In the complex network environment of the Industrial Internet of Things (IIoT), ensuring stable connection and efficient communication of devices is the cornerstone of building a reliable system. As a key device for connecting internal and external networks, the configuration and management of LTE 4G Router directly affect the performance and security of the entire network. Among them, the DHCP dynamic host configuration protocol and the setting of reserved IP addresses are important parts of the configuration of Lte 4g Router. This article will delve into the knowledge related to DHCP and reserved IP in LTE 4G Router, and explore its practical application in industrial networking applications.

1. What is DHCP

DHCPDynamic Host Configuration Protocol, also known as dynamic host configuration protocol, is a network protocol used to simplify network configuration for hosts. It allows servers in the network to automatically allocate network configuration information such as IP addresses, subnet masks, default gateways, and DNS server addresses to DHCP clients such as computers, printers, and industrial devices, thereby reducing the workload of network administrators and improving the efficiency of network configuration.

2. The working principle of DHCP

The workflow of DHCP is roughly as follows:

• DHCP discovery: DHCP client broadcasts a DHCP discovery message in the network to request the DHCP server to provide network configuration information.
• DHCP Offer: After receiving the discovery packet, the DHCP server selects an IP address from the available IP address pool and encapsulates it along with other network configuration information in a DHCP offer packet, which is then sent to the DHCP client.
• DHCP request: After receiving the offer message, the DHCP client will select a DHCP server that is usually the first received to respond and send a DHCP request message to confirm the selected network configuration information.
• DHCP confirmation: After receiving the request message, the DHCP server will send a DHCP confirmation message to the DHCP client to formally confirm the allocation of network configuration information.

3. Overview of Reserved IP

3.1 Definition of Reserved IP

Reserved IP addresses refer to IP addresses pre-allocated to specific devices in the network. These addresses are excluded from the DHCP server's IP address pool, meaning they are not automatically assigned to other devices by the DHCP server. Reserved IP addresses are usually used for devices that require fixed IP addresses, such as servers, printers, industrial control devices, and so on.

3.2 The role of reserved IP

• Stability: Assigning fixed IP addresses to critical devices can prevent network interruptions or service unavailability caused by IP address conflicts or changes.
• Security: By restricting access to reserved IP addresses, network security can be improved and unauthorized devices prevented from accessing the network.

Convenience in management: The fixed IP address makes it easier for network administrators to identify and manage devices in the network, facilitating troubleshooting and remote maintenance.

4. Application practice of DHCP and reserved IP in Lte 4g Router

4.1 DHCP configuration in Lte 4g Router

When configuring DHCP in the Lte 4g Router, it is necessary to set parameters such as the IP address pool, lease time, default gateway, and DNS server for the DHCP server. In addition, it is also necessary to consider the security issues of DHCP, such as enabling the DHCP Snooping function to prevent DHCP spoofing attacks.

4.2 Keep the IP settings in the Lte 4g Router

When setting up a reserved IP address in the Lte 4g Router, it is usually necessary to specify the IP address to be reserved and the corresponding MAC address physical address in the configuration interface of the DHCP server. In this way, when the device with this MAC address requests DHCP service, the DHCP server will automatically allocate a specified reserved IP address to the device.

4.3 Application Scenario Examples

• Industrial control equipment: For industrial control equipment that requires real-time communication and stable connectivity, it is possible to set up a reserved IP address for it to ensure that it can always use a fixed IP address for network communication.
• Video surveillance system: In a video surveillance system, cameras usually require fixed IP addresses for remote access and management. By setting a reserved IP address for the camera, stable transmission of video data and smooth real-time monitoring can be ensured.
• Server and key equipment: In the industrial IoT environment, servers and key equipment such as PLC and DCS usually require fixed IP addresses to support critical business applications. Setting a reserved IP address for these devices can improve network reliability and security.

DHCP and reserved IP are important parts of the configuration of LTE 4G Router, which together form the foundation for stable and efficient operation of the industrial IoT network. By reasonably configuring DHCP servers and setting reserved IP addresses, the allocation and management of network resources can be optimized, and the performance and security of the network can be improved. For industrial IoT users who need to use networking applications, it is crucial to have a deep understanding and grasp of DHCP and reserved IP. Only in this way can we build a stable, reliable and secure industrial IoT network, providing strong support for the digital transformation and intelligent upgrading of enterprises.