gtpc1m1dTransmission Control Protocol/Internet Protocol

Components of TCP/IP Native Stack Support

Figure 15 provides an overview of the TCP/IP native stack support components.

Figure 15. TCP/IP Native Stack Support Components


Socket application
The user application or TPF middleware that issues socket application programming interface (API) functions.

Socket API processing
Processes socket API functions. For calls that require packets to be sent out, the IP send component is called. For calls to read data, and the necessary data has already been received from the network, the call is processed completely by this layer.

IP send
Builds all packets and adds them to the IP output queue to send them to the network, or sends the packets directly to the OSA-Express card. If a large amount of CDLC output packets exist, a write channel program will be issued if an available IP router is found to write out the packets immediately (rather than wait for polling to write out the packets).

IP scan
Activated several times per second to poll the network (send and receive packets) and retransmit lost TCP output messages.

IP trace read processing
Activated when packets are received from the IP network. Initial processing of a packet is done to identify the socket that the packet is destined for, process TCP connection requests, and stand-alone acknowledgments of TCP data. Packets containing user data are passed via the TPF input list to IP Opzero for further processing.

IP Opzero
Reassembles fragmented packets and then passes the entire message to the appropriate protocol layer.

TCP Opzero
Processes data received for stream sockets. This includes processing out-of-order data and acknowledging the receipt of data.

UDP Opzero
Processes data received for datagram sockets.

RAW Opzero
Processes data received for RAW sockets. This includes processing ICMP requests (like PING requests), ICMP error messages, and user-created RAW sockets.