Re: [mpls-linux-general] Debian GNU/Linux MPLS installation problem

[James R. L. <jl...@mi...>]

Please see my recent post about debian packages.

On Sun, Jul 17, 2005 at 04:43:32PM +0300, Razvan Deaconescu wrote:
>        Hi everybody,
>=20
> we are trying to install MPLS support on some Linux machines and to get as
> many things working as we can; we began with configuring the kernel an te=
sting
> the mpls utility using the iproute2 application suite; we chose the Debian
> GNU/Linux distribution because we are quite accustomed to it and we can p=
roceed
> much faster with this project.
>=20
> However we ran into many problems some of which we were able to solve.
> I will make quite a detailed presentation of the things we did so far bec=
ause
> we don't want to miss anything important, in case anyone can help us.
>=20
> First of all, if anyone has managed to install a functional MPLS support =
on a
> Debian GNU/Linux distribution we kindly ask him/her to tell us the steps =
that
> he/she followed and where we went wrong.
>=20
> Ok, here it goes.
>=20
> We used Debian GNU/Linux 3.1 Sarge as our base system. We used the network
> install minimal CD available at
> http://cdimage.debian.org/debian-cd/3.1_r0a/i386/iso-cd/debian-31r0a-i386=
-netinst.iso
>=20
> After the installation, the first thing we had to do was compiling the ke=
rnel
> with MPLS support. We used the latest available patch mpls-linux-1.946a.
> We used (as a test) 4 different kernel versions, namely 2.6.9, 2.6.10,
> 2.6.11.12 and 2.6.12.2.
>=20
> This is where we ran into some of our problems: only the 2.6.9 version of=
 the
> kernel could be successfully patched; these are the links where you can f=
ind
> output for the patch applied to the 2.6.9, 2.6.10, 2.6.11.12 and 2.6.12.2=
 kernel
> versions.
>=20
> 2.6.9:          http://atlantis.cs.pub.ro/~razvand/output-2.6.9
> 2.6.10:         http://atlantis.cs.pub.ro/~razvand/output-2.6.10
> 2.6.11.12:      http://atlantis.cs.pub.ro/~razvand/output-2.6.11.12
> 2.6.12.2:       http://atlantis.cs.pub.ro/~razvand/output-2.6.12.2
>=20
>        Because we didn't want to loose to much time, we chose the 2.6.9
> kernel version. We did a
>        # make menuconfig
> and added all the options presented in the QUICK.START help file.
>=20
>        Afterwards, we compiled the kernel the Debian way (via make-dpkg)
> and created a debian package containing the compiled kernel image. We ins=
talled
> the image, restarted the machine and booted the new kernel. Everything we=
nt
> smoothly. The next step was testing our kernel for MPLS support.
>        By the way, we also tried compiling the 2.6.11.12 kernel (even tho=
ugh
> the patching failed). But, as we anticipated, the mpls files attached in =
the
> net/mpls directory were not compiled within the kernel (due to the fact t=
hat
> the Makefile in the net/ directory itself couldn't be patched).
>=20
>        Back to our 2.6.9 kernel, we browsed to the net/mpls/ directory
> and found that the mpls files were indeed compiled and thus inserted in t=
he
> new kernel. We were left with testing mpls support inside this new kernel.
> As the mplsadm utility is now obsolete, we decided to try the iproute2 wi=
th
> MPLS patching (in order to use the mpls command).
>=20
>        We used the RPM source package available at
>        http://sourceforge.net/projects/mpls-linux
>=20
>        Because Debian also has RPM support we could install the iproute2
> rpm source package; this contained iproute2-2.6.9 and also various patche=
s.
> We patched iproute2 (everything went fine).
>=20
>        But when we tried to compile it, a lot of compilation errors emerg=
ed.
> All of them were: "_SOME_KIND_OF_VARIABLE_OR_MACRO_ undeclared". We
> soon found that the header files mpls.h and gen_spec.h were not present
> in /usr/include/linux.
>        I don't know why this happened (or maybe this usually happens). So
> we copied both files from /usr/src/linux/include/linux to /usr/include/li=
nux.
> We also had to install the db library as our system lacked it.
> A simple command:
>        # apt-get install lidb4.2-dev
> solved that problem.
>=20
>        After that we managed to compile and install all the iproute2 util=
ities,
> including mpls.
>=20
>        What we had to do now was test the mpls utility. We used the examp=
le
> of James Leu located at http://mpls-linux.sourceforge.net/simple.php. We =
have
> four computers connected in a network, so there was no problem choosing t=
wo
> of them to test mpls.
>        The command for uml1 went fine. However the fifth one, namely:
>                # mpls nhlfe show
> lacked the "push gen 10000 set eth0 ipv4 xxx.xxx.xxx.xxx" part
> (obviously we were using the eth0 network interface and a private ip addr=
ess)
>        The next command:
>                # ip route show
>        clearly showed the new route being added (but we were left with the
> missing part from the previous command)
>=20
>        We moved to the second machine (this is where our problems increas=
e).
> The third command:
>                # mpls ilm add label gen 10000 labelspace 0
> give us "Segmentation fault"
>        the next time we try to run it it just blocks and does nothing. We
> were left with debugging these problems.
>=20
>        Although, somehow empirical, we used printing in order to get a gr=
ip
> of the code flow. Thus we managed to find out exactly where our problems =
take
> place.
>=20
>        I will show the sequence of function call that finally give us
> Segmentation fault, and then the sequence that give us the blocking comma=
nd.
>=20
>        We are referring to the iproute2-2.6.9 patched source code.
>=20
> segmentation fault:
>        mpls/mpls.c
>        int main (void) -> do_ilm -> mpls_ilm_modify -> rtnl_talk
>        (lib/libnetlink.c) -> status =3D send_msg (rtnl->fd, &msg, 0);
>                                this is the line where it cracks :-)
>=20
> blocking command:
>        mpls/mpls.c
>        int main (void) -> ll_init_map (&rth1) (lib/ll_map.c) ->
>        -> rtnl_dump_filter (lib/libnetlink.c) ->
>        -> status =3D recvmsg (rth->fd, &msg, 0);
>                this is the line where it blocks
>=20
> we am not sure if the failure of this command has anything to do with the
> failure of the command for uml1 (# mpls nhlfe show - which lacks part of =
the
> message)
>=20
> to make matter worse, we think the problem may affect the kernel; after t=
he
> segmentation fault message, any attempt to shut down or reboot the machine
> will end up in a block with the following message:
>        Deactivating swap ... umount: tmps busy
>        - remounted read-only
>        done.
>        unmounting local filesystems ... umount:
>        tmpfs busy - remounted read only
>        umount: /: device is busy
>        done.
>        mount: / is busy
>        Rebooting ...
>=20
>        right here it hangs (have to restart it manually)
>=20
>        Many other thing stop working actually, so the problem may
> affect the kernel
> a bit more.
>=20
>        We are sorry for the long message, but we wanted to show in detail
> everything we have done so that it may be easier for others to spot the p=
roblem
> and help us.
>=20
> Thank you very much,
> Razvan & Dorin
>=20
>=20
> -------------------------------------------------------
> SF.Net email is sponsored by: Discover Easy Linux Migration Strategies
> from IBM. Find simple to follow Roadmaps, straightforward articles,
> informative Webcasts and more! Get everything you need to get up to
> speed, fast. http://ads.osdn.com/?ad_idt77&alloc_id=16492&op?k
> _______________________________________________
> mpls-linux-general mailing list
> mpl...@li...
> https://lists.sourceforge.net/lists/listinfo/mpls-linux-general

--=20
James R. Leu
jl...@mi...