wireshark, viewing Abis communication

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Harald Welte laforge at gnumonks.org
Thu Jul 30 21:03:05 UTC 2009


On Thu, Jul 30, 2009 at 01:00:46PM +0200, Nordin wrote:
> Hi,
> 
> according to the wiki for the nanobts:
> 
>    * 0x00 RSL messages as per GSM 08.58
>    * 0xfe ip.access specific messages
>    * 0xff OML messages as per GSM 12.21
> 
> I assume this is the so called SAPI?

no. SAPI only exists in E1 based A-bis.

> Cause I read some Abis articles that for RSL and OML is resp. 0 and 62.
> I just want to be sure there are some value differences.

A-bis over E1 is what the BS-11 uses.  ip.access has their own proprietary
protocol stacking and A-bis dialect.  There is no public documentation about
it, apart from what we deducted from protocol traces and implemented in OpenBSC
/ wireshark and put into the OpenBSC wiki.

In any case, the Layer 2 (Q.921 on E1, with TEI and SAPI) is completely 
uninteresting.  All you should care about is layer 3 (12.21 OML and 08.58 RSL).

Whatever is below is the transport layer and does not actually have any actual impact on the GSM netwokr

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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