buffer size

[Haobo Yu]

> - How to change the buffer size for a link

Link does not have a buffer, queue does. Use Simulator::queue-limit{} (in
tcl/lib/ns-lib.tcl). 

> - How to set the file size in an ftp application (now, I am using  $ftp
> send ($ftp_volume)

That should work right? 

> - How to calculate the average file transfer time for this ftp file

You can either post-process trace files, or you can use TCP's done{}
method, which is called when data transfer is complete. Please see
tcl/test/test-suite-rbp.tcl for an example. 

- Haobo