Instruction manual
28
13. Initial Ethernet Configuration
The gateway typically requires configuration prior to communicating on an
Ethernet network. This fundamental configuration is achieved via one of two
possible methods: using ICMP (“ping”) configuration via the Address Resolution
Protocol (ARP), or via a text-based console interface, accessible over the
RS232 serial channel and a telnet interface. The following are the factory-set
values of the most important Ethernet parameters:
IP Address.........................192.168.1.100
Subnet Mask .....................255.255.255.0
Default Gateway................192.168.1.2
If these parameters are not compatible with your network settings, they will
need to be modified.
13.1 ARP Method
The IP address can be changed remotely by using the Address Resolution
Protocol (ARP). This is performed by adding a static entry into a PC’s ARP
cache table, which stores the associations between a device’s IP and physical
(MAC) addresses. The unit is then “pinged” from a command prompt (MS
DOS™ window) to assign the new IP address to it. Below is an example of the
commands used to change the unit’s IP address:
arp -s <IP address> <MAC address>
ping <IP address>
arp -d <IP address>
The initial “arp –s” command adds a static association between the unit’s MAC
address and the desired IP address to the PC’s ARP table. When the ping
command is executed with the IP address as an argument, the PC sends this
information to the unit indicated by the associated MAC address. The unit then
detects that it was addressed with the correct MAC address and adopts the IP
address indicated in the ICMP “ping” packet. The optional “arp –d” command
then removes the static route from the PC’s ARP table.
The unit’s MAC address is printed on a label located to the left of the Ethernet
jack on the unit’s cover. An example of setting a unit’s IP address to
192.168.16.110 would look like:
arp -s 192.168.16.110 00-90-C2-C0-29-8B
ping 192.168.16.110
arp –d 192.168.16.110
Forcing the unit to adopt the new IP address completes only half of the ARP
configuration process. In addition to the IP address being changed, the unit
also automatically configures its subnet mask to 255.255.255.255. This setting