User's Manual

Table Of Contents
iRouter Mode
AT+i Programmer‘s Manual Version 8.32 18-1
18 DHCP Server
iChip‘s DHCP server allows it to assign IP addresses and manage a network segment
when no DHCP server is available. iChip‘s DHCP server can handle a pool of up to 255
IP addresses concurrently. This may be usefull, for example, when iChip is configured to
operate in iRouter mode and provides access to the public internet via its modem
connection.
Two parameters govern DHCP server functionality:
DPSZ: The DHCP pool size parameter determines the range of IP addresses that
iChip allocates for its clients.
DSLT: The DHCP server lease time determines the lease time that iChip grants when
assigning IP addresses.
The DHCP server is activated under the following conditions:
An IP address is defined by the DIP parameter.
The DPSZ parameter is set to a value greater than 0.
Following a software reset (AT+iDOWN).
When activated, iChip‘s DHCP server assigns IP addresses starting from DIP+1 up to
DIP+DPSZ. In addition, the DHCP server offers the IP address stored in the IPG
parameter as a gateway to clients, and the mask address stored in its SNET parameter as a
Sub-Net. The assignment policy of iChip is as follows:
1. iChip attempts to assign the same IP for the same MAC address.
2. iChip starts re-using addresses only after using all the addresses in the pool.
3. iChip attempts to re-use the oldest expired address first.
4. iChip attempts to ping the address it is about to assign in order to avoid assigning
an address already used.
5. iChip offers its SNET parameter as a Sub-Net. If SNET is 0.0.0.0, iChip
calculates a new one according to address class.
6. iChip offers its IPG parameter as a gateway. If IPG is 0.0.0.0, iChip offers its IP
address as a gateway.
7. iChip offers the primary IP address of the Domain Name Server stored in its
DNS1 parameter to the client, provided it is not 0.0.0.0.