# Connection status management (/en/realtime-media/interactive-live-streaming/build/optimize-quality-and-connection/connection-status-management/web) > For AI agents: see the complete documentation index at [llms.txt](/llms.txt). In real-time audio and video implementations, the connection state between the app and Agora SDRTN® changes as the client joins or leaves the channel. The connection may also be interrupted due to network or authentication issues. This page describes the various channel connection states, reasons for state changes, and how to handle these changes to better manage your users and troubleshoot network faults. ## Understand the tech [#understand-the-tech-3] The following figure shows the various connection states and how the connection state changes between a user joining and leaving a channel: ![Connection State](https://assets-docs.agora.io/images/video-sdk/connection-state-main-web.svg) ##### Disconnection and reconnection [#disconnection-and-reconnection-3] During the communication process, if the user is disconnected due to network problems, the SDK automatically enables the disconnection and reconnection mechanism. The following figure shows the callbacks received by the local user `UID1` and the remote user `UID2` when: * A local user joins the channel * A network exception occurs * The connection is interrupted * The user rejoins the channel ![Disconnection Connection](https://assets-docs.agora.io/images/video-sdk/connection-state-web.svg) In the diagram: * **T0**: The Video SDK receives a `Client.join` request from `UID1`. * **T1**: `UID1` successfully joins the channel. `UID1` receives `AgoraRTCClient.on("connection-state-change")` callback reporting "CONNECTING" during joining channel and "CONNECTED" after joining. * **T2**: Due to the transmission delay between networks, `UID2` observes a delay of about 100 milliseconds for `UID1` to join the channel, and at this point `UID2` receives a `AgoraRTCClient.on("user-joined")` callback. * **T3**: At some point `UID 1` calls `AgoraRTCClient.publish` to publish the local track. * **T4**: `UID 2` receives the `AgoraRTCClient.on("user-published")` callback indicating that `UID 1` has published the track. `UID 2` can subscribe to `UID 1`'s track by calling `AgoraRTCClient.subscribe` method. * **T5**: If the `UID 1` network is interrupted during the communication process, the SDK automatically opens the disconnection and reconnection mechanism. * **T6**: The SDK triggers `AgoraRTCClient.on("connection-state-change")` callback to report "RECONNECTING" during automatic reconnection. * **T7**: If the Agora server does not receive the audio/video packet from `UID 1` for 10 consecutive seconds, the server determines that `UID 1` no longer publishes audio/video, and `UID 2` will receive `AgoraRTCClient.on("user-unpublished")` callback. * **T8**: If the Agora server does not receive a heartbeat packet from `UID 1` for 20 consecutive seconds, the server determines that `UID 1` is offline, and `UID 2` will receive the `AgoraRTCClient.on("user-left")` callback. * **T9**: After successfully re-establishing the connection, `UID 1` receives the `AgoraRTCClient.on("connection-state-change")` callback reporting as "CONNECTED". * **T10**: `UID 2` receives the `AgoraRTCClient.on("user-joined")` callback again. ## Reference [#reference-3] This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product. ### Connection states [#connection-states-3] The app may have the following connection states before joining, during a session, and after leaving a channel: | Connection state | Description | | :---------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **DISCONNECTED** | Connection disconnected. The SDK will not automatically reconnect while in this state. This state indicates that the user is in one of the following stages:- Has not joined the channel using `join`. - Has left the channel using `leave`. - Kicked out of the channel by the Agora server or failed to connect. | | **CONNECTING** | Joining. The instantaneous state after calling `join`. | | **CONNECTED** | Occurs after the app has successfully joined the channel. At this point the user can publish or subscribe to the audio and video in the channel. | | **RECONNECTING** | Occurs when the connection is interrupted due to a network disconnection or switch. The SDK automatically tries to reconnect after an interruption. | | **DISCONNECTING** | Disconnecting. This is the state when `leave` is called. | ### API reference [#api-reference-3] * [`AgoraRTCClient.on("connection-state-change")`](https://api-ref.agora.io/en/video-sdk/web/4.x/interfaces/iagorartcclient.html#event_connection_state_change) * [`AgoraRTCClient.on("user-joined")`](https://api-ref.agora.io/en/video-sdk/web/4.x/interfaces/iagorartcclient.html#event_user_joined) * [`AgoraRTCClient.on("user-left")`](https://api-ref.agora.io/en/video-sdk/web/4.x/interfaces/iagorartcclient.html#event_user_left) * [`AgoraRTCClient.on("user-published")`](https://api-ref.agora.io/en/video-sdk/web/4.x/interfaces/iagorartcclient.html#event_user_published) * [`AgoraRTCClient.on("user-unpublished")`](https://api-ref.agora.io/en/video-sdk/web/4.x/interfaces/iagorartcclient.html#event_user_unpublished)