Re: Why do UMTS-links provide DNS Server 10.11.12.13 and 10.11.12.14?



Mikko Rapeli <foo@xxxxxxxxxxx> schrieb:
On 2009-01-20, Nico Schottelius <nico@xxxxxxxxxxx> 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

--
Think about Free and Open Source Software (FOSS).
http://nico.schottelius.org/documentations/foss/the-term-foss/

PGP: BFE4 C736 ABE5 406F 8F42 F7CF B8BE F92A 9885 188C
.



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