Technical information

DHCP Server
2-50 AT+i Commands Reference Manual May 31, 2008
DHCP Server
W24's DHCP server allows it to manage a network segment when no DHCP server is available.
When W24 is configured to operate in iRouter mode, it provides access to the public internet via
its modem connection. The DHCP server can handle up to 255 IP addresses concurrently.
Two parameters govern DHCP server functionality:
• DPSZ: The DHCP pool size parameter determines the range of IP addresses that W24
allocates for its clients.
• DSLT: The DHCP server lease time determines the lease time that W24 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, W24'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 W24 is as follows:
1. W24 attempts to assign the same IP for the same MAC address.
2. W24 starts re-using addresses only after using all the addresses in the pool.
3. W24 attempts to re-use the oldest expired address first.
4. W24 attempts to ping the address it is about to assign in order to avoid assigning an address
already used.
5. W24 offers its SNET parameter as a Sub-Net. If SNET is 0.0.0.0, W24 calculates a new one
according to address class.
6. W24 offers its IPG parameter as a gateway. If IPG is 0.0.0.0, W24 offers its IP address as a
gateway.
7. W24 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.