Rayhaan JaufeerallyandClaude Fable 5.1
630c175918
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>
66 lines
2.6 KiB
Markdown
66 lines
2.6 KiB
Markdown
# BGP
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This crate provides the `bgp` binary, which runs the Border Gateway Protocol
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daemon together with its read-only HTTP status interface.
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```
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cargo run -- path/to/config.textpb
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```
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The configuration format is defined in `crates/server/proto/config.proto`;
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`testdata/server.textpb` is a worked example. The daemon is configured
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entirely through that file: peers, and the routes it originates
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(`originate { prefix: ... }`). There is no way to change either at runtime.
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When `http_endpoint` is set the binary also serves:
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| Path | Purpose |
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|---|---|
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| `GET /statusz` | Status page: configuration, peers and session state, originated and received routes, live event log |
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| `GET /api/status` | Router ID, ASN, uptime and table sizes |
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| `GET /api/config` | The configuration file as read at startup |
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| `GET /api/peers` | Configured peers and established sessions |
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| `GET /api/routes/local` | Originated routes |
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| `GET /api/routes/received` | Adj-RIB-In contents |
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| `GET /api/events` | Server-sent events for session and route changes |
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| `GET /metricz` | Prometheus metrics |
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Everything under it is read-only and unauthenticated. Bind it to loopback or
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put it behind a reverse proxy.
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## What it does today
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It establishes sessions (both dialling configured peers and accepting
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connections, with RFC 4271 collision detection), announces its originated
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routes to every peer with itself as next hop, and records what peers send in
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an Adj-RIB-In. It does not select best paths, re-advertise received routes or
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program a forwarding table, and it has no import or export policy.
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## Who may connect
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Connections are taken only from the addresses of configured peers, and from
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each of those only a few at a time. Anything else is closed unread and
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counted in `bgp_connections_refused_total`. `accept_unconfigured_peers: true`
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lets any host open a session as any AS; it exists for tests on a closed
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network.
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## Trying it without a router
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`fake_peer` is a minimal BGP speaker that connects to the daemon, announces a
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prefix, prints every UPDATE it receives and, with `--echo`, re-announces each
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received prefix back with its own ASN prepended (dropping NO_EXPORT routes).
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That makes originated prefixes show up in the received table as if they had
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travelled through a neighbouring AS:
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```
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cargo run -- testdata/server.textpb
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cargo run -p bgp-integration-tests --example fake_peer -- \
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--server 127.0.0.1:179 --asn 65001 --announce 203.0.113.0/24 --echo
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```
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Please refer to the other implementation crates in this repository where most
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of the actual implementation lives.
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Warning: This is still very much a work in progress and is not yet ready for
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production use.
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