Re: Re: how network-manager chose connection?

[Markus Becker <mab comnets uni-bremen de>]

> On Wed, 2010-07-07 at 14:26 +0200, Pierre-Marie Coron wrote:
> > Hello everybody,
> > 
[...]
> 
> At the moment the order can't be changed, it's a function of the
> "default route" that is set, either by NM or (if you don't use NM)
> normal system networking scripts.  It all depends on which connection is
> started, either  manually by you, or automatically by NM.
> 
> NM will autostart the last-used connection by default if it's wired or
> wifi.  When multiple connections are active, the ordering is wired >
> wifi > 3G.

Hi Dan,

some time back in the times of NetworkManager in SVN, we made some 
modifications to NetworkManagerPolicy, so that it exposes the priority of 
connections/devices/device types (don't remember which one) over DBUS, so that 
a user (program) could change the priority and initiate an update of the 
routing and DNS. Are you interested in applying that to git? If yes, then I 
would start digging it out.

> 
> > I want to make a proxy server who chose the connection according to
> > the aviability of it or the kind of protocol witch is using.
> > For exemple instant messaging don't need a big bandwidth but streaming
> > yes so  instant messaging could be used though 56k modem or GPRS key
> > instead of  using the ethernet connection.

This is similar to what we did. Applications could register with some service 
and based on the applications the service would set the priorities inside NM.

Markus

> This is somewhat complicated, because it's not about which connections
> are active and which aren't, but it's about IP routing which
> NetworkManager doesn't really get into (other than setting the default
> route).
> 
> You can *simulate* this by adding specific routes to the servers you
> want to use to the routing table.  So if you know your IM server's IP
> address you could:
> 
> ip route add <im server ip>/32 dev <gprs interface name>
> 
> If that IP address is stable, you can add it to the NetworkManager
> connection infromation for your GPRS connetion in the connection
> editor's IPv4 Routes dialog and all your IM should then go over GPRS.
> You can do that with NM today.
> 
> You can't use the kernels IP routing table for *classes* of traffic
> right now, but you might be able to use the Linux firewall (iptables) to
> do this for you since it's quite a flexible packet filter and does a lot
> more than just firewalling.
> 
> So the short answer is:
> 
> - yes, you can make traffic to specific IP address or subnets use a
> specific interface by adding those subnets as routes to the NM IPv4
> Routes dialog
> 
> - it's a lot more complicated to send classes of traffic (ie, all web
> traffic) out over a specific interface
> 
> Dan
> 
> > I already see documentation about QoS software like wondershaper but
> > it is made for one connection.
> > I hope my message is clear and i apologize for my poor English.
> > 
> > Best regards
> > 
> > PM
> > _______________________________________________
> > networkmanager-list mailing list
> > networkmanager-list gnome org
> > http://mail.gnome.org/mailman/listinfo/networkmanager-list
> 
> _______________________________________________
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------------------------------------------------
| Dipl.-Ing. Markus Becker
| Communication Networks
| Mobile Research Center
| TZI - Center for Computing Technologies
| University Bremen
| Germany
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| web: http://www.comnets.uni-bremen.de/~mab/
| mailto: mab comnets uni-bremen de
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