How to Use ADSL Modem to build a DHCP server?

Many people may not know how to use ADSL Modem to build DHCP servers. In Lan, IP Address Allocation is always a headache for administrators. After setting IP addresses for each client, you can change the IP address when you encounter "Good Guys". Either you cannot access the Internet or some software cannot run properly, causing a lot of unnecessary trouble. If we use the ADSL Modem to share the Internet, there is no need to manually specify the IP address of the client. As long as the built-in DHCP function of the ADSL Modem is enabled, the client can automatically obtain the IP address. The following is a detailed description of DHCP settings and Applications in ADSL Modem.

I. DHCP Overview

DHCP Dynamic Host Configuration Protocol) can automatically allocate available IP addresses for use within a limited lease period) and transmit additional IP address configuration information. DHCP is a protocol that enables the network administrator to centrally manage and assign IP information to all computers in a network. When DHCP is enabled in the network, you can use a device such as your ADSL Modem or a router) contact the ISP on the network to assign a temporary IP address to the computer in the network. The device assigned an IP address is called the DHCP server. The device that accepts the IP address is the DHCP proxy. When DHCP is enabled in the network, the dynamic allocation of IP address information is better than static allocation. When a DHCP Client reconnects to the network, you can assign a different IP address from the public IP address pool of the DHCP server.

DHCP allows us to use a central computer DHCP server) to manage and assign IP addresses over the network. If no DHCP is available, we have to configure IP addresses and related data for each computer separately.

2. Configure DHCP on the ADSL Modem

Go to the ADSL Modem configuration page, click "LAN port", and then click "DHCP Mode". On the "DHCP Settings" page, we can set three DHCP modes: none, DHPC Server, and DHCP Relay figure 1 ).

Figure 1 DHCP settings page

This ADSL Modem can be configured as a DHCP server, DHCP relay server, or DHCP proxy.

None: disable DHCP mode. If this mode is selected, the computer in the LAN must be set to the static IP address mode, that is, the specified IP address ).

DHCP Server: sets the ADSL Modem as a DHCP Server. If it is set as a DHCP server, the ADSL Modem allocates IP addresses to computers in the LAN according to the IP address protocol. If the assigned IP address is an address retained on the internet, you must also set the NAT network address translation function of the ADSL Modem, in this way, the IP addresses retained on the Internet can be translated into valid public IP addresses for use. In general, DHCP servers and NAT functions are enabled by default in ADSL Modem.

DHCP Relay: sets the ADSL Modem as a DHCP Relay server. If the ISP already provides the DHCP server function in our network, you can configure the ADSL Modem as a DHCP relay server. When the DHCP relay server receives a request from a computer on your network to access the Internet, it will contact the ISP to obtain the required IP information and then transfer the specific information to that computer.

If another computer or other device has the DHCP server function in our network, we can also configure the lanport of the ADSL Modem as the DHCP proxy for this server. When the ADSL Modem is configured as a DHCP proxy, it can be used as a DHCP server for computers in the LAN, but cannot be used for its own lanport. In "LAN Settings", select "External DHCP Server" to obtain the IP address from the ISP) or "Internal DHCP Server" refers to the IP address obtained from the DHCP Server of the Internal LAN) Fig 2 ).

Figure 2 LAN Settings page