# Active-Standby Failover<no value>

## Overview

Active/Standby is the simplest ASA failover mode. One unit actively processes traffic while the standby unit monitors and takes over if the active unit fails. Both units share the same configuration, and the standby unit does not pass traffic under normal operation.

**Key concepts:**
- Only one unit processes traffic at a time
- Stateful or stateless failover
- Failover link for health monitoring and configuration sync
- Optional state link for connection replication

## Video Walkthrough

*Video walkthrough coming soon.*

<!--  {{< youtube VIDEO_ID_HERE >}} -->

## Prerequisites

No additional licensing is required for Active/Standby failover. Both ASA units must have:

- Identical hardware model and module configuration
- Same software version
- Same firewall mode (routed or transparent)
- Same context mode (single or multiple)
- A dedicated failover link (LAN-based failover recommended)

## Configuration Steps (CLI)

### 1. Configure the Failover Interface

On the **primary** unit:

```text
ASAv1(config)# interface GigabitEthernet0/3
ASAv1(config-if)# no shutdown
```

### 2. Assign the Failover LAN Interface

```text
ASAv1(config)# failover lan unit primary
ASAv1(config)# failover lan interface folink GigabitEthernet0/3
ASAv1(config)# failover interface ip folink 10.0.0.1 255.255.255.252 standby 10.0.0.2
```

### 3. Configure the State Link (Optional but Recommended)

Using the same interface as the failover link:

```text
ASAv1(config)# failover link folink GigabitEthernet0/3
```

Or using a dedicated interface:

```text
ASAv1(config)# failover link statelink GigabitEthernet0/4
ASAv1(config)# failover interface ip statelink 10.0.1.1 255.255.255.252 standby 10.0.1.2
```

### 4. Enable Failover

```text
ASAv1(config)# failover
```

### 5. Configure the Secondary Unit

On the **secondary** unit, you only need to configure the failover interface and set it as secondary:

```text
ASAv1(config)# interface GigabitEthernet0/3
ASAv1(config-if)# no shutdown
ASAv1(config)# failover lan unit secondary
ASAv1(config)# failover lan interface folink GigabitEthernet0/3
ASAv1(config)# failover interface ip folink 10.0.0.1 255.255.255.252 standby 10.0.0.2
ASAv1(config)# failover
```

The secondary unit will pull the full configuration from the primary automatically.

### 6. Verify Failover Status

```text
ASAv1# show failover
ASAv1# show failover state
```

## Configuration Steps (ASDM)

*Screenshots and ASDM walkthrough coming soon.*

<!-- 
Add ASDM screenshots here as you create them:
![Step 1](images/asdm-step1.png)
-->