The A-interface specs, both GSM and ANSI (3GPP2), indicate which way
SCCP messages go and what subset of SCCP can be used.
I haven't looked at the GSM specs for a while but ANSI-A (3GPP2 IOS)
indicates which messages can be carried on which SCCP messages and
which entity will generate connection requests but some messages
are bi-directional.
For example, the ADDS Deliver message is used in both directions
for carrying SMS, OTA (IS-683), etc.
IS-683 doesn't have anything to indicate the direction.
Anders Broman has added 'link_dir' to solve this.
Thanks for the help.
--
Michael Lum Principal Software Engineer
4600 Jacombs Road +1.604.276.0055
Richmond, B.C.
Canada V6V 3B1
Star Solutions
> -----Original Message-----
> From: wireshark-dev-bounces@xxxxxxxxxxxxx
> [mailto:wireshark-dev-bounces@xxxxxxxxxxxxx] On Behalf Of Guy Harris
> Sent: June 21, 2009 10:16 AM
> To: Developer support list for Wireshark
> Subject: Re: [Wireshark-dev] Meaning of packet_info.p2p_dir ?
>
>
> On Jun 19, 2009, at 5:29 PM, Michael Lum wrote:
>
> > I was thinking mainly in terms of SCCP.
> >
> > There are protocols on top of SCCP where the receiver/sender is
> > important.
> >
> > Currently the SCCP code is setting the direction to SENT for which
> > ever point code originates the SCCP Connection Request.
> > Which is logical if you are trying to indicate who initated the
> > connection but it is not helpful for some of the protocols on top.
>
> Then perhaps there need to be separate direction indications
> - and perhaps some of them should use the pinfo->private_data pointer.
>
> > For example:
> >
> > OTA (IS-638)
> > ANSI-A (IOS)
> > SCCP
> >
> > The two entities involved, from the SCCP standpoint, are
> the BSC and
> > an MSC.
>
> Q.711 speaks of "peer-to-peer communication", and doesn't
> seem to indicate that SCCP has any notion of particular roles
> for the endpoints (just as neither TCP nor UDP do), so
> presumably there's nothing inherent to SCCP to indicate which
> endpoint is which.
>
> Is there anything in the A interface to indicate that? I
> presume there's nothing in IS-638 to indicate that.
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