AirPrime - TCP-IP and Internet Library 5.54 - Development Guide

Sierra Wireless customers are provided with an advanced set of APIs that give them complete IP connectivity control. This allows an application to communicate using IP connectivity on different types of bearers (UART, GSM, GPRS, and EDGE) simultaneously.

The Sierra Wireless Software Suite also supports "pure" IP APIs which can provide better capabilities
and control.  The socket abstraction layer gives high-level access to communication abilities, through a channel and its dedicated API. The following types of channels are implemented:

• A TCP channel implementation, which allows users to create and use client and server TCP sockets
• A UDP channel implementation, which allows users to create and use UDP sockets
• A PING channel implementation, which allows users to configure and send ICMP ECHO requests, or “pings”, and to receive feedback on response times, routing errors or timeout errors

The bearers are handled by the bearer manager which provides IP connectivity using various links. Several bearers can be activated simultaneously. The following links are currently supported:

• GSM data
• GPRS
• Direct connection on an UART
• Ethernet bearer

Features of the TCP/IP protocol Stack include:

• IP, ICMP, UDP, TCP Protocols
• All RFC 1122 requirements for host-to-host interoperability
• Fragmentation and reassembly of IP datagrams
• Support for multiple network interfaces (forwarding of packets between interfaces is not enabled by default)
• Loopback interface

Socket Layer:

• Configuration of socket receive and send buffers
• Control of some IP header fields such as TTL, TOS, "Don‟t fragment" flag

TCP Sockets:

• Congestion control (slow start, congestion avoidance, fast retransmit and fast recovery)
• Option for disabling the Naggle algorithm
• Immediate notification of all connection state changes
• Support for normal connection termination and reset of the connection

DNS Resolver:

• Integrated into the socket abstraction layer
• Support for primary and secondary DNS servers

The PPP is required by GSM and UART bearers, the following features are supported:

• Client and server mode
• Authentication using PAP, CHAP, MS-CHAPv1 or MS-CHAPv2
• Auto-configuration of IP address, primary and secondary DNS servers