Re: R13 S1AP message "Reroute NAS Request" is not decoding completely using 2.3.0

[Pascal Quantin <pascal.quantin () gmail com>]

Hi Sabyasachi,

2017-04-17 12:03 GMT+02:00 Sabyasachi Samal <sabyasachisamal () gmail com>:

> Dear Pascal,
> It decodes upto S1-Message using the fix. But the mandatory parameter "MME
> Group ID" is not decoded. Please have a look.
> [image: Inline image 1]
This is because of a PER encoding error. The RerouteNASRequest IE indicates
only 3 sub IEs instead of 4 (value 0x03 at offset 6 since the beginning of
the S1AP message). If you replace it with 4 (as seen in the attached pcap),
you get the MME Group IE.
So it must be fixed on your side.

Best regards,
Pascal.


> Regards,
> Sabyasachi
>
> On Fri, Mar 17, 2017 at 10:46 PM, Pascal Quantin <pascal.quantin () gmail com
> > wrote:
>
> > 2017-03-17 17:48 GMT+01:00 Pascal Quantin <pascal.quantin () gmail com>:
> >
> > > Hi Sabyasachi,
> > >
> > > 2017-03-17 17:36 GMT+01:00 Sabyasachi Samal <sabyasachisamal () gmail com>:
> > >
> > > > Hi Anders,
> > > > Thanks for the response. I am using the message structure of TS 36.413
> > > > v13.3.0 and wireshark development version Version 2.3.0-2658-gfe285c6
> > > > (v2.3.0rc0-2658-gfe285c6). I do not know the process of filling a ticket
> > > > for wireshark. Attaching the trace here so that you guys can help.[image:
> > > > Inline image 1]
> > > Wireshark tries to decode the S1-Message element as a UE Initial Message
> > > PDU, and not as a S1AP message PDU. It means that the decoding is shifted
> > > by a few bits, leading to a wrong decoding. I'm gonna fix this.
> >
> > Fix under review here: https://code.wireshark.org/review/#/c/20595/
> >
> > Regards,
> > Pascal.
> >
> >
> > > > On Thu, Mar 16, 2017 at 2:49 PM, Anders Broman <
> > > > anders.broman () ericsson com> wrote:
> > > >
> > > > > Hi,
> > > > >
> > > > > The S1AP dissector in trunk is based on TS 36.413 V13.5.0 (2016-12)
> > > > > so I guess it should decode the message.
> > > > >
> > > > > The best is to raise a bug attaching a trace with the RerouteNASRequest
> > > > > message and describe what is not dissected correctly.
> > > > >
> > > > > Regards
> > > > >
> > > > > Anders
> > > > >
> > > > >
> > > > >
> > > > > *From:* wireshark-users-bounces () wireshark org [mailto:
> > > > > wireshark-users-bounces () wireshark org] *On Behalf Of *Sabyasachi Samal
> > > > > *Sent:* den 16 mars 2017 10:11
> > > > > *To:* Community support list for Wireshark <
> > > > > wireshark-users () wireshark org>
> > > > > *Subject:* [Wireshark-users] R13 S1AP message "Reroute NAS Request"
> > > > > is not decoding completely using 2.3.0
> > > > >
> > > > >
> > > > >
> > > > > Hi,
> > > > >
> > > > > R13 baseline S1AP message "RerouteNASRequest" is not decoding
> > > > > completely using 2.3.0. Can anyone suggest how to proceed on this or is
> > > > > there any plan supporting this.
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > >
> > > > > Regards,
> > > > > Sabyasachi
> > > > >
> > > > > ____________________________________________________________
> > > > > _______________
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> > > >
> > > >
> > > > --
> > > > Regards,
> > > > Sabyasachi
> > > >
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> --
> Regards,
> Sabyasachi
>
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Attachment: NAS_Reroute_Message_fixed.pcap
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