[R-C] Congestion Control BOF

[Varun Singh]

On Wed, Oct 12, 2011 at 18:25, Henrik Lundin <henrik.lundin at webrtc.org> wrote:
>
>
> On Tue, Oct 11, 2011 at 5:17 PM, Randell Jesup <randell-ietf at jesup.org>
> wrote:
>> On 10/11/2011 3:11 AM, Henrik Lundin wrote:
>>>
>>> Randell,
>>>
>>> This is a good start, indeed! Some comments on the details of your
>>> initial email are below.
>>
>> Thanks!
>>
>>> About simulation: Does anyone have any suggestions for suitable
>>> simulation tools? ns2 is one choice of course, but I'm not very pleased
>>> with it.
>>
>> I don't have strong opinions; I've used both dummynet (for simple testing,
>> though the latest ones are better for simulating variable delay and loss),
>> and NetEm, which I'm not an expert with, but at least provides normal
>> distributions of delay, correlation of delays/loss, etc.  You'd need to use
>> it with a rate control discipline to model a router/NAT/modem.
>>
>> For modern uses of dummynet in PlantLab, etc see
>> http://info.iet.unipi.it/~luigi/dummynet/
>> and
>> http://info.iet.unipi.it/~luigi/papers/20100316-cc-preprint.pdf
>>
>> More comments in-line...
>
> I was primarily looking for offline simulation tools. NetEm and dummynet are
> both tools for emulating network impairments to real-time traffic, right?
>>

NetEm and Dummynet can emulate network characteristics like change in
link capacity, one-way delay, bit-error rate. One can enable these
characteristics on a specific source interface/ip address or port or
apply it to outgoing or incoming packets. I think even to specific
protocols such as just TCP or UDP.

We have run simulations using ns2 but they take a lot of time because
ns2 is event driven and therefore the clock is not real-time (not in
sync with system clock). A 10 minute video call may take any where
from 1-3 hrs or even longer  to simulate depending on the scenario
(number of cross traffic, type of simulation etc.). Our code is not
available but some researchers use EvalVid-RA for NS2. The sources are
available at http://www.item.ntnu.no/~arnelie/Evalvid-RA.htm.