# compression

Hot Reloadable

Defines the type compression mode to use between routes.

If set to `on`, it will use the `s2_fast` compression.

## Types

| Type     | Description                                                                                                                                                                                                                                                                                                                                                                                                   | Choices                                                                                    |
| -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |
| `string` | The compression mode dictates if and how compression is applied for a connection. The value of `accept` indicates it will inherit the mode of the server it is connecting to. If both have `accept`, no compression will be used. The `s2_fast`, `s2_better`, and `s2_best` modes indicate the level of S2 compression used. `s2_auto` will dynamically change the compression level based on RTT thresholds. | `disabled`, `off`, `enabled`, `on`, `accept`, `s2_fast`, `s2_better`, `s2_best`, `s2_auto` |
| `object` | An object with a set of explicit properties that can be set.                                                                                                                                                                                                                                                                                                                                                  | -                                                                                          |

## Properties

| Name                                                                        | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                        | Type       | Default             | Reloadable |
| --------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------- | ------------------- | ---------- |
| [`mode`](/reference/config/cluster/compression/mode.md)                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | `string`   | -                   | Yes        |
| [`rtt_thresholds`](/reference/config/cluster/compression/rtt_thresholds.md) | Applies only when the `s2_auto` mode is used and defines the round-trip time (RTT) thresholds for compression level changes. By default, no compression is used unless the RTT hits the first threshold (e.g. 10ms), then `s2_fast`. The next threshold would switch to `s2_better`, and then finally `s2_best` is the last threshold is reached. Note, the compression level is dynamic so if the RTT decreases, the compression level will decrease accordingly. | `duration` | `[10ms 50ms 100ms]` | Yes        |