Technical information

Chapter 2: AT+i Commands Reference
May 31, 2008 AT+i Commands Reference Manual 2-47
IP Registration
When W24 goes online in a dial-up environment, it is normally assigned a dynamic IP address
during PPP establishment. Since a different IP address is usually assigned every session, it is not
practical to use W24 as a server, since the clients do not know what IP address to use.
Furthermore, under these restrictions, there is no practical way to know whether a specific system
is online or offline. A similar problem occurs when using the W24 WLAN, which is configured
to use a DHCP server. In this environment, a different IP address is usually assigned every time
the W24 boots and connects to the WLAN.
To overcome this problem, W24 incorporates built-in procedures designed to register its IP
address on a server system each time it goes online. Once registered, client systems may
interrogate the servers in order to verify the online status of a specific system and retrieve its
currently assigned IP address. The IP registration process is governed by several AT+i
parameters. Once these parameters are configured, W24 registers its IP address accordingly when
it goes online as a result of an explicit AT+i command (AT+iUP) or as a result of automated
Internet session establishment procedures, such as a triggered Internet session or when going
online as a SerialNET mode server.
In cases where W24 uses a NAT gateway to the Internet, it can be configured to register the
NAT's IP address and a special port that is linked to W24 in the NAT's configuration. See details
in the RRRL parameter description. When this is the case, the RRRL parameters (IP and port) are
used instead of the local IP and port values that W24 is assigned, in all registration methods
(RRMA, RRSV, and RRWS).
W24 includes several IP registration methods, as described below.
E-Mail Registration
W24 registers itself by sending an e-mail that contains its ID information and current IP address.
When the RRMA parameter contains an e-mail address, W24 sends an e-mail containing its
current IP address or its RRRL to the address defined in RRMA during the registration procedure.
The syntax of the e-mail body is:
<BDY parameter contents>
iChip-<D/L/S> S/N:<RP5> Version:<RP1> HN:<HSTN> IP:<IPA or RRRL>
Port:<LPRT or 80 or 0> http:// <IPA or RRRL><CR><LF>
The subject line of the e-mail is:
"RING RESPONSE LINK From: iChip-<D/L/S> S/N:<RP5> Version:<F/W
ver> HN:<HSTN> IP:<IPA or RRRL> Port:<LPRT or 80 or 0>"
where,
Port is LPRT if in SerialNET mode; 80 if not in SerialNET mode and AWS is enabled, and 0 if
not in SerialNET mode and AWS=0. The receiving end may refer to the contents of the subject
line to filter out this e-mail message.
Socket Registration
W24 registers itself by opening a socket to a registration server and sending its ID information
and current IP address. When W24's RRSV parameter contains a value, W24 establishes a socket