What is BOOTP?
BOOTP stands for Bootstrap Protocol and is a network protocol through which devices automatically obtain an IP address and network configuration at startup, before they are fully initialised.
BOOTP was originally developed to provide a network configuration for diskless workstations. Today it has largely been replaced by DHCP, but it is still used in industrial environments.
🧠 How does BOOTP work?
- A device without an IP address sends a BOOTP request (broadcast) at startup.
- A BOOTP server answers the request with:
- A fixed IP address (based on the MAC address)
- Subnet mask, gateway, and optionally a boot file path (e.g. firmware)
- The device uses this information to begin network communication.
🏭 Use of BOOTP in industrial networks
- Many industrial devices such as PLCs, IO modules, Drives and HMIs still support BOOTP for simple initial IP configuration.
- BOOTP is useful at first installation or after a factory reset.
- Some manufacturers offer their own BOOTP tools for configuration (e.g. Siemens, Rockwell).
🔍 BOOTP vs. DHCP
| Aspect | BOOTP | DHCP |
|---|---|---|
| Dynamic | No — fixed IP based on MAC address | Yes — dynamic, with optional reservations |
| Lease time | Not supported | Yes — IP addresses are temporary |
| Complexity | Simple, static | More flexible and feature-rich |
| Usage | Legacy / industrial | General, modern network management |
| Compatibility | Many DHCP servers also support BOOTP | DHCP clients do not necessarily work with BOOTP servers |
🔐 Security considerations
- BOOTP is not encrypted or authenticated
- MAC spoofing can lead to incorrect IP assignments
- Limit broadcast traffic via VLAN or firewall rules
- In OT networks, network segmentation is essential when using BOOTP
📌 In summary
BOOTP is an older but still widely used protocol for automatic IP configuration, particularly in industrial installations. While simple and effective, it is increasingly being replaced by DHCP for flexibility and manageability.