On Wed, Oct 12, 2011 at 18:25, Henrik Lundin <henrik.lundin@webrtc.org> wrote:
On Tue, Oct 11, 2011 at 5:17 PM, Randell Jesup <randell-ietf@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.