HAL and PPP interfaces

Dan Williams dcbw at redhat.com
Wed Dec 8 10:08:32 PST 2004

On Wed, 2004-12-08 at 12:50 -0500, Joe Shaw wrote:
> On Wed, 2004-12-08 at 18:56 +0300, Andrei Yurkevich wrote:
> > Is it possible to know about appearance/removal of PPP interfaces with 
> > HAL? Since hotplug notifies about these interfaces being brought 
> > up/down, HAL could listen to that and provide the information about 
> > them. If that is not implemented (yet), would anybody be interested if I 
> > try to add support for monitoring PPP interfaces with HAL?
> I haven't used PPP in a while, so I'm not sure how it works at the
> system level, but I think it makes a lot of sense to merge these
> properties onto the modem device, similar to how the normal ethernet and
> wireless properties are merged onto the network card device.

Same here, but could you explain a bit how the PPP stuff works Andrei?

For example, you have a PPP interface, but that traffic has to get moved
over some physical interface like your modem.  How do you tell the PPP
interface that its supposed to send traffic over a particular modem
device?  What does the routing table look like when the PPP interface is

Since modems would most likely show up as serial devices, (right?) of
course they won't show in ifconfig, but I assume that the PPP interface
does.  HAL, however, should only really show _hardware_ network devices
(since its a Hardware Abstraction Layer), and in this Joe's idea of
merging the PPP properties to the modem device makes sense.  We
shouldn't be having the PPP devices be top-level, since they really
aren't hardware.  Remember that we _don't_ add tun0/cipsec0 IPSEC
network interfaces into HAL even though they show up in ifconfig too.
They simply aren't hardware.

So, if we have stuff like an IP address for the PPP connection, we
should probably define some property hierarchy for modems and other
devices over which PPP can run, like:

Modem 1:
info.bus	serial
net.interface	/dev/ttyS0
net.ppp.interface	/dev/ppp0
net.ppp.link	1

We already break down network connection stuff by type, so we have for
example "net.80211.mac_address" and "net.80203.link", so I think it
would be acceptable to have "net.ppp.link" or whatever.


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