Lantronix UDS1100 User's Guide download pdf (Page 76)

UDS1100 User Guide 76

Earlier chapters describe how to assign a static IP address using DeviceInstaller,

Web Manager, and Setup Mode (through a Telnet or serial connection). This section

covers other methods for assigning an IP address over the network.

DHCP

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

DHCP. If a DHCP server exists on the network, it provides the unit with an

IP address, gateway address, and subnet mask when the unit boots up.

You can use the DeviceInstaller software to search the network for the DHCP-

assigned IP address and add it to the list of devices retrieved.

Note: This DHCP address does not appear in the unit’s Setup Mode or in

Web Manager. You can determine your unit’s DHCP-assigned IP address in

Monitor Mode. When you enter Monitor Mode from the serial port with

network connection enabled and issue the NC (Network Communication)

command, you see the unit’s IP configuration.

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 obtain

an IP address automatically in smaller networks that may not have a DHCP server. A

range of IP addresses (from 169.254.0.1 to 169.254.255.1) has been explicitly

reserved for AutoIP-enabled devices. Do not use this range of Auto IP addresses

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. After reboot, the unit sends out

another ARP request to see if the selected address is in use, and so on.

AutoIP does not replace DHCP. The unit continues to look for a DHCP server on the

network. If it finds a DHCP server, the unit switches to the DHCP server-provided

address and reboots.

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.

AutoIP can be disabled by setting the unit’s IP address to 0.0.1.0. This setting

enables DHCP but disables AutoIP.

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Lantronix UDS1100 User's Guide Page 76