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@medeiros.eng.br> wrote:

Hello Sukchan,

Now after remove this everything run correctly.

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@medeiros.eng.br> wrote:

I found this in the 3GPP documentations [1]:

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@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 ].

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@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