# Bind a L2 VIP to PostgreSQL Primary with VIP-Manager

LLMS index: [llms.txt](/llms.txt)

---

You can define an **OPTIONAL** L2 VIP on a PostgreSQL cluster, provided that all nodes in the cluster are in the same L2 network.

This VIP works on Master-Backup mode and always points to the node where the primary instance of the database cluster is located.

This VIP is managed by the [VIP-Manager](https://github.com/cybertec-postgresql/vip-manager), which reads the Leader Key written by Patroni from DCS (etcd) to determine whether it is the master.


------

## Enable VIP

Define [`pg_vip_enabled`](/docs/pgsql/param#pg_vip_enabled) parameter as `true` in the cluster level to enable the VIP component on the cluster. You can also enable this configuration in the global configuration.

```bash
# pgsql 3 node ha cluster: pg-test
pg-test:
  hosts:
    10.10.10.11: { pg_seq: 1, pg_role: primary }   # primary instance, leader of cluster
    10.10.10.12: { pg_seq: 2, pg_role: replica }   # replica instance, follower of leader
    10.10.10.13: { pg_seq: 3, pg_role: replica, pg_offline_query: true } # replica with offline access
  vars:
    pg_cluster: pg-test           # define pgsql cluster name
    pg_users:  [{ name: test , password: test , pgbouncer: true , roles: [ dbrole_admin ] }]
    pg_databases: [{ name: test }]

    # Enable L2 VIP
    pg_vip_enabled: true
    pg_vip_address: 10.10.10.3/24
    #pg_vip_interface: auto
```

Beware that [`pg_vip_address`](/docs/pgsql/param#pg_vip_address) must be a valid IP address with subnet and available in the current L2 network.

[`pg_vip_interface`](/docs/pgsql/param#pg_vip_interface) defaults to `auto`, in which case Pigsty detects the interface for each instance from the IPv4 address in the inventory.

If auto-detection is unsuitable for non-standard or policy-routing environments, explicitly specify a valid interface name for each instance, for example:

```yaml
pg-test:
  hosts:
    10.10.10.11: { pg_seq: 1, pg_role: primary , pg_vip_interface: eth0  }
    10.10.10.12: { pg_seq: 2, pg_role: replica , pg_vip_interface: eth1  }
    10.10.10.13: { pg_seq: 3, pg_role: replica , pg_vip_interface: ens33 }
  vars:
    pg_cluster: pg-test           # define pgsql cluster name
    pg_users:  [{ name: test , password: test , pgbouncer: true , roles: [ dbrole_admin ] }]
    pg_databases: [{ name: test }]

    # Enable L2 VIP
    pg_vip_enabled: true
    pg_vip_address: 10.10.10.3/24
```

To refresh the VIP configuration and restart the VIP-Manager, use the following command:

```bash
./pgsql.yml -t pg_vip
```