> For the complete documentation index, see [llms.txt](https://fancyloves.gitbook.io/openshift/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fancyloves.gitbook.io/openshift/route/keepalived.md).

# keepalived

For each VIP, keepalived keeps the state of the node. The VIP on the node may be in **MASTER**, **BACKUP**, or **FAULT** state.

Keepalived is in **MASTER** state when it is servicing the VIP, in **BACKUP** state when another node is servicing the VIP, or in **FAULT**\` state when the check script fails.

All VIPs on the node that are not in the **FAULT** state participate in the negotiation to decide which will be MASTER for the VIP. All of the losers enter the **BACKUP** state. This negotiation is done by all the keepalived daemons and it determines which nodes will service which VIPs.

When the check script on the **MASTER** fails, the VIP enters the **FAULT** state and triggers a renegotiation. When the **BACKUP** fails, the VIP enters the **FAULT** state.

When a host leaves the **FAULT** state by passing the check script, the host becomes a **BACKUP** if the new host has lower priority than the host currently in the **MASTER** state.

When the check script passes again on a VIP in the **FAULT** state, it exits **FAULT** and negotiates for **MASTER**. The resulting state is either **MASTER** or **BACKUP**.

Keepalived monitors the health of the application by periodically running an optional user supplied check script. the script can test a web server by issuing a request and verifying the response.

When a host running Keepalived passes the check script, the host can become in the MASTER state based on its priority and the priority of the current MASTER, as determined by the preemption strategy.

This pod runs Keepalived which uses **VRRP (Virtual Router Redundancy Protocol)** among all the Keepalived daemons to ensure that the service on the watched port is available, and if it is not, Keepalived will automatically float the VIPs.

Each ipfailover pod managed by the ipfailover deployment configuration (1 pod per node/replica) runs a keepalived daemon.

Create IP failover deployment configuration, by running the

```
oc adm ipfailover command.
```

```
$ oc adm ipfailover --selector="router=us-west-ha" \
    --virtual-ips="1.2.3.4,10.1.1.100-104,5.6.7.8" \
    --watch-port=80 --replicas=4 \
    --check-script=<script> \
    --check-interval=<seconds> \
    --create
```

the command below will create an IP failover configuration on a selection of nodes labeled router=us-west-ha (on 4 nodes with 7 virtual IPs monitoring a service listening on port 80, such as the router process).

* The script must exit with 0 for PASS or 1 for FAIL. By default, the check is done every two seconds, but can be changed using the --check-interval=\<seconds> option.&#x20;
* When a check script is not provided, a simple default script is run that tests the TCP connection.  This default test is suppressed when the monitor port is 0.

there are ipfailover, router, and geo-cache pods on each node. The set of VIPs for each ipfailover configuration must not overlap and they must not be used elsewhere in the external or cloud environments.