# duplex

## Syntax

```
[no] duplex auto|half|full
```

## Syntax Description

<table><thead><tr><th width="203">Keyword</th><th>Description</th></tr></thead><tbody><tr><td><code>no</code></td><td>(Optional) Returns the interface duplex to its default value.</td></tr><tr><td><code>auto</code></td><td>The interface duplex mode is set via auto-negotiation.</td></tr><tr><td><code>half</code></td><td>The interface is placed into half-duplex mode.</td></tr><tr><td><code>full</code></td><td>The interface is placed into full-duplex mode.</td></tr></tbody></table>

## Defaults

Interface duplex is set via auto-negotiation by default.

## Usage Guidelines

This command can be used to force the duplex setting on an interface if autonegotiation is unavailable or undesirable.

If duplex is explicitly configured for an interface, the interface speed should also be explicitly configured. In other words, auto-negotiation should be enabled or disabled identically for both speed and duplex.

This command is valid only in interface context.

## Examples

```
duplex full
```

## Related Commands

{% content-ref url="interface" %}
[interface](https://docs.islandrouter.com/island-router-cli-2.3.2/commands/interface)
{% endcontent-ref %}

{% content-ref url="speed" %}
[speed](https://docs.islandrouter.com/island-router-cli-2.3.2/commands/speed)
{% endcontent-ref %}