add rate limiting relays doc

docs.json

@@ -96,7 +96,8 @@
             "pages": [
               "deployment/dedicated-infrastructure",
               "iroh-services/relays/public",
-              "iroh-services/relays/managed"
+              "iroh-services/relays/managed",
+              "relays/rate-limiting"
             ]
           },
           {

relays/rate-limiting.mdx

@@ -0,0 +1,105 @@
+---
+title: "Rate Limiting"
+description: "How relays throttle traffic per connection, and how to configure limits on a self-hosted relay"
+---
+
+## Why you're here
+
+If an iroh endpoint just logged something like this:
+
+```
+The relay is rate-limiting this endpoint; outbound relay traffic is being
+throttled. Send less data over the relay, or, if you operate this relay,
+raise Limits::client_rx.
+```
+
+it means the relay your endpoint is currently routed through has started
+throttling how fast it reads data from your connection. This is not an error.
+This just means that the connection stays open and traffic keeps moving, just
+slower than usual. 
+
+Two ways to fix it:
+
+- **Get a direct connection instead.** Relay rate limits only apply while traffic is relayed. A successful direct P2P path bypasses the relay entirely. If two endpoints keep falling back to the relay, see [diagnose a direct connection](/iroh-services/net-diagnostics/quickstart).
+- **Use a relay with a higher limit.** [Shared relays](/iroh-services/relays/shared) and [dedicated relays](/iroh-services/relays/managed) both allow more throughput than the public relays. If you run your own relay, raise or remove its limit — see [Self-hosted relays](#self-hosted-relays) below.
+
+This notice is sent at most once per connection, and only to endpoints at iroh
+version 1.0.4 or higher. Older  clients are throttled the same way but won't see
+the warning.
+
+## Public relays
+
+The [public relays](/iroh-services/relays/public) n0.computer runs are free,
+open to every iroh endpoint, and rate-limited to prevent abuse of shared
+infrastructure. 
+
+The exact thresholds aren't published, as they get tuned as needed. However, the
+mechanism is applied per connection. If you are using the N0 preset, you're
+sharing the relay's total capacity with every other tenant, so heavy traffic
+from other users can affect your experience even before your own connection hits
+its individual limit.
+
+Public infrastructure is meant for development and hobby use.
+
+## Shared and managed relays
+
+[Shared relays](/iroh-services/relays/shared) run on separate infrastructure
+from the public relays, with far fewer tenants per machine and higher
+per-connection limits.
+
+[Dedicated relays](/iroh-services/relays/managed) provisioned through Iroh
+Services are dedicated to your project — no other tenants, no rate limits at
+all.
+
+## How it works
+
+Rate limiting is a property of a single relay *connection*, not a global switch.
+
+Each client connection gets its own token-bucket limiter on the side of the
+relay that reads data sent by that client (`rx`, for "receive"):
+
+- **`bytes_per_second`** — the steady-state rate the relay will keep reading from that connection.
+- **`max_burst_bytes`** — how far a client can exceed that rate momentarily before the bucket runs dry.
+
+When a client's bucket empties, the relay stops reading from that connection's
+socket until it refills. Data isn't dropped — the client just experiences
+backpressure: writes to the relay stall until the bucket has room again. This is
+what triggers the one-time `RateLimited` status notice.
+
+Because the limiter is per-connection, one client hitting its limit doesn't affect any other client on the same relay.
+
+## Self-hosted relays
+
+If you run the `iroh-relay` binary (or embed the `iroh-relay` server crate)
+yourself, rate limiting is **off by default**. This means connections can send
+unlimited data. 
+
+With the `iroh-relay` binary, configure it in your TOML config file:
+
+```toml
+[limits.client.rx]
+bytes_per_second = 1_000_000
+max_burst_bytes = 2_000_000
+```
+
+`bytes_per_second` is required to enable the limiter; `max_burst_bytes` is
+optional and defaults to no burst allowance above the steady rate if omitted.
+
+If you're embedding the relay server as a library, the equivalent is
+`iroh_relay::server::Limits::client_rx`. This is the field the client-facing
+warning message refers to when it says "raise `Limits::client_rx`".
+
+<Note>
+`Limits` also has `accept_conn_limit` / `accept_conn_burst` fields for rate-limiting new incoming connections. As of this writing they're reserved but not yet enforced — setting them has no effect.
+</Note>
+
+Consider a per-connection limit even on a single-tenant dedicated relay: it protects your egress bandwidth and CPU from a single misbehaving client or a bug in your own application, not just from other tenants.
+
+
+## See also
+
+- [Public Relays](/iroh-services/relays/public)
+- [Shared Relays](/iroh-services/relays/shared)
+- [Managed Relays](/iroh-services/relays/managed)
+- [Dedicated Infrastructure](/deployment/dedicated-infrastructure)
+- [Relay source (`iroh-relay`)](https://github.com/n0-computer/iroh/tree/main/iroh-relay)