Mikko Rapeli <(E-Mail Removed)> schrieb:
> On 2009-01-20, Nico Schottelius <(E-Mail Removed)> wrote:
>> Does anyone else have a clue about this and can point me to some
>> documentation providing more in detail about that issue?
>
> If you have an account, www.3gpp.org has the specs including a nice one
> about the network architecture.
Don't have an account over there, but will dig into the public things.
> UMTS, 3G, mobile broadband are usually just selling names to GPRS, General
> Packet Radio Service built upon existing GSM or newer UMTS/WCDMA
> networks.
Yep, that's "a bit" clear over here, as those "lines" simply
implement network layer 1 for me.
> A GPRS phone/modem sends user data as IP packets over GSM, EDGE, WCDMA,
> HDSPA etc wireless link to the operators base stations which route the data
> to
> SGSN and GGSN routers and eventually to the Internet.
That's interesting! Weeks ago I was convinced that the ppp-packets are
travelling over the link.
> Though, I think
> the specs mention an option of using PPP too, but that requires more
> work from the PPP endpoint in the network. If you know about the AT+CGDCONT
> command which sets the Packet Data Protocol context, the IP in it stands
> for the Internet Protocol.
Interesting, I'm wondering what else may follow with CGDCONT?
> Now when a computer is attached with a RS-232, IRCOMM, Bluetooth RFCOMM,
> USB or similar serial connection to the mobile phone, or plain modem,
> the chosen protocol is most often PPP.
Yep, slip is (almost) dead.
> I'm not sure if it's actually
> mandatory to implement, but that was how analog modems connected
> computers to the Internet in the old days. Only quirck is that with
> GPRS, the phone transmits IP to the network so it relays the IP packets
> between the PPP link and the actual GPRS radio protocol.
Do you have any clue, how the provider relays dns information to the modem?
I mean, with plain IP there's no way to submit it.
Did they implement something like DHCP? My guess would be yes, as the modem
also retrieves wins and ip address information (somehow).
> Thus the phone
> is the PPP endpoint. And thus all the different PPP implementations are
> a bit funky.
That explains quite much, also related to the other post, that most
chips are indeed made by qualcomm.
> Seek more info with the GPRS abbreviation.
Thanks, will do!
Sincerly,
Nico
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