Re: FC8

[Dan Williams <dcbw redhat com>]

On Mon, 2008-04-28 at 10:38 +0200, Stefan Seyfried wrote:
> Dan Williams wrote:
> > On Sat, 2008-04-26 at 09:49 +0100, Luke Sheldrick wrote:
> 
> >> Anyways it has detected my inbuilt 3g modem in my Dell D420, and amazingly just connected... without the need to enter the APN or anything else?
> 
> Yes, that's really scary, since you are not knowing which provider it is going
> to use. Well, you'll know once you get the bill ;-)
> 
> The card normally just uses the APN that's already stored in the SIM profile.
> 
> But what i'd like to know: how did you enter the PIN for your SIM card? I was
> not able to connect until i entered the PIN first with umtsmon or comgt.
> 
> > I don't believe you need the APN except in certain circumstances like
> > roaming or other less-common configurations.  We've got somebody working
> > on a mobile wizard that should be able to select the right APN for you
> > though if you need it.
> 
> Different APNs often mean different billing schemes - for my no-limit flat
> data plan i need a different APN than for the normal, data volume charged data
> plans. Guess what APN was stored in the SIM when i got it...
> 
> >> Was just wondering if it should show the network name, i.e. T-Mobile? and is there a way to get it to show the signal strength?
> > 
> > Yeah, both of these would be nice things to have.  Unfortunately, some
> > of that is blocked on the card vendors themselves becoming a bit more
> > open.  Most cards do not allow you to retrieve information about the
> > connection while you're connected, unless you use a proprietary protocol
> > that you must license from the vendor.
> 
> Please quantify "most cards". From the ~10 cards i have, only one, the Novatel
> X870 which only has one usable port, has this problem (but you can still
> select the provider and check signal strength before connecting).
> All other cards (Option, Sierra Wireless, Huawei) have two usable ports and
> you can use one of them to query for network data while being connected.

Yes, you can do this on some cards.  I've never said this was impossible
for all cards.  I just said it was impossible for huge numbers of common
cards, many of which are CDMA, and many of which are GSM.

The two Novatel cards I've used do not allow this (MC727, S620), none of
the Sierra cards I have that have > 1 serial port do this (AC595U,
AC580), the Kyocera card I've used (KPC680) does not, and the Pantech
card (PC5750) doesn't either.  I don't know whether the AC860 I have
does, because it only exposes one serial port and therefore would need a
multiplexer I guess.

In addition, Sierra states here:

http://www.sierrawireless.com/faq/ShowFAQ.aspx?ID=1119

"If you are using the AC875, MC8775, or later MiniCards, issue AT
commands or queries to /dev/ttyUSB0. AT commands can be used while a
data connection is established on /dev/ttyUSB2.

All other GSM devices should issue AT commands/queries to /dev/ttyUSB0.
However if a ppp connection is established on that port, AT commands
cannot be used."

Novatel states here (for the XU870 HSDPA card):

http://www.novatelwireless.com/support/merlin-xu870-linux.html

"Known Limitations
      * You cannot monitor card status such as signal strength, bytes
        exchanged, or connectivity status. The only network indication
        available is the wireless card LED that indicates if the card is
        in a coverage area. 
"

In fact, I have not actually encountered a USB-based card that _does_
let me talk to it with minicom on ttyUSB1 or ttyUSB2 while it's
connected.  I know they are out there, they just aren't common in the
Americas, whether they are GSM or CDMA doesn't make a difference.

> This is also working for a long time in UMTSmon and Klaas would probably be
> happy to answer questions about the cards and provide contacts into the
> industry, if needed.

I've also talked to people at Sierra and Novatel.  They also state that
most of their cards use proprietary protocols on the secondary and
tertiary ports.  I've heard that Option uses AT commands instead, which
is nice.

> >  We're trying to pry some bits of
> > those open, but it may take a while.  There are a couple avenues though.
> 
> I think that by just using the bits that are readily available, a much better
> user experience would be possible today.

My point is that lots of people have cards that don't allow this
functionality under Linux yet.  If most cards used AT commands, I'd add
support tomorrow.  That would be awesome.  But since a huge number
don't, we need to understand the entire field; what cards do?  how do
they support it?  what cards don't?  how can we easily identify cards
that do and cards that do not?  If a card does, are there variations in
the commands and responses?

The way this support gets into NetworkManager is going to be the
following:

1) Add a property in HAL to tag the secondary port that can be used for
communication, if it exists

2) Tag secondary ports of cards known to support AT commands with the
correct modem.command_sets properties, and then add the property from
(1) so we know they are a secondary port 

3) Recognize secondary ports in NM, and for those cards that support
them, provide signal strength and connection speed status to the user

Dan