[Netkit.users] problem when simulating link/node down on Netkit

[Xu Yao]

Hello,

Thanks for your advice.

I built my kernel with the mpls-linux patch, converted and installed the rpm
packages for iproute and quagga (during installation I have used libcrypto
and libsnmp in Debian). I executed the daemons using their absolute paths so
there should be no confusion. Actually, I can see from tcpdump that the
packets are really label switched.

The topology I am currently using for test does not have more two machines
connected to a single C.D, so the problem I have might be quite different to
yours. However, I have also noticed ldpd crashes, but they are much less
often compared to zebra crashes. Also, whenever I have a crash, I am able to
get a working system by killing the processes (zebra, ospfd, ldpd) and
launching them again.

2007/6/27, Julien Bisconti <julien.bisconti at student.fundp.ac.be>:
>
> Hi,
>
> Please, see my answer inline,
>
> On 6/27/07, Xu Yao < yaox06 at gmail.com> wrote:
> >
> > Hello,
> >
> > I am currently using netkit to emulate a lab about MPLS and LDP. I have
> > compiled a new kernel, updated the filesystem, installed an
> > MPLS-and-LDP-enabled quagga and executed some basic scenarios.
> >
>
> I think you are using mpls-linux and ldp-portable!  I did the same, I will
> explain few things that might have impact on your research. By the way, is
> the mpls4 module loaded? In other words, is your kernel MPLS enabled? Have
> you convert the rpm to deb or have you compiled everything from source code?
>
>
>
>  Everything worked fine until I tried to simulate a link/node down event.
> > I used the command "ifconfig ethx down" and I noticed that the zebra
> > process on some of the machines died silently without leaving any log
> > files.
> >
>
>
> I had the similar problem with ldpd (LDP daemon from quagga-mpls), it was
> when I configured (by vtysh) the daemon and the interface was connected to
> the same collision domain than two others machines. So, for one interface,
> ldpd has two next hop. This is explained by the fact that a collision domain
> is like a (virtual) hub, every packet sent to this c.d. will be received
> by every other machines connected to that c.d.
>
> The thing is sometimes it works, sometimes it doesn't (ldpd crashed) but
> when it crashed, I never managed to restart it. In other words, when I
> configured all the virtual machines in a specific order, I didn't have the
> same "result" (ldpd crashed or it doesn't). I didn't find out what was the
> exact cause but I think if the virtual hub were virtual switches, this
> problem would be solved. If your problem is coming from the Zebra daemon,
> make sure you have uninstalled the old zebra package. Like this you may
> avoid conflicts.
>
>
>  I would like to know if anyone has encoutered similar behavior before and
> > what can be done to prevent that from happening. Also, is there a better way
> > to simulate such an event on Netkit?
> >
>
> FYI, If you want to simulate a node down event, you'd rather use the
> vcrash command.
> If you want to simulate a link down event, I hope Massimo can help you out
> on this because I have no other idea than the "ifconfig ethX down" command.
>
>
>  Thanks.
> >
> > Yao
> >
>
> By the way, I think it may be a good idea to post this thread to the
> mpls-devel malling list.
> I hope it helps,
>
>
> Julien
>
>
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> >
> >
>
>
> --
> --------------------------------------------
> Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
> M.Sc. student in Computer Science, University of Namur
> FUNDP, Belgium
> _______________________________________________
> Netkit.users mailing list
> Netkit.users at list.dia.uniroma3.it
> http://list.dia.uniroma3.it/mailman/listinfo/netkit.users
>
>
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