> ## Documentation Index
> Fetch the complete documentation index at: https://dragonwingdocs.qualcomm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# QRTR Overview

> Connectionless message routing between nodes, ports, and services.

QRTR is a connectionless message-routing service that lets software components on the same processor or different processors exchange messages. It separates the addressing and service discovery from the physical transport, so a service can communicate without depending on one specific link.

## QRTR architecture

```mermaid theme={null}
flowchart LR
    App[Client or service] --> Port[Local port]
    Port --> Core[Router core]
    Core --> XPRT[Transport interface]
    XPRT --> Link[Physical transport]
    Link --> Peer[Peer router]
    Peer --> Remote[Remote port]
```

The router core handles message routing, service discovery, and flow control. The transport interface abstracts away the details of the physical link (Shared Memory / RPM or another mechanism) so the router works the same way regardless of how data actually moves.

## How clients and services communicate

* **Endpoints** – Each client or service is identified by a node ID (which processor it runs on) and a port ID (which port on that processor). A service can also register a service name so clients can find it without knowing the exact port.
* **Service discovery** – When a client needs to talk to a service, it looks up the service name. The router advertises which node and port the service is on, and the client can then send messages there.
* **Connectionless delivery** – The router does not maintain a connection. Each message is independent, and the client must handle the fact that services can come and go, or move to a different port.
* **Message flow** – A client sends a message to a destination port. The router consults its routing tables, forwards the message through the network, and delivers it to the destination. The destination can send a response or an event back.

## Next steps

* [Architecture](architecture) — Understand the router layers, routing tables, and network topology
* [Addressing](addressing) — Learn how endpoints and services are identified
* [APIs](apis) — Use the kernel and socket interfaces to create ports and send messages
* [Operations](operations) — Manage power, synchronization, flow control, and diagnostics