Lantronix 10 manual Dhcp, AutoIP

Getting Started

2.3.1 DHCP

The unit ships with a default IP address of 0.0.0.0, which automatically enables DHCP.

Provided a DHCP server exists on the network, it will assign the unit an IP address, gateway address, and subnet mask when the unit boots up. The DR1 has acquired an IP address if the red LED stops flashing and the green Status LED is on continuously. (If no DHCP server exists, the unit responds with a diagnostic error: the red Diagnostic LED blinks continuously, and the green Status LED blinks five times. This blinking only continues for about 15 seconds.)

You can use the DeviceInstaller software to search the network for the IP your unit has been assigned by the DHCP server and add it to the managed list. See Add the Unit to the Manage List later in this chapter.

Note: This DHCP address will not appear in the unit’s standard configuration screens. You can determine your unit’s DHCP-assigned IP address from the DHCP server, or in Monitor Mode. When you enter Monitor Mode from the serial port with network connection enabled and issue the NC (Network Communication) command, you will see the unit’s IP configuration.

2.3.2 AutoIP

The unit ships with a default IP address of 0.0.0.0, which automatically enables Auto IP within the unit. AutoIP is an alternative to DHCP that allows hosts to automatically obtain an IP address in smaller networks that may not have a DHCP server. A range of IP addresses (from 169.254.0.1 to 169.254.255.254) has been explicitly reserved for AutoIP-enabled devices. The range of Auto IP addresses is not to be used over the Internet.

If your unit cannot find a DHCP server, and you have not manually assigned an IP address to it, the unit automatically selects an address from the AutoIP reserved range. Then, your unit sends out a (ARP) request to other nodes on the same network to see whether the selected address is being used.

•If the selected address is not in use, then the unit uses it for local subnet communication. 

•If another device is using the selected IP address, the unit selects another address from the AutoIP range and reboots itself. After reboot, the unit sends out another ARP request to see if the selected address is in use, and so on.

AutoIP is not intended to replace DHCP. The unit will continue to look for a DHCP server on the network. If a DHCP server is found, the unit will switch to the DHCP server-provided address and reboot.

Note: If a DHCP server is found, but it denies the request for an IP address, the unit does not attach to the network, but waits and retries.

2-4 UDS-10 User Guide