Ask Your Question

Revision history [back]

click to hide/show revision 1
initial version

5G MM Registration Accept decoding lacks some fields


Wireshark decoding on 5G MM OTA meesage, REGISTRATION_ACCEPT, lacks some fields.

The decoding result:

    Plain NAS 5GS Message
        5GS network feature support
            **gsm_a.len: 2**
            nas_5gs.nw_feat_sup.mpsi: 0
            nas_5gs.nw_feat_sup.iwk_n26: 0
            nas_5gs.nw_feat_sup.emf: 0
            nas_5gs.nw_feat_sup.emc: 0
            nas_5gs.nw_feat_sup.vops_n3gpp: 0
            nas_5gs.nw_feat_sup.vops_3gpp: 1

As above, the len indicates 2, which means there should be 2 octets in the content. According to 3GPP TS24.501, the Octet 4 contains "MCSI" and "EMCN3" two fields.

MCSI: MCS indicator EMCN3: Emergency service support for non-3GPP access indicator

I have tried the latest dev version Wireshark, Wireshark-win64-3.3.0rc0-245-g2060e0202193, still the same result. Please help to check this issue.

Thanks a lot.