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



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.

UMTS, 3G, mobile broadband are usually just selling names to GPRS, General
Packet Radio Service built upon existing GSM or newer UMTS/WCDMA
networks.

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. 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.

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. 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. Thus the phone
is the PPP endpoint. And thus all the different PPP implementations are
a bit funky.

Seek more info with the GPRS abbreviation.

-Mikko
.



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