---
title: Initialize Border
description: "Play 0x2B, server → client."
---

`play` · `0x2B` · **clientbound** (server → client)

Sends the full world border state: center `x`/`z`, old and new diameter, the `speed` in milliseconds to interpolate between them, the portal teleport boundary, and the warning distance and time. The server sends it after login and after a dimension change. The client creates its local world border from these values.

Sent by the server, read by the client. Listen for it with `client.on("InitializeBorder", (data) => …)` on the receiving side.

## Fields

| Field | Type | Notes |
|---|---|---|
| `x` | Double |  |
| `z` | Double |  |
| `oldDiameter` | Double |  |
| `newDiameter` | Double |  |
| `speed` | VarLong |  |
| `portalTeleportBoundary` | VarInt |  |
| `warningBlocks` | VarInt |  |
| `warningTime` | VarInt |  |

## Send it

```ts
await client.sendPacket("InitializeBorder", {
  x: /* Double */,
  z: /* Double */,
  oldDiameter: /* Double */,
  newDiameter: /* Double */,
  speed: /* VarLong */,
  portalTeleportBoundary: /* VarInt */,
  warningBlocks: /* VarInt */,
  warningTime: /* VarInt */,
});
```

Field aliases listed under Notes are accepted as alternative keys when writing.

Source: [`src/Core/Versions/776/Packets/play/clientbound/InitializeBorder.ts`](https://github.com/GDLev/mc-protocol/blob/master/src/Core/Versions/776/Packets/play/clientbound/InitializeBorder.ts)