Re: nam bug when using random loss modules

[Haobo Yu <haoboy@isi.edu>]

I think it should have been fixed in the current nam (and ns) snapshot.
Previously Simulator::lossmodel and SimpleLink::errormodule does not
generate any nam traces. You can manually add drop traces of error models,
however, nam does not show that correctly because of abnormal the
enqueue/drop order.

There are two solutions. First, if you are using ns snapshot you can use
Simulator::link-lossmodel to install the error model (which installs
an error model after the queue in a simple link), which allow any nam to
view the trace correctly. Second, if you still prefer installing an error
model before the queue in a simple link, you can download the current nam
snapshot, which contains a fix for that. 

- Haobo

On Tue, 9 Mar 1999, AL-HUSSEIN ABOU-ZEID wrote:

> 
> I've noticed that when you use nam with a model containing a two-state
> time-based loss model, the animation works correctly up till the first
> random loss, and after that it does strange things. One of these is that
> it shows a buffer size that is greater than the maximum buffer size
> allowed on the link (I am assuming this is a nam bug and not an ns bug).
> Another problem is that, after the first random loss, it might not show
> any packets getting through the link, as if the link remained in the bad
> state for the rest of the simulation time. However, this proves not true
> when checking the trace file, which implied a bug in the nam and not the
> ns.
> 
> I understand that the two-state and multi-state models are
> "under-developed" in the version I'm using (ns-v2.1b4a), so maybe someone
> would be interested in taking this problem into consideration in future ns
> releases.
> 
> Best Regards,
> 
>  --Hussein.
> ------------------
> Electrical Engineering Department
> University of Washington, Seattle.
>