A peer that restarts keeps its routes with us, and we keep ours with our
peers while we restart, so that a restart withdraws nothing across the
network and the machine goes on forwarding. On by default for every
peer; `graceful_restart` sets the restart time we give, caps how long a
peer's routes are kept, or turns it off.
When a peer restarts: its routes are marked stale in the routing table,
and chosen as before, for at most its restart time. When it is back, what
it sends again is fresh, and the stale routes of a family go at its
End-of-RIB marker, or after the cap; at once for a family whose
forwarding it did not keep. Only a connection that failed counts as a
restart, and, with RFC 8538 agreed, an expired hold timer or a
NOTIFICATION other than a Hard Reset. The stale mark is a bit of the
route's word that selection never looks at.
When we restart: SIGUSR1 leaves the kernel's routes where they are,
closes the sessions without a word where graceful restart is agreed, and
exits with status 75, on which the systemd unit starts us again. The next
start finds the routes in the kernel, says so in its OPENs (R, and F where
forwarding was kept), and has them go once every peer has sent its
End-of-RIB. Our own End-of-RIB markers for learned routes wait for that
too. SIGTERM still stops for good, now with a Hard Reset where RFC 8538 is
agreed, as are errors of ours.
The status page and API show what was agreed with each peer, the routes
kept while a peer restarts, and which routes are stale. Tested against
FRR and BIRD in a new phase of the interoperability lab, and with routes
kept in a real kernel over a restart.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The "refused" column counted rejected announcements since the start, not
routes, which made two peers that send the same routes look different
when one of them re-sends more often. It is now "rejected announcements",
with the held routes, the number that compares, beside it as "held now".
The page says "rejected" throughout, as the documentation and metrics do.
Rows are highlighted under the pointer, and pointing at an AS number
shows its holder's name, which the browser asks RIPEstat for. The daemon
looks nothing up; the monitoring page says what the browser sends where.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A route with the BLACKHOLE community (RFC 7999) asks for the traffic to
its prefix to be dropped. Exchange route servers pass these on as host
routes with the exchange's blackhole address as next hop, and they were
rejected as "prefix too specific", which hid what they are.
Routes from EBGP neighbors with BLACKHOLE are now rejected as "blackhole
request", whatever their length. One short enough to pass would have
been taken as an ordinary route, sending the traffic to the blackhole
next hop: the request honoured without anyone having chosen to. Acting
on blackhole requests is not supported; the import policy page and the
standards list say so.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A rejected route was recorded with its prefix, reason and AS path, which
is not enough to tell why a neighbor sent it: whether a /32 is a
blackhole request, which communities a leaked route carries, which
network marked it Only to Customer.
Each recorded rejection now keeps the attributes of the UPDATE it came
in, without the NLRI of MP_REACH_NLRI and MP_UNREACH_NLRI, and its next
hop. The attributes are copied once per UPDATE, only when a route of it
is rejected, and shared by its rejected routes. A route rejected later,
when the RPKI data changes, has the attributes it was stored with.
/api/routes/rejected gives them as `summary` and `attributes`, as for
received routes, and the status page shows them under "show" in each
row of the refused routes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
scripts/build-static.sh builds the daemon for x86_64 Linux against
musl, as one executable without dependencies to copy to a router. It
finds a musl C compiler for jemalloc (musl-cross on macOS, musl-gcc on
Linux), and uses its ar and ranlib too: with the host's, a build from
macOS gets an empty libjemalloc.a and fails to link. It prints the
revision and the SHA-256 of the result.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A full table from several neighbors means millions of small, long-lived
allocations that are replaced as routes change. jemalloc keeps the
resident size of such a workload closer to what is in use than the
system allocator does, glibc's in particular, and does not depend on
the C library the binary is linked with. Not on MSVC, which jemalloc
does not support.
Building now needs a C compiler and make; the installation page says
so.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The blue two-colour treatment is replaced by the photograph's own
colours, slightly darkened, under a neutral shade that keeps the text
legible.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The documentation moves from READMEs into a site in docs/: getting
started, a user guide, operations, a reference, and development pages,
written in the style of network vendors' documentation (docs/STYLE.md).
bin/bgp/README.md and docs/RFCs.md are folded into it.
- A theme of its own in the International Typographic Style, in blues,
with self-hosted Inter and JetBrains Mono, search over Zola's index,
dark mode, and no resources loaded from other hosts.
- Example configurations in docs/examples/, shown on the pages and
checked with `bgp --check` in CI.
- A test that fails when a field of config.proto is missing from the
configuration reference.
- A CI job that builds the site; Zola fails on broken links and anchors.
- A hardened systemd unit, tried under systemd with kernel routes on.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
What was to be scripted is configuration, done natively:
- import { add_communities, add_large_communities, remove_communities,
local_pref }: every route taken from a peer is marked (where it was
learned, say), with nobody else's word for our marks taken, and given
its preference, which selection goes by.
- export { add_communities, add_large_communities, remove_communities,
as_path_prepend, learned_routes }, for a peer or for all that have none
of their own.
- control_communities: the communities by which routes say which peers
they are passed on to, as exchanges' route servers have them (0:P, L:P,
0:L, and the large forms L:0:P, L:1:P, L:0:0), taken off as the route
goes on.
And what the last of these is for: with export.learned_routes a peer is
told the best route of every prefix the others announced. The rules are
BGP's and cannot be turned off: not back where it came from, not to a
peer whose AS is on the path, not between two internal peers, not past
NO_EXPORT or NO_ADVERTISE; our AS on the path and ourselves as next hop
to another network, LOCAL_PREF to our own; to a route server's client
the path, MED and next hop as they came (RFC 7947). Which routes go where
follows from the roles of RFC 9234: a route that came down or across goes
on down only, so that with roles on every peer this makes us transit for
our customers and nothing else. A peer without a role is told everything,
and the daemon says so at startup.
Each session follows the table's best routes with a reader and keeps the
prefixes it has announced, so that it can withdraw them. Routes that go
out alike go in one UPDATE: changes are gathered for 50 ms first, and a
table that is given out anew is gathered whole (at most four sessions at
a time; it is tens of megabytes). For that to work the table's journal
had to give out together what was written together: every change now
carries a time on a table-wide clock, a reader's pass reads every shard
up to one time, no further than the changes that are complete in every
shard, and a resync takes its places in the journals as of one time.
One peer sending 1.23 M routes over a session, another told of them:
in our table after 0.47 s, all heard after 2.1 s, four routes an UPDATE.
The lab has a phase, transit: FRR as our customer and BIRD as our
provider, routes each way with the right paths and marks, one kept back
by a community, and pings between their networks through us.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Where routes go into the kernel, a route the kernel could not be given
is no longer taken into the table: its next hop is no neighbor on any
interface, or its prefix is a network the machine is itself on. Such a
route used to be able to win selection and then leave its prefix without
a route in the kernel, though another peer had one that worked.
It is held aside the way an RPKI-invalid route is, and by the same
means: judged on arrival against the interfaces as the kernel last
described them, looked for in the table when they change, and taken
from what is held when its next hop can be reached. The fib publishes
the interfaces for this; the next hop is resolved once for an UPDATE
and not for each of its routes.
The lab has a phase, nexthops: FRR's better route with a next hop that
is nowhere is held and BIRD's is installed, and they change places as
an address comes and goes.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
What the code-health review found, and what a fuzz target written for it
found in its first seconds.
- A set of attributes with the same attribute twice is refused by the
routing table. Its readers (the selection key, the path, the next hop)
could each take a different one of the two. The decoder never lets one
through; the new fuzz target `attrs` found that the table would.
- bgp_peer_up{peer}, to alert on a peer going away, and bgp_build_info.
Every metric is there from the first scrape. Alerts for a peer down,
hijack attempts and kernel errors are in the README.
- `bgp --check config` validates a configuration without starting, and
`--version` says which build it is. CI runs the first on the example
configuration, which a test now also parses with its commented fields
put in; the example had to learn about the next hop check.
- Path attributes have a module of their own, packet::attributes,
re-exported from packet::message as before.
- policy::From, which shadowed the trait, is RouteSource. The server's
connection, dialer and fsm modules are private. Logging arguments live
in the binary; the server library no longer depends on clap.
- One is_unicast_link_local (the standard library's) instead of two of
our own; SelectionKey::origin(); one place where an Import is made.
- READMEs say what the daemon does today rather than what it did not do
a year ago. Documentation links are checked in CI. Unused dependencies
and bgp_web::serve are gone; the Docker build is --locked and does not
ship the fuzz corpus.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Three independent reviews (hijack resistance, reliability, code health)
of the whole tree. This is what they found that could let a bad route in
or take the daemon down.
Hijacks:
- A route had two paths on a two-octet session, AS_PATH and AS4_PATH,
read in two places by two rules. A peer could make the origin checked
on import differ from the one checked at revalidation, and get an
RPKI-invalid route into the table. AS4_PATH is now merged into AS_PATH
once, on receipt (RFC 6793 §4.2.3), and nothing else knows of it.
- The next hop is judged on import: it must be usable, agreed on
(RFC 8950), and by default the peer itself.
- Our own originated prefixes are not taken from other networks.
- A route for a network the machine is on is never put in the kernel.
- Paths with an AS_SET are refused (RFC 9774).
- A configured peer gets one session, not one per BGP Identifier.
- More IPv6 special-purpose prefixes are bogons.
Reliability:
- A batch of requests the kernel refused could overflow the netlink
socket and end the daemon. The socket has room now, a lost answer or a
silent kernel means asking what is there, and neither is fatal.
- Working the routes out again within the grace period after a restart
no longer drops the routes being kept.
- That work can no longer be put off for ever by interface changes.
- Peers whose sessions keep failing are slowed down.
- Unused attribute sets are swept when they pile up, not only each
minute.
- Log lines a peer can cause are said once in a while.
- An RTR answer is bounded in size and time; data cannot expire between
two refreshes.
- The shard of a key is taken from a stirred hash: neighbouring bits of
the hash proved alike for prefixes in a row. The test that showed it,
failing one run in sixteen, is deterministic now.
The lab has a phase, hijacks, in which FRR tries the first three.
route::apply is a struct with methods instead of nested closures, and
the kernel task's loop is shorter.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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>
