Wireshark · Ethereal-dev: Re: [Ethereal-dev] Change how SCCP determines ANSI/ITU variant

[Jeff Morriss <morriss@xxxxxxxxx>]

Guy Harris wrote:

> On Jan 7, 2004, at 2:45 PM, Michael Lum wrote:
>
> > I have ANSI MTP3/ANSI SCCP on one SS7 link for the A-interface
> > (Base Station Controller to Mobile Switching Center) and
> > ITU MTP3/ITU SCCP/ANSI TCAP on another SS7 link for the ANSI MAP 
> > interface
> > (MSC to whatever, MC/HLR, etc.).
> >
> > Currently the SCCP dissector uses the extern 'mtp3_standard' provided by
> > the MTP3 dissector.  Obviously this causes a problem with the 
> > configuration
> > above.
>
>
> Because both links are in one capture?  (If they're in separate 
> captures, you'd change the setting before or after reading in a file.)
>
> If so, then you'd need some way of making that a per-link property, 
> which would need
>
>     1) a mechanism for setting non-global properties through the UI, if 
> it can't be determined from the traffic;
>
>     2) a mechanism for specifying the link.

I suppose it *might* be possible for the SS7 dissectors to determine the 
standard heuristically (on a message by message basis)?  Sounds painful 
to me, but it might work.

Of course, we could get then into issues like "what if MTP3 determines 
the standard is ITU but SCCP determines the standard should be ANSI"?  I 
guess a global "I already decided the standard" flag could be used to 
clear that problem (while allowing the lowest-level protocol to be MTP3 
or M3UA or SCCP or...).