7.3 Transmission Control Protocol (TCP)
The QualNet TCP model is based on RFC 793, RFC 2481, and RFC 1323.
7.3.1 Description
The Transmission Control Protocol (TCP) is a highly reliable host-to-host
protocol between hosts in packet-switched computer communication networks,
and in interconnected systems of such networks. The TCP fits into a layered
protocol architecture just above IP which provides a way for the TCP to send
and receive variable-length datagrams.
QualNet's TCP model uses code converted from the FreeBSD 2.2.2 source code
implementation for TCP.
The differences between the QualNet code and the FreeBSD code are improvements
for simulation performance, configurability through QualNet configuration
files and GUI, interface code to the simulator, and modifications to offer
additional variants of TCP. FreeBSD's TCP variant is known as "TCP Lite".
TCP Versions
There are several versions of TCP that you can specify via the QualNet
configuration file: TCP Lite, TCP NewReno, TCP Reno, TCP SACK, and TCP Tahoe.
These are modified in real systems by using compiler directives to enable
sections of code, and then recompiling the kernel. Some operating systems
also provide ways to dynamically modify some of the TCP parameters at runtime.
In QualNet, change them by editing the configuration file. You can either
modify these parameters individually, or you can select one of the well
known TCP versions that will automatically activate the appropriate parameters.
TCP Lite is the default variant of TCP for QualNet.