RE: [ns] Trivial question about TCPSink

[Srihari Raghavan <sraghava@vt.edu>]

Hi,
  Thank you for your time. I noticed after my post that you had answered it
in one of the previous postings. Sorry about that.
  For others, in case one needs, here is the posting of the solution.
  http://mash.cs.berkeley.edu/dist/archive/ns-users/0003/0069.html

Thanks
Srihari Raghavan

-----Original Message-----
From: Lloyd Wood [mailto:l.wood@eim.surrey.ac.uk]
Sent: Thursday, April 26, 2001 6:17 PM
To: Srihari Raghavan
Cc: ns-users@ISI.EDU
Subject: Re: [ns] Trivial question about TCPSink


On Thu, 26 Apr 2001, Srihari Raghavan wrote:

> I am using a variation of the traditional dumbbell shaped topology with
> both UDP (CBR) sources and TCP (infinite FTP) sources. I am trying to mix
> these two traffic in a common bottleneck link that has less capacity than
> compared to the rate at which the sources generate traffic. When I
increase
> UDP traffic I expect TCP througphut over time to decrease due to the TCP
> congestion control.
>
> The question is that I need to collect bandwidth (in Mbps) at the
> TCPSink. With, Agent/LossMonitor sink for the UDP case, I use "bytes_" in
> the oft-repeated "record" function to collect statistics. With TCPSink I
do
> not have a similar data member.

You need to hack TCPSink's recv() function in the tcp-sink.cc file to
record the data you want, after introducing your own bound variables.
For the actual bytes received, numbytes in the tcp-sink file should
probably be a bound variable - but isn't. (note that header overhead
isn't counted, and doesn't exist anyway.)

There's a pointer to a (very simple, because I'm lazy) hack on my ns
webpage to record the rather different application-level throughput by
adding a recvBytes() method. This should probably increment a bound
variable called numbytesdelivered_ or somesuch.

TCPSink is generally neglected IMO.

L.

> I tried using the TCP agent's "ndatabytes_", but it gives the sender's
> view of the TCP bandwidth. What I need is the reciever's
> (TCPSink's) view of TCP bandwidth recieved over time. Do I need to use
> "acks" at the sender? Or is there any other way?
>
> Thank you for your time
> /Srihari
>
>

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>