35. TCP Agents

This section describes the operation of the TCP agents in ns. There are two major types of TCP agents: one-way agents and a two-way agent. One-way agents are further subdivided into a set of TCP senders (which obey different congestion and error control techniques) and receivers (``sinks''). The two-way agent is symmetric in the sense that it represents both a sender and receiver. It is still under development.

The files described in this section are too numerous to enumerate here. Basically it covers most files matching the regular expression ~ns/tcp*.{cc, h}.

The one-way TCP sending agents currently supported are:

• Agent/TCP - a ``tahoe'' TCP sender
• Agent/TCP/Reno - a ``Reno'' TCP sender
• Agent/TCP/Newreno - Reno with a modification
• Agent/TCP/Sack1 - TCP with selective repeat (follows RFC2018)
• Agent/TCP/Vegas - TCP Vegas
• Agent/TCP/Fack - Reno TCP with ``forward acknowledgment''
• Agent/TCP/Linux - a TCP sender with SACK support that runs TCP congestion control modules from Linux kernel

The one-way TCP receiving agents currently supported are:

• Agent/TCPSink - TCP sink with one ACK per packet
• Agent/TCPSink/DelAck - TCP sink with configurable delay per ACK
• Agent/TCPSink/Sack1 - selective ACK sink (follows RFC2018)
• Agent/TCPSink/Sack1/DelAck - Sack1 with DelAck

The two-way experimental sender currently supports only a Reno form of TCP:

• Agent/TCP/FullTcp

The section comprises three parts: the first part is a simple overview and example of configuring the base TCP send/sink agents (the sink requires no configuration). The second part describes the internals of the base send agent, and last part is a description of the extensions for the other types of agents that have been included in the simulator.