CS Fallback in NextEPC

Romeu Medeiros medeiros at medeiros.eng.br
Sun Jul 14 01:48:21 UTC 2019


Hello Sukchan,

In some situations the CSFB will be realized in a partner network, (Another
GSM/3G Network), with this the MNC and MCC will be different.

I suggest this configuration format for this case:

    sgsap:
      addr: 127.0.0.2
      port: 29119
      plmn_id:
        mcc: 001
        mnc: 01
      dest_plmn_id:
        mcc: 002
        mnc: 02
      tac: 4130
      lac: 43690


With this, the RegistredLAI will have this information MCC: 002, MNC: 02
and LAI: 43690.

If you agree with this I can implement this.

Thanks

Romeu Medeiros


On Sat, Jul 13, 2019 at 9:03 PM Romeu Medeiros <medeiros at medeiros.eng.br>
wrote:

> Hello Sukchan,
>
>
> I already go out from the lab today, but Monday I will made this test that
> you ask for.
>
>
> Have a great day there.
>
> Romeu Medeiros
>
> Em sáb, 13 de jul de 2019 às 21:01, Sukchan Lee <acetcom at gmail.com>
> escreveu:
>
>> Hi Romeu,
>>
>> I'm really appreciate testing CSFB even though I have never been testing
>> this feature in the lab.
>>
>> BTW, I have one question. If we want to remove Security-Related IE in UE
>> Context Modification Request,
>> I think NextEPC should not derive kENB in Extended Service Request
>> handler.
>>
>> Nevertheless, I've merged your pull request since it is properly worked
>> at first. ^^;
>>
>> If your lab is available, could you test one more by removing the
>> following code?
>>
>> In src/mme/emm-handler.c
>> 586     if (SECURITY_CONTEXT_IS_VALID(mme_ue)) {
>> 587         mme_kdf_enb(mme_ue->kasme, mme_ue->ul_count.i32,
>> mme_ue->kenb);
>> 588         mme_kdf_nh(mme_ue->kasme, mme_ue->kenb, mme_ue->nh);
>> 589         mme_ue->nhcc = 1;
>> 590     }
>>
>> Just test it. If my expectation is true, I will fix all other things.
>>
>> Thank you for your GREAT job!
>>
>> Best regards,
>>     Sukchan
>>
>>
>>
>>
>>
>> On Sun, Jul 14, 2019 at 8:04 AM Romeu Medeiros <medeiros at medeiros.eng.br>
>> wrote:
>>
>>> Hello Sukchan,
>>>
>>> Now after remove this everything run correctly.
>>>
>>> [image: image.png]
>>>
>>> I will made the change more beatiful and pull the modification to the
>>> git to you aprove.
>>>
>>> Thanks
>>>
>>> Romeu Medeiros
>>>
>>> On Sat, Jul 13, 2019 at 6:50 PM Romeu Medeiros <medeiros at medeiros.eng.br>
>>> wrote:
>>>
>>>> I found this in the 3GPP documentations [1]:
>>>>
>>>> [image: image.png]
>>>>
>>>> I will change the code to send only the CSFallback indicator in this
>>>> case to see if can solve the problem.
>>>>
>>>> Thanks
>>>>
>>>> Romeu Medeiros
>>>>
>>>> 1.
>>>> https://www.etsi.org/deliver/etsi_ts/136400_136499/136413/09.10.00_60/ts_136413v091000p.pdf
>>>>
>>>> On Sat, Jul 13, 2019 at 6:35 PM Romeu Medeiros <
>>>> medeiros at medeiros.eng.br> wrote:
>>>>
>>>>> Hello Sukchan and friends.
>>>>>
>>>>> I'm trying to use the CSFB in test lab, and every time that nextepc
>>>>> send the UEContextModificationRequest, the UE respond with an
>>>>> UEContextModificationFaliure [ Protocol-cause=semantic-error ].
>>>>>
>>>>> [image: image.png]
>>>>>
>>>>> I'm looking why I'm getting this. Someone have any idea?
>>>>>
>>>>> Thanks
>>>>>
>>>>> Romeu Medeiros
>>>>>
>>>>> On Thu, Jul 11, 2019 at 12:15 PM Sukchan Lee <acetcom at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Dear Osmocom & NextEPC Community,
>>>>>>
>>>>>> Today I've added CS Fallback and released NextEPC v0.5.0
>>>>>>
>>>>>> So, I'd just like to test this part with Osmocom project, but it
>>>>>> seems to be a difficult task. The reason is why I have little knowledge
>>>>>> about 2G/3G. Nevertheless, I will try to do it
>>>>>>
>>>>>> BTW, I don't know if there is anyone who wants to integrate this big
>>>>>> thing.
>>>>>> Even though I'm not sure if this will help, but let me introduce the
>>>>>> configuration of the NextEPC.
>>>>>>
>>>>>> To use SGsAP, change the mme.conf as follows:
>>>>>>
>>>>>> #
>>>>>> #  <sgsap>
>>>>>> #
>>>>>> #  o Single MSC/VLR
>>>>>> #    sgsap:
>>>>>> #      addr: 127.0.0.2
>>>>>> #      plmn_id:
>>>>>> #        mcc: 001
>>>>>> #        mnc: 01
>>>>>> #      tac: 4130
>>>>>> #      lac: 43690
>>>>>> #
>>>>>> #  o Multiple MSC/VLR
>>>>>> #    sgsap:
>>>>>> #      - addr: 127.0.0.2
>>>>>> #        plmn_id:
>>>>>> #          mcc: 001
>>>>>> #          mnc: 01
>>>>>> #        tac: 4131
>>>>>> #        lac: 43692
>>>>>> #      - addr
>>>>>> #         - 127.0.0.3
>>>>>> #         - fe80::2%lo0
>>>>>> #        plmn_id:
>>>>>> #          mcc: 001
>>>>>> #          mnc: 01
>>>>>> #        tac: 4132
>>>>>> #        lac: 43692
>>>>>> #      - name: msc.open5gs.org
>>>>>> #        plmn_id:
>>>>>> #          mcc: 001
>>>>>> #          mnc: 01
>>>>>> #        tac: 4133
>>>>>> #        lac: 43693
>>>>>> #
>>>>>>
>>>>>> FYI, I also attach the pcap that I run with nextepc simulator as
>>>>>> below.
>>>>>>
>>>>>> $ ./tests/testcsfb
>>>>>> mo-idle-test        : SUCCESS
>>>>>> mt-idle-test        : SUCCESS
>>>>>> mo-active-test      : SUCCESS
>>>>>> mt-active-test      : SUCCESS
>>>>>> All tests passed.
>>>>>>
>>>>>> Feel free to raise any questions about this things.
>>>>>>
>>>>>> Best Regards,
>>>>>>     Sukchan
>>>>>>
>>>>>>
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