d7d7d39bb9a315df39bdf14b438e4414322259c1
15
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Rayhaan JaufeerallyandClaude Fable 5.1
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d7d7d39bb9 |
metrics: export each session's TCP connection figures
The kernel's view of a session's TCP connection, which the status page shows on request since the last change, could not be looked at after the fact: a feed that crawled overnight left no record of whether the peer's window or our own side held it up. This change samples it at every scrape of `/metricz`: for each established session, one `NETLINK_SOCK_DIAG` round trip, and twenty gauges labelled by peer, `bgp_peer_tcp_*`: smoothed, least and variance of the round-trip time; the congestion window and segment size; the peer's receive window and ours; the send queue, the part of it not yet sent, the receive queue and the segments in flight; retransmitted and lost segments; the busy time and the time held up by the peer's window and by our send buffer, cumulative, so that their rates give the share of time a session is held up; octets sent and received; and the delivery and pacing rates. A session the kernel has no connection for loses its series, as does one that ends. `SessionHandle::metric_label` is the one place a peer's metric label is made (its name, or its address), used by the advertiser's gauge and here. Documentation: the metrics reference lists them; the monitoring guide gives the query for the share of time a session is held up by the neighbor's receive window, which is the question the overnight feed raised. Testing: a daemon in the Linux VM with one session shows the series and drops them when the session ends; the lab's basics phase checks the scrape for the FRR session's round-trip time; the workspace tests pass. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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99a47da2af |
status: a session's TCP connection as the kernel sees it; a route in full
When a session advertised a full table to a route collector at two thousand routes a second, nothing on the status page said whether the daemon or the peer set that pace. The answer is in the kernel: the peer's receive window, the queues, and how long the connection was held up by the window or by the send buffer, which `ss -ti` shows. This change asks the kernel the same way `ss` does, over the socket diagnostics netlink family (`NETLINK_SOCK_DIAG`, `SOCK_DIAG_BY_FAMILY` with the connection's addresses and ports), and reads `tcp_info` and the congestion control name from the answer. No external program is run and no unsafe code is needed: the request and the answer are byte layouts of the kernel's ABI, read field by field, with fields an older kernel does not send left at zero. A socket on a link-local address is found by its interface, which the request names. * `bgp_fib::sockdiag`: the request, the parser, `TcpConnection`, and `tcp_connection(local, peer)`; `Ok(None)` where there is no such connection or the system is not Linux. * `GET /api/tcp?peer=ADDRESS` in the HTTP API: the connection of the session with that peer, with times in milliseconds, the two windows named by what they allow, and the held-up times also as shares of the busy time. * The status page: a "tcp" link on each established session, which expands a row below it with the figures, re-asked on every refresh while open. The group rows' span is corrected for the "sent" column. Also on the status page: the attributes of a received route that have no column of their own were badges with their value in a tooltip, which is hard to read. Clicking the attrs cell now expands a row under the route with every attribute by its name (ORIGIN, AS_PATH, NEXT_HOP, MED, LOCAL_PREF, COMMUNITIES, LARGE_COMMUNITIES, AGGREGATOR and the rest), the path identifier, the selection rank and the RPKI and ASPA states; the badges stay. Both expansions use the terms of `ss` and the RFCs rather than sentences. Documentation: the endpoint in the HTTP API reference, and the link and the expansion in the monitoring guide. Testing: unit tests of the request and of the parser on a reply built field by field, and of a "no such socket" and a refused answer; a Linux-only test that asks the kernel about a loopback connection of the test's own and about one that does not exist; the lab's basics phase checks the endpoint for the FRR session; the page was checked by hand against the daemon in the Linux VM. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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ec5c9be454 |
export: advertise every route for a prefix with ADD-PATH (all_paths)
Before this change, a session on which ADD-PATH (RFC 7911) was
negotiated in the sending direction was sent path identifiers, but only
the best route for each prefix. A route collector such as bgp.tools
wants every route a router has accepted, from every neighbor, and from
one session: without this the collector saw one path per prefix, nearly
always the same neighbor's.
This change adds `all_paths` to the export policy. On a session with it,
and ADD-PATH send negotiated for a family, every accepted route for a
prefix of that family is advertised, each with a path identifier of its
own; for a family without ADD-PATH send the best route goes as before.
`all_paths` needs `learned_routes` (a configuration error otherwise) and
the peer's `add_path` to offer sending. The export policy, the role
rules, the well-known communities and the export limits apply to every
route alike, and the export limits count every route.
Implementation, in the advertiser:
* An exporter with `all_paths` follows the table's journal of all routes
(`RibTable::reader_of_all_routes`, until now unused) instead of the
best-route journal, and is given all the routes of a prefix whenever
one of them changes (`News::Routes`).
* What the peer holds is `Announced`: the set of prefixes for a
best-route session, as before; or for an all-paths session, for each
prefix the routes announced, keyed by the peer they came from and that
peer's own identifier, with the identifier they went out with and the
form they went out in. A route keeps its identifier for as long as it
is announced, goes out again only if it changed, and is withdrawn by
its identifier; a new route gets the lowest identifier not in use for
the prefix, from 1.
* Verdicts carry either kind (`Verdict::Best`, `Verdict::All`), and a
reset of the table puts what was announced in doubt until heard of
again, as before, with the same identifiers kept across the reset.
* The record for an all-paths session is about 50 bytes a route, some
tens of megabytes for a full table from several neighbors; the
best-route bookkeeping is unchanged in size.
Also, so that a collector session can be watched: the number of routes
advertised to each peer and not withdrawn since, every route counted
where several are sent for a prefix. The exporter keeps it in the
session's counters after every change; it is `advertised_routes` in
`/api/peers`, the "sent" column of the status page's neighbor table,
and the gauge `bgp_peer_advertised_routes{peer}`.
Documentation: a "Feeding a Route Collector" section in the guide to
passing routes on, with the configuration for a collector; `all_paths`
in the configuration reference; the ADD-PATH sections of the neighbor
guide and the standards reference; the limitation that was removed;
the new field, column and metric in the HTTP API, monitoring and
metrics references.
Testing: an integration test with two feeders and a collector that
negotiated ADD-PATH receive, which checks the two routes with their
identifiers, the withdrawal of one by its identifier, a changed route
keeping its identifier and a new route taking the free one; a
configuration test for `all_paths` without `learned_routes`; a new
`collector` phase of the interoperability lab in which FRR, as a route
collector, is told both of BIRD's routes for a prefix from BIRD's two
sessions and holds them apart, and loses one when its session is
disabled, with the advertised count checked at each step. The workspace tests, the kernel tests and every lab phase pass.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Rayhaan JaufeerallyandClaude Opus 5.5
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9cfd3f67f0 |
Export limits, and a role for every peer where routes are passed on
What other networks were told of rested on one thing: the Only to Customer mark that routes from providers, peers and route servers get as they come in. A route without it, from a session without a role or by a mistake anywhere along the way, went to every peer, from every router of ours, and nothing of ours stood in the way. export_limits are a second check, independent of the roles, the marks and the export policy. For peers above or beside us (PROVIDER, PEER, ROUTE_SERVER, and any in another AS without a role): - prefixes: only routes for these go out, learned or our own. With our and our customers' space listed, a leak of anyone else's routes goes nowhere above us. - max_prefixes: if more routes were to go out than this, none of them does. The session ends with a Cease / Administrative Shutdown whose Shutdown Communication says why (RFC 9003), and the peer is held down for its import.hold_down_seconds, so that it is told nothing rather than too much. The whole table is counted before any of it is sent. They are set at the top and hold for every such peer that has none of its own; unlike `export`, a peer's own export policy does not drop them. A peer's own export_limits take their place, and an empty one lifts them. Customers, route server clients and our own routers are not limited. A configuration in which learned routes are passed on and a peer in another AS has no role is now refused, as is accept_unconfigured_peers with learned routes: without a role, a peer's routes go to everyone and it is told of everything. This used to be a warning. At startup, a warning for each peer the limits apply to that has none, and for each originated route the limits leave out. A metric, bgp_export_limit_exceeded_total, counts the sessions ended for it. The interop lab has a phase in which a customer leaks: a route outside its space never reaches BIRD, and when more were to go than the limit, BIRD's session ends and its log has our reason. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> |
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Rayhaan JaufeerallyandClaude Opus 5.5
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72444c2706 |
Control communities: session groups, prepends, and only ours to give
Control communities could say which peers a route goes to, by AS. Now
they can also name sessions by group, and ask for prepends:
L:11:P .. L:13:P our AS once to three times more towards AS P
(P 0: towards every peer in another AS)
L:20:G / L:21:G not to / only to the sessions of group G
L:31:G .. L:33:G our AS once to three times more towards group G
A group is a number given to sessions in the configuration (`groups` of
a peer): those at one exchange, or those over one link. The same network
at two exchanges is one AS but two sessions, which is what steering
inbound traffic between exchanges needs. Of several prepends that apply
the most counts, on top of the session's own as_path_prepend. Functions
2 to 9, as the documentation already promised, and 100 and up stay
informational; 10 to 99 are kept for actions to come.
They are acted on where a route leaves our AS, and taken off there; our
informational communities are not. To a peer in our own AS a route goes
with them, unchanged, so that a mark put on at one router is acted on at
another. Before, they were acted on and taken off on internal sessions
too, so a route marked "to nobody" did not even reach our own routers.
And they are ours to give: the communities of our own AS (L:n, L:n:m,
and 0:n where control communities are on) are taken off every route
from a peer in another AS as it comes in, before import marks are put
on. A peer at an exchange could otherwise decide where its routes go
from us, and set our informational marks. A customer that is to steer
its own routes is given import.accept_control_communities. An UPDATE
without any of ours is still taken as it came, without being written
out again.
This changes what a customer that set control communities gets: it now
needs accept_control_communities. The transit example and the interop
lab say so; the lab also has FRR, as a customer, ask for a prepend
towards BIRD's group, and BIRD, as a provider, have its "not to" taken
off.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Rayhaan JaufeerallyandClaude Opus 5.5
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3609451bdc |
Ignore our own prefixes from our own routers, and say why a route for a network of this machine is held
Two routers of an AS that both originate a prefix (anycast) each announce it to the other over their internal session. Each took the other's route, could not install it in the kernel, since the prefix is on one of its own interfaces, and so held it, counted as rejected with "next hop unreachable": a permanent rejection on a healthy session, for a next hop that was in fact fine. A route from a peer in our own AS for a prefix this router originates is now ignored: not taken, not held, not counted. Only that prefix itself; what is inside it is judged as usual. From other networks such routes are refused as our own prefixes, as before. A route that is held because its prefix is a network of this machine, or inside one (an exchange's LAN prefix, say), is now counted as "prefix is a network of this router", apart from routes whose next hop cannot be reached. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> |
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Rayhaan JaufeerallyandClaude Opus 5.5
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65f136048e |
Graceful restart (RFC 4724, RFC 8538)
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> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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1e2e8f2d86 |
Pass learned routes on to peers, with marks and control communities
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>
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Rayhaan JaufeerallyandClaude Fable 5.1
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9367c38907 |
Remove policy scripts
Rhai made a decision about a route cost one to three microseconds, some two hundred times what the same costs in Rust. That was bearable where a function is asked once for an UPDATE, and is not where every route is weighed against every peer, as it is when routes are passed on. What is wanted of a policy (mark routes by where they came from, mark what is announced, let communities say who is told what) needs no language; it is to be configuration, done natively. Kept from that work: route selection goes by a LOCAL_PREF that policy set on a route from an external peer, and the lab's configuration can be added to by a phase. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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cbf0df1eef |
Policy scripts: the operator's own rules for routes, in Rhai
A new crate, bgp-policy, runs functions of a script on routes: on their
way in, after the general checks of a peer's import and before the
checks that can change (RPKI, next hop reachability); and on their way
out to a peer. A function is given the route and the peer, may refuse
the route, and may change its communities, large communities,
LOCAL_PREF and MED, and on the way out prepend our AS:
fn from_peer(route, peer) {
if route.has_community("65535:666") { return false; }
route.add_community(LEARNED_FROM[peer.role]);
route.local_pref = PREFERENCE[peer.role];
true
}
Configuration: policy { path | source, import_function, export_function }
and, for a peer, import { function } and export { function }. The script
is compiled at startup; `bgp --check` reads it and says which function
is whose. A function that fails on a route has refused it. Scripts have
no files, network or clock, and are stopped after 200,000 steps.
Route selection now goes by a LOCAL_PREF on a route from an external
peer: the decoder never lets a peer's own through, so one that is there
was set by policy.
What it costs was measured before it was built on (benches/policy.rs):
a call that tests a few communities and changes two takes 1 to 3
microseconds, some two hundred times what Rust would. So a function is
asked once for the routes of an UPDATE, which share their attributes,
unless it asks for the prefix. One peer sending 1.23 M routes over a
session: 0.37 s without a function, 0.80 s with one that marks and
ranks every route, 3.4 s if it also looks at the prefix.
Export applies to what is announced, which today is what the daemon
originates; learned routes are not passed on yet.
Tested by unit tests of the crate, sessions end to end, a fuzz target on
the example script (testdata/policy.rhai), and a lab phase in which a
script changes which of FRR's and BIRD's route is chosen and what each
of them is told.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Rayhaan JaufeerallyandClaude Fable 5.1
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f1d80c66df |
Do not choose a route whose next hop cannot be reached (RFC 4271 §9.1.2.1)
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> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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9ca86ede2f |
Harden import, the kernel task and the RTR client after review
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> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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fd2248feb5 |
Peer at link-local addresses: fe80::1%eth0
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> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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92e013ca01 |
Carry IPv4 routes over IPv6 sessions with IPv6 next hops (RFC 8950)
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> |
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Rayhaan JaufeerallyandClaude Fable 5.1
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321af51e4b |
Add an interoperability lab with FRR, BIRD and Routinator
scripts/interop/lab.sh runs the daemon against FRR, BIRD and Routinator, each in a network namespace on one exchange LAN, and checks what every side ends up with: sessions and routes over IPv4 and IPv6 with their attributes, four-octet AS numbers, ADD-PATH, RFC 9234 roles and Only to Customer, RTR version 2 and invalid routes, route refresh, session resets, killed peers, a cut wire, the daemon stopped and killed, a table of a million routes and a restart under it, role mismatch and the prefix limit. All of it passes against FRR 10.5.1, BIRD 2.18 and Routinator 0.15.2. scripts/interop/real-rpki.sh checks the RTR client against a Routinator with the real RPKI: 713,258 IPv4 and 187,479 IPv6 VRPs and 3,379 ASPAs, the same numbers on both sides. What the lab found, fixed here: - A daemon restarted with its routes in the kernel removed them all at once, its table being empty until the peers had sent theirs again, and then put them back: no forwarding meanwhile. Routes of an earlier run are now kept for `stale_seconds` (120 by default) and only those nobody announced again are removed. A restart under a million routes takes 1.1 s to be in step, with nothing removed. - FRR ends a session it loses to a collision with a state machine error without a subcode, which was shown as "error code 5 subcode 0". CI gets a job that runs the lab. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> |