Re: Multi Active Devices

["Tambet Ingo" <tambet gmail com>]

On Sat, Dec 20, 2008 at 16:32, Etienne Zind <etienne zind gmail com> wrote:
> I'm using the NetworkManager shipped in the last Ubuntu distro (0.7). I've been
> able to connect few devices in the same time as expected (eth0, ppp0, wan0). As
> expected too, although all three ISPs are connected only one (eth0) is actually
> used (default route). The way NM updates the route table prevents any packet to
> be routed by another device than the default one even if specified on software:
>
> $ wget --bind-address=$IP_WAN0 http://foo.bar/index.html # fails
> $ wget --bind-address=$IP_PPP0 http://foo.bar/index.html # fails
> $ wget --bind-address=$IP_ETH0 http://foo.bar/index.html # OK
>
> So I had a look at the "Linux Advanced Routing & Traffic Control HOWTO" by
> Bert Hubert [1] and implemeted the setup [2] described in the "Routing for
> multiple uplinks/providers" and it did work perfectly (even with a trivial load
> balancing over the 3 ISPs with the multipath default route).

I seriously doubt people want load balancing in general (for example,
in case of active ethernet and modem devices). There are many
possibilities for setting up routing in case of multiple active
devices (like split access, load balancing, failsafe/backup, ...) and
we have no way of configuring that with NM right now. We have data
structures for connections (one per active device), but we don't have
defined relations between them.

> The basic idea is to use many routing tables together, and some rules to define
> which table to use. I implemented it in a perl script that I execute manualy
> everytime  something change in the NM environement (how to do that
> automaticaly ?)

Whenever a device is activated/deactivated, the dispatcher scripts are
called from /etc/NetworkManager/dispatcher.d/ directory, so you should
put your script there and test how your script is called. The first
argument passed to the scripts is the device interface name, the
second is "up" or "down".

> I would love to get my fingers dirty in your elegantr GObj C code, although I
> might need some "emlightment" from you guys to be sure it worth it.
> Please have a look at my shell script (working). Any comment will be
> welcome.

I couldn't see it, it kept timing out for me, but it would be a good
start to convert it to C and use libnl so that it would be easy to add
to NM when it's ready.

Tambet

>
> [1] http://lartc.org/howto/index.html
> [2] http://parad0x.org/~barbu/dev/mad/mad-setup.pl
>
> --
> Regards,
> Etienne Zind
>
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