Hi,
Looking at http://en.wikipedia.org/wiki/GSM and the network diagram I would
assume the you are tracing on the Air interface(Um)
I doubt that the various dissectors for GSM protocols in Ethereal can decode
that straight off ( e.g just feed the data to a dissector by
adding a pseudo header). A GSM MAP trace would be no help to you as it
covers the protocol used between MSC and HLR(I think) some
has been sent to the list though if you want to search for them.
Which GSM/3GPP spec covers layer 2?
Brg
Anders
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Från: ethereal-dev-bounces@xxxxxxxxxxxx
[mailto:ethereal-dev-bounces@xxxxxxxxxxxx] För Francisco.Cotrina@xxxxxx
Skickat: den 3 augusti 2005 13:46
Till: ethereal-dev@xxxxxxxxxxxx
Ämne: [Ethereal-dev] sample file for GSM frames
Hi
I am trying to analyse some GSM layer-2 frames that I extracted from my
mobile phone.
The problem is that they don't have the right header.
If I understand correctly, Ethereal needs the frame to be inside TCP-IP
encapsulation, probably also inside something called MCU2 or similar.
But this doesn't apply to GSM, so I would need someone to embed my GSM
inside a frame that Ethereal can understand.
I suppose the developpers for the gsm_map dissector have such examples, so
if you can send me an example file, it will be perfect for me.
Thanks
Francisco
for example, this is one of my frames:
25 06 21 00 05 f4 64 11 77 9e 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
25 001001-- Pseudo length : 9
------01 Flag
06 0------- direction from : originating site
-000---- TransactionID : 0
----0110 Protocol Discrim. : radio resource management messages
21 00100001 MESSAGE TYPE : PAGING REQUEST TYPE 1
00 ----00-- spare bits : 0
------00 Page Mode : Normal paging
--00---- Channel Needed : (first) Any Channel
00------ Channel Needed : (second) Any Channel
: Mobile Identity 1
05 00000101 length of Mob.ident.: 5
f4 1111---- Identity Digit 1 : hex value = f, if TMSI/P-TMSI
----0--- No. of ID digits : even
-----100 Type of identity : TMSI/P-TMSI
64 01100100 Identity Digit 2,3 : take hex value
11 00010001 Identity Digit 4,5 : take hex value
77 01110111 Identity Digit 6,7 : take hex value
9e 10011110 Identity Digit 8,9 : take hex value
