Re: [RTnet-developers] can I use netem on rtnet?

[Li C. <lic...@gm...>]

在 2008-09-01一的 22:45 +0200，Jan Kiszka写道：
> Li Chanjuan wrote:
> > hi,jan:
> >     
> >     I want to do a experiment on rtnet using netem and want to know that
> > how rtnet works when transmission error occurs. but after I setup rtnet,
> > I use:
> >   #tc qdisc add dev rteth0 root netem delay 1ms
> > there is error message: can't find "rteth0" device.
> > I use strace to find what happened, I got:
> > 
> > ioctl(4,SIOCGIFINDEX,{ifr_name="rteth0",..}) =-1(No such device)
> > 
> > I think this because rtnet is invisible to Linux, so tc can not work.
> 
> Exactly.
> 
> > 
> > Is it possible to use netem on rtnet? if it is, what should I do?
> 
> Nope, there is no (publicly known) implementation of a netem-like
> service on top of RTnet. However, it shouldn't be too tricky to write
> such support on top of RTnet's socket API.
> 
> On the other hand, I wonder why you need hard real-time guarantees for a
> "noise generator" like netem? Why is Linux itself unsuited?

what we interests is how rtnet will behave when there is communication
error. Now I redesign our experiement plan like this:
 ______        ________         _______
|       |      |       |        |      | 
| rtnet |----->|Linux  |------->| rtnet|
|_______|      |_______|        |______|

I use netem on the linux to simulate communication error between two
renet nodes. Then I will run some roundtrip test to see what happen.
Do you think such data make sence?


lily
thanks.

>