User's Manual

Table Of Contents
DHCP Client
AT+i Programmer‘s Manual Version 8.32 17-1
17 DHCP Client
A DHCP client component in iChip in LAN mode supports IP and server name
acquisition from a standard DHCP Server. The iChip device attempts to contact and
acquire server names from a DHCP server if and when its
DIP (Default IP) parameter
contains the special value 0.0.0.0.
When the DHCP acquisition procedure is successful, the iChip‘s
IPA (IP Address)
parameter contains the assigned IP address retrieved from the DHCP server. In addition,
server names relevant to iChip parameters are retrieved from the DHCP server, if and
only if they contain empty values at power-up (see table below). Parameters that contain
non-empty values retain those values. In addition, DNS values retrieved from the DHCP
server are retained as additional alternative DNS addresses when DNSn contain user-
defined values.
Parameter Name
Function
Empty Value
IPG
Gateway
0.0.0.0
SNET
Subnet Mask
0.0.0.0
DNS1
Primary Domain Name Server
0.0.0.0
DNS2
Secondary Domain Name Server
0.0.0.0
SMTP
Email Send Server
‗‘ (Empty String)
POP3
Email Receive Server
‗‘ (Empty String)
Table 17-1: Server Names Acquired from DHCP Server
All values acquired from the DHCP server are not retained as nonvolatile values. New
values shall be acquired during the next DHCP session, which will be activated during
the next iChip power-up, following a soft or hard reset or after the DHCP lease expires.
The DHCP client has two associated points in time when the DHCP server is contacted
for additional negotiations. At T1 (usually after half the original lease period), iChip
attempts to renew the lease period. If the renewal procedure fails, at T2 (usually after 7/8
the original lease period) iChip attempts to re-negotiate the lease. If the procedures at T1
and T2 fail and the lease expires, iChip continuously tries to locate a DHCP server for re-
negotiation. When this is the case, iChip stores 0.0.0.0 in the IPA parameter and cannot
communicate on the LAN until a DHCP server is found and IP and server names are
acquired.