Sierra Wireless DART 200 CDPD Modem - page 79

DART 200 CDPD Modem User’s Guide 5 DART Supported Protocols
PN1197-00 Revision 1.0 5-25
A simplified block diagram of a terminal connection to a CDPD
network using the SLIP interface is shown in Figure 5-1.
Figure 5-1 Terminal connection to a CDPD network using SLIP
#1 #2 #3
MAS
(Terminal)
M-ES
MC-DART
CDPD
Network
AirLinkRS-232
Link
#1 - Local Terminal (MAS) IP Address
#2 - DART SLIP Interface IP Address
#3 - DART (registered NEI) IP Address
The three IP Addresses are:
1. Local Terminal (MAS) IP Address is set using by AT*Mn.n.n.n
This MAS address is not known to the CDPD network, so it is set by
convention to the same value as the one used for #3, as described in
item 3 on p. 5-25, to improve performance of the DART 200’s
routing mechanism and to ensure that FTP protocol works properly.
2. The DART SLIP Interface IP Address is set using the service
provider command AT^Sm.m.m.m
The SLIP IP Address is an arbitrary value, usually 1.1.1.2, because it
is only used by the MAS and DART 200 and is not known to the
network. In the definitions for commercially available stacks used
with SLIP this IP Address is referred to as the router, gateway, or
server address. This address must be present in SLIP definitions for
your stack or you cannot run SLIP with the DART 200.
There are two issues involving this address to consider:
• Some TCP/IP software stacks do a validity check on all of these
addresses and require them to be of the same class as the NEI
• The SLIP IP Address must be on a different subnetwork than the
NEI. If it is not, the DART cannot route packets (pings included)
to the CDPD network
The suggested resolution to these constraints (if 1.1.1.2 does not
work) is to set the network (class) portion of the DART SLIP address
to be off by one from the NEI’s network address, and to set the
device address to all ones, for example:
Class NEI SLIP Address
Class A 111.155.189.21 110.1.1.1
Class B 155.160.147.17 155.161.1.1
Class C 196.37.111.165 196.37.110.1