Need help with tcp simulation model!

[Jorden Kerkhof]

Dear reader,

For my graduation project I have to design network device hardware. Before I start creating a VHDL model for this, I first want to test and verify some parameters in a simplified network model. I have not much experience in networking and network simulators as well. I found this NS3 to be a modular network simulator which I think can create my system. Only I need some help with this, because I am not comfortable in programming in C++. The simplified system I want to simulate can be found in the attachment. I will explain the concept:

Node 1

Node 1 will have to act as an TCP-source which will sent an inifinite amount of data to Node 2 over an ethernet link. I want to control the following paramters:

• TCP parameters:
• Congestion control algorithm
• Recovery algorithm
• TCP-options (like SACK, Timestamp, Wscale)
• Sending datarate
• Ethernet link parameters
• Bandwidth
• Delay

Node 2

The second node will have 2 applications running.

1. Application 1 will act as a TCP Sink and receive all the packets from node 2 and Acknowledge them. 
2. Application 2 will send all packets received from node 1 to node 3. (Linktype doesn't matter) 

Node 3

The third node will have also 2 applications running:

1. Application 1 will receive all the packets coming from node 2 and store them in a buffer
2. Application 2 will act as an TCP source which will send all the data from the buffer to node 4 using TCP. For this TCP source I want to adjust the following parameters.
• Recovery Algorithm
• TCP-Options (SACK, Timestamp, Wscale)
• Buffersize of node 3

Node 4 

This node will solely act as a TCP-sink, only receiving packets from node 3 and acknowledge them.

I don't know how to create an node such as node 2 or 3. Is there somebody who can  help me?

Also when I run a simple Server-Client simulation with a datarate of  100Mbps it takes almost 25 (!!) minutes to run.  See the "test-tahoe.cc" file. Is this normal to take so long to finish?