
only reach it via r1, then come back with AS path 65002 65001 65000. r1
applies community-driven policy: NO_EXPORT stops forwarding, 65001:100
prepends, BLACKHOLE drops. Dockerfile for the daemon.
- docs/lab/HANDOUT.md: student exercises walking through announcement,
reading the bytes, prepending, NO_EXPORT, action communities,
blackholing and withdrawal.
The container files have not been executed (no runtime available here);
docs/lab/README.md lists what is most likely to need adjusting.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Phase 1 of the BGP teaching demo: the daemon can now originate routes and
advertise them to every established peer.
- rib: add LocalRib actor holding locally originated routes with owner,
origin, AS-path prepend, MED, standard and large communities. Enforces a
LocalRibPolicy (prefix allowlist, per-owner limit, owner match on
replace/withdraw) and emits LocalRibEvents.
- server: add SessionRegistry with per-session outbound queues; sessions
register on Established and deregister via a drop guard. Emits
SessionEvent::{Up,Down}.
- server: advertiser task fans LocalRib changes out to all sessions and
replays the table to new sessions. UPDATE builders handle IPv4 (legacy
NLRI) and IPv6 (MP_REACH/MP_UNREACH).
- fsm: merge the timer and timer-less established loops into one select!
with an outbound branch; reset the hold timer on any received message
per RFC 4271 §8.2.2 (previously only on KEEPALIVE).
- config: new local_route_policy proto message.
- packet: fix Communitites typo, expose CommunitiesPathAttribute inner vec.
- primitives: IpPrefix::contains.
- integration tests: announce/withdraw/replay/fan-out/policy coverage.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
