Re: [mpls-linux-devel] Development LDP/MPLS

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

Hello Julien,

My comments are inline ...

On Wed, Jan 10, 2007 at 04:59:31PM +0100, Julien Bisconti wrote:
> Hello James,
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> Please, see my answer below.
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> On 12/12/06, James R. Leu <jl...@mi...> wrote:
> >
> >Excellent to here from you.  I'm glad you've made it this far.  Now
> >lets dig in and start to understand what already exists.
> >
> >First let me start by explaining that ldp-portable is just a library.
> >It relies upon something called a "porting layer" to provide the low
> >level primitive and infrastructure to build a working implementation
> >of LDP (or CR-LDP in your case).  Here is a diagram of the layers involv=
ed
> >and the types of things handled in that layer:
> >
> >---------------------------------
> >  user interface
> >  - protocol configuration
> >  - maintain configuration state
> >  - status queries
> >  - error notification
> >---------------------------------
> >  ldp-portable
> >  - packet encode/decode
> >  - message processing
> >---------------------------------
> >  porting layer
> >  - socket activity: read/write, multicast
> >  - timers
> >  - memory allocation
> >  - routing interaction
> >  - interface interaction
> >---------------------------------
> >
> >The API that needs to be filled in by the porting layer is defined in
> >ldp-portable/common/*_impl.h
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> I don't really understand what is needed to be filled in. The files impl_=
*.c
> seem to fill the API completely. Could you explain me what is needed to be
> filled in,

If someone were trying to port ldp-portable to another
routing system (XORP for example) these files would need to be
re-implemented.  I've already done the "heavy lifting" of porting
ldp-portable to quagga.  I was pointing out these files
merely to give you an overview of how ldp-portable relates
to quagga.

> ldp-portable provides an API to the user interface (and the porting
> >layer for some OS driven actions), which is defined in
> >ldp-portable/ldp/ldp_cfg.c. This is called the configuration API.
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> OK.
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> quagga-mpls is a just one porting layer that exists (by far the most
> >mature).  So that is our next step, lets look at how quagga-mpls interac=
ts
> >with the configuration API defined in ldp_cfg.c.
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> I read the Zebra Hacking Howto to understand how an implementation of a
> protocol works. Now, I understand how to interact with a protocol by the
> VTY.

Great.  Understanding the quagga vty is very important.

> Most of the actual user interface for quagga's usage of ldp-portable
> >is defined in quagga-mpls/ldpd/ldp_vty.c.  It relies upon the utilities
> >and structure implemented in ldp_interface.c, ldp.c and ldp_remote_peer.c
> >to maintain the configuration state for ldpd.  It makes calls to the
> >configuration API to actually make ldp-portable do something.  In
> >addition,
> >the code in ldp_zebra.c is responsible to feeding routing and interface
> >changes into ldp-portable.
> >
> >So for your first task, you'll need to figure out how you want the
> >user to configure CR-LDP.  Most of the work is done.  The user can alrea=
dy
> >configure LDP at the global and interface level, all that is needed is
> >a way to tell ldp-portable that we want to create a "tunnel" and configu=
re
> >the details of the tunnel, like where it should terminate, and what
> >path to take to get there.  There already exists the configuration
> >API for these components, but it is untested, and doesn't really
> >do anything.  So that is what the 2nd (3rd, 4th, 5th ..... :-) step will
> >be.
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> I think my first task is done. I figured out how the user can configure
> CR-LDP. I looked at the code, I saw that Nortel also wrote two files
> (ldp_nortel.[ch]) with a lot of accurate information in it concerning the
> CR-LDP protocol. I noticed that in the configuration API, the functions to
> create a "tunnel" already exist :

Good.  As you can see all of the necessary encodes/decodes for
CR related TLVs exist.  At the simplest level all you need to
do is figure out how to trigger these encodes and decodes :-)
Take a look at ldp_buf.c (ldp_encode_one_mesg) to understand
how ldp-portable utilizes ldp_nortel.c

> extern mpls_return_enum ldp_cfg_tunnel_set(mpls_cfg_handle handle,
> ldp_tunnel * r, uint32_t flag);
> extern mpls_return_enum ldp_cfg_tunnel_test(mpls_cfg_handle handle,
> ldp_tunnel * r, uint32_t flag);
> extern mpls_return_enum ldp_cfg_tunnel_get(mpls_cfg_handle handle,
> ldp_tunnel * r, uint32_t flag);
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> The files ldp_tunnel.[ch] contain few functions to deal with tunnels. So,
> now what you want me to do?

The API in ldp_cfg tries to mimic the LDP-MIB and the TE-MIB.
I believe I've implemented trivial code for creating all of
the structures laid forth in the TE-MIB.  So your task is to
create the quagga vty interface that creates the structures
in the TE-MIB and then fiddles the correct bits in the
ldp_mesg data that is being sent to ldp_encode_one_mesg.
Of course there will be additional work involved in
processing packets you receive with the CR TLVs, but
we'll worry about that after you can send packets with CR TLVs :-)

> I know this was a lot to digest, look at the code, ask questions and
> >hopefully we'll get you writting code shortly.
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> I hope so!
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> Again, thanks for your interest, I'm really happy that you're willing
> >to contribute and work on this aspect of mpls-linux.
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> My pleasure !
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> I hope to hear from you soon.
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> I'm sorry not to reply sooner but with the holidays and complexity of the
> project, sometimes I got lost into the code.
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> Thank you for your help
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> Julien
>=20
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> On Mon, Dec 11, 2006 at 04:10:54PM +0100, Julien Bisconti wrote:
> >> Hello Sir,
> >>
> >> This email is to let you know that I can compile everything on the
> >> repository. So I am available to help you. I keep digging into
> >quagga-mpls
> >> now that I finally managed to install it.
> >>
> >> I hope to hear from you.
> >>
> >> Regards,
> >>
> >> Julien
> >>
> >> On 12/4/06, Julien Bisconti <jul...@gm...> wrote:
> >> >
> >> > Hello Sir,
> >> >
> >> >James R. Leu wrote:
> >> >
> >> >Hello Julien,
> >> >
> >> >Would you mind if we moved this discussion to the mpls-linux-genernal
> >> >mailing list?
> >> >
> >> > I just solved the problem of the gnu autotool (Murphy's law) so I
> >don't
> >> >think that moving this discussion will be necessary. But if you want =
to
> >> >move
> >> >the _whole_ discussion concerning the development of dynamic LSPs then
> >I
> >> >fully agree with you.
> >> >
> >> >Thank you again for the help.
> >> >
> >> >Here are the versions of auto tools I use on my development machine:
> >> >
> >> >    autorun-3.18-1.2
> >> >    automake-1.9.6-2
> >> >    autoconf-2.59-7
> >> >
> >> >In addition I do not believe you should be using 'update-autotools'
> >> >Instead you should just issue a:
> >> >
> >> >    ./cleanup-jleu
> >> >    autoreconf
> >> >    ./configure
> >> >
> >> >from the quagga-mpls directory.
> >> >
> >> >On Mon, Dec 04, 2006 at 03:14:40PM +0100, Julien Bisconti wrote:
> >> >
> >> > Sir,
> >> >
> >> >As asked, I compiled every program on the repository except quagga-mp=
ls
> >> >(the
> >> >one I think I really need)
> >> >The problem is I can't even try to compile, I never managed to get to
> >> >configure script with the gnu autotool.
> >> >
> >> >I googled the whole weekend to find out what is the error, apparently
> >it
> >> >seems to be a problem with the macro of aclocal. I re-pulled the code
> >of
> >> >quagga-mpls from perforce specifying that I want to keep the
> >modification
> >> >time of the original file, no way to get the configure script.
> >> >
> >> >Here is the error I get from autoreconf, from "aclocal -I m4" or from
> >the
> >> >update-autotools script)
> >> >
> >> >/usr/bin/m4:configure.ac:1416: ERROR: recursion limit of 1024 exceede=
d,
> >use
> >> >-L<N> to change it
> >> >autom4te-2.60: /usr/bin/m4 failed with exit status: 1
> >> >aclocal-1.9: autom4te failed with exit status: 1
> >> >autoreconf-2.60: aclocal failed with exit status: 1
> >> >
> >> >I'm really stuck at this point. Everything else is allright. I tried =
to
> >> >compile the original version of quagga-0.99.5 (downloaded from the ma=
in
> >web
> >> >site) and I have the *same error*. I'm currently using Gentoo 2006.1a=
nd
> >> >here is the version of gnu autotool I use :
> >> >
> >> >autoheader (GNU Autoconf) 2.60
> >> >autoconf (GNU Autoconf) 2.60
> >> >ltmain.sh (GNU libtool) 1.5.22 (1.1220.2.365 2005/12/18 22:14:06)
> >> >libtoolize (GNU libtool) 1.5.22
> >> >aclocal (GNU automake) 1.9.6
> >> >automake (GNU automake) 1.9.6
> >> >
> >> >I would really appreciate your help on this because no one else seems
> >to
> >> >have the same problem as I do.
> >> >
> >> >Thank you in advance.
> >> >
> >> >Julien
> >> >
> >> >On 12/1/06, James R. Leu <jl...@mi...> <jl...@mi...>
> >wrote:
> >> >
> >> > Hello,
> >> >
> >> >I'm glad to here your interested in helping with mpls-linux.
> >> >The best way to get involved is to pull the code from my
> >> >development tree via P4.  Once you have that, make sure you know
> >> >how to build and install the software from the trees.  Once you have
> >that
> >> >figured out, then we can start looking at the code and figuring out
> >were
> >> >you need to make changes.
> >> >
> >> >I use Fedora 5 as my development plateform.  Other then that I use go=
od
> >> >ol'
> >> >vi and gcc.  For testing I use xen instances networked together via
> >bridge
> >> >interfaces.
> >> >
> >> >Let me know how you're progressing on pulling the code from P4 and
> >> >building
> >> >and installing the programs.
> >> >
> >> >On Tue, Nov 28, 2006 at 03:08:37PM +0100, Julien Bisconti wrote:
> >> >
> >> > Sir,
> >> >
> >> >My name is Julien Bisconti, I am currently a student in computer
> >science
> >> >
> >> > and
> >> >
> >> > I aim to test the dynamic configuration of LSP on a testbed.
> >> >
> >> >It is said in ldp-portable FAQ that it not implemented yet but
> >> >
> >> > everything is
> >> >
> >> > ready for it.Maybe I can help you with that.
> >> >Could you give a hint by telling me how (where in the code) can I
> >> >
> >> > implement
> >> >
> >> > CR-LDP? The development guide doesn't speak about LDP.
> >> >
> >> >By the way, I managed to install LDP (quagga/ldp-portable) and MPLS
> >> >
> >> > (kernel
> >> >
> >> > + iptables/iproute/ebtables) and I would like to know which software
> >do
> >> >
> >> > you
> >> >
> >> > use to develop those, in case I would code something. Because they a=
re
> >a
> >> >
> >> > lot
> >> >
> >> > of files and I'm not used to it.
> >> >
> >> >I hope to ear from you soon.
> >> >
> >> >Regards,
> >> >
> >> >Julien Bisconti
> >> >
> >> >PS: I also sent a mail to the mailing list on SourceForge
> >> >
> >> >
> >> >--
> >> >--------------------------------------------
> >> >Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
> >> >M.Sc. student in Computer Science, University of Namur
> >> >FUNDP, Belgium
> >> >Traineeship: UPC (Barcelona, Spain)
> >> >
> >> > --
> >> >James R. Leu
> >> >jl...@mi...
> >> >
> >> >
> >> >
> >> >       --
> >> >--------------------------------------------
> >> >Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
> >> >M.Sc. student in Computer Science, University of Namur
> >> >FUNDP, Belgium
> >> >Traineeship: UPC (Barcelona, Spain)
> >> >GSM BELGIQUE: +32 474 598 418
> >> >GSM ESPA?A: +34 671 168 458
> >> >
> >> >
> >> >--
> >> >--------------------------------------------
> >> >Julien BISCONTI <jul...@st...>
> >> ><jul...@st...>M.Sc. student in Computer Scienc=
e,
> >> >University of Namur
> >> >FUNDP, Belgium
> >> >GSM BELGIQUE: +32 474 598 418
> >> >GSM ESPA?A: +34 671 168 458
> >> >
> >> >
> >>
> >>
> >> --
> >> --------------------------------------------
> >> Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
> >> M.Sc. student in Computer Science, University of Namur
> >> FUNDP, Belgium
> >> Traineeship: UPC (Barcelona, Spain)
> >> GSM BELGIQUE: +32 474 598 418
> >> GSM ESPA?A: +34 671 168 458
> >
> >--
> >James R. Leu
> >jl...@mi...
> >
> >
> >
>=20
>=20
> --=20
> --------------------------------------------
> Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
> M.Sc. student in Computer Science, University of Namur
> FUNDP, Belgium
> Traineeship: UPC (Barcelona, Spain)

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