Implementation of Token Bucket Filter in ns3

Implementation of Token Bucket Filter in ns3

[Surya Seetharaman, 2017-07-28 17:28:56]

This patch contains the implementation of the Token Bucket Filter QueueDisc in
ns3 along with a user example, test suite and documentation. It has been
developed as a part of the Google Summer of Code 2017 project.

Any suggestions/reviews would be appreciated. 

Thanks,
Surya.

[Tom Henderson, 2017-09-04 14:44:11]

https://codereview.appspot.com/326150043/diff/1/examples/traffic-control/tbf-...
File examples/traffic-control/tbf-example.cc (right):

https://codereview.appspot.com/326150043/diff/1/examples/traffic-control/tbf-...
examples/traffic-control/tbf-example.cc:37: // of 10000 packets.
Why such a large value?  It does not seem operationally realistic.

https://codereview.appspot.com/326150043/diff/1/examples/traffic-control/tbf-...
examples/traffic-control/tbf-example.cc:105: "QueueLimit", UintegerValue
(6553500),
Why are you using this unusual constant '65535000'?  Where does the value come
from?  Please document.

https://codereview.appspot.com/326150043/diff/1/examples/traffic-control/tbf-...
examples/traffic-control/tbf-example.cc:110: // Add the internal queue used by
Tbf
Please add a comment that this second statement is optional, only if user wants
to separately provide and configure the internal queue.

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/doc/tbf.rst
File src/traffic-control/doc/tbf.rst (right):

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/doc/tbf.r...
src/traffic-control/doc/tbf.rst:11: TBF is a simple classless qdisc that allows
controlling the bandwidth of the throughput according
output

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/doc/tbf.r...
src/traffic-control/doc/tbf.rst:22: 2. Data rate < Token rate : Very less number
of tokens are depleted.
s/Very less number of/Fewer

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/doc/tbf.r...
src/traffic-control/doc/tbf.rst:94: The key attributes that the CoDelQueue class
holds include the following:
s/CoDelQueue/TbfQueueDisc

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/doc/tbf.r...
src/traffic-control/doc/tbf.rst:102: 
Please add a section

TraceSources
============

to document them

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
File src/traffic-control/model/tbf-queue-disc.cc (right):

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
src/traffic-control/model/tbf-queue-disc.cc:70: UintegerValue (0),
Add a comment that the special value of zero, if used with a PeakRate of zero,
will disable the second bucket.

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
src/traffic-control/model/tbf-queue-disc.cc:79: "Speed at which tokens enter the
second bucket in bps or Bps.",
Add a documentation string that the special value of data rate == 0 is
interpreted as infinite.

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
src/traffic-control/model/tbf-queue-disc.cc:399: m_mtu = GetNetDevice ()->GetMtu
();
CheckConfig() should not perform queue configuration in general, because it is
called once at initialization-- try to make it 'check' but not 'configure'.

What happens if m_peakRate is set after object Initialize time?  Will the queue
work correctly?  Try to move code like this into the setter methods instead.

Or, you could consider to add CheckConfig() statement at the end of each setter
method; will that work?

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
File src/traffic-control/model/tbf-queue-disc.h (right):

https://codereview.appspot.com/326150043/diff/1/src/traffic-control/model/tbf...
src/traffic-control/model/tbf-queue-disc.h:141: * \brief Set the speed of the
tokens entering the first bucket in bps or Bps.
Please delete 'in bps or Bps' when referring to DataRate objects (here, and in
the methods below).

DataRate::GetBitRate() returns a rate in bps, but DataRate is an object
representing the data rate.

Also, globally, s/speed/rate