While experimenting with CSFB, it was observed that when the UE returns
to E-UTRAN after a CS call, the UE performs a Tracking Area Update
with a combined Tracking Area/Location Area update and IMSI attach.
Currently, Open5GS's MME simply responds with a TAU Accept message
but does not inform the MSC/VLR.
As a result, no further MT (Mobile Terminated) CS/SMS services are possible
in cases where the MSC/VLR only attempts paging on GERAN.
However, some MSC/VLR implementations with fast fallback may still attempt
paging on E-UTRAN, allowing MT CS/SMS services to function intermittently.
According to 3GPP TS 29.118 Section 5.2.2 Procedures in the MME,
specifically Section 5.2.2.2.1, if the timer Ts6-1 is not running,
the MME shall start the location update for non-EPS services procedure
upon receiving a combined Tracking Area Update Request indicating
combined TA/LA updating with IMSI attach. However, SGs timers are not
implemented in Open5GS, which is a separate issue.
To comply with the specification and ensure that the MSC/VLR is informed
when the UE becomes reachable via SGs, the following changes have been
implemented:
1. Delay UEContextReleaseCommand:
When the active_flag is set to 0, the UEContextReleaseCommand is now delayed
until the MME receives the TAU Complete message from the UE. This ensures
that the UE has acknowledged the new P-TMSI before the network releases
the context, maintaining proper synchronization between the UE and the network.
2. Include Mobile Identity Only When P-TMSI Changes:
The Mobile Identity is now included in the Attach/TAU Accept messages
only when the MSC/VLR updates the P-TMSI. This ensures that the UE receives
the Mobile Identity information solely when there is an actual change
in the P-TMSI, preventing unnecessary or incorrect handling
of TAU Complete messages.
3. Send SGsAP-REALLOCATION-COMPLETE Conditionally:
The SGsAP-REALLOCATION-COMPLETE message is now sent to the MSC/VLR
only upon receiving a Attach/TAU Complete message from the UE.
This confirmation indicates that the UE has successfully updated its P-TMSI,
ensuring that the MSC/VLR is accurately informed of the change.
4. Handle P-TMSI Confirmation:
When the MSC/VLR updates the P-TMSI, Open5GS stores the new P-TMSI
in the next field of the mme_ue structure. Upon receiving the TAU Complete
message from the UE, indicating acknowledgment of the new P-TMSI,
Open5GS confirms the update by transferring the P-TMSI from the next field
to the current field. This ensures that the MME maintains an accurate and
up-to-date record of the P-TMSI as confirmed by the UE.
If the UE continuously attempts to Attach while changing PDN Type,
it will cause the wrong IP to be assigned.
(e.g PDU-Type : IPv4v6 -> IPv4 -> IPv4v6)
This is because we use two variables at the same time,
one to read and store the Static IP from the Subscriber DB and
one to store the IP assigned from SMF, called session->paa.
When the UE attaches with PDN-Type set to IPv4v6,
MME saves the allocated IP in session->paa.
However, MME thinks it has been assigned a static IP based on the information
in session->paa, so changing the PDN-Type may result in the wrong IP
being assigned.
To solve this problem, I separated the variable(session->paa) that stores
the allocated IP received from SMF and the variable(session->ue_ip) that stores
the Static IP read from the Subscriber DB.
Therefore, the information read from the Subscriber DB
(session->session_type and session->ue_ip) should not be modified.
First of all, it crashes when creating a Dedicated Bearer
on the default Session that is created for the first time.
This behavior should be possible, so the related ASSERT is removed.
Next, the InitialContextRequest is modified
during the Attach Request to include the first Bearer.
Finally, there was an issue where trying to create a Dedicated Bearer
with SGsAP enabled resulted in an InitialContextSetupRequest message
with a PTI of zero. This is because MME initializes the PTI to 0
upon receiving the Create Bearer Request while processing SGsAP.
All of these issues has been fixed.
1. According to ETSI TS 129 118 4.1, if the Network Access Mode (NAM) is set
to "Packet only," no SGs association should be established.
2. If the NAM is set to "Packet and Circuit," and the SGs association is
rejected by the CS core, this rejection should only impact
the SGs association itself and not result in a UE attach rejection
for a UE with a valid HSS account.
o Generate the private key as below.
$ openssl genpkey -algorithm X25519 -out /etc/open5gs/hnet/curve25519-1.key
$ openssl ecparam -name prime256v1 -genkey -conv_form compressed -out /etc/open5gs/hnet/secp256r1-2.key
o The private and public keys can be viewed with the command.
The public key is used when creating the SIM.
$ openssl pkey -in /etc/open5gs/hnet/curve25519-1.key -text
$ openssl ec -in /etc/open5gs/hnet/secp256r1-2.key -conv_form compressed -text
In ausf/udm.yaml
hnet:
o Home network public key identifier(PKI) value : 1
Protection scheme identifier : ECIES scheme profile A
- id: 1
scheme: 1
key: /etc/open5gs/hnet/curve25519-1.key
o Home network public key identifier(PKI) value : 2
Protection scheme identifier : ECIES scheme profile B
- id: 2
scheme: 2
key: /etc/open5gs/hnet/secp256r1-2.key
o Home network public key identifier(PKI) value : 3
Protection scheme identifier : ECIES scheme profile A
- id: 3
scheme: 1
key: /etc/open5gs/hnet/curve25519-1.key
o Home network public key identifier(PKI) value : 4
Protection scheme identifier : ECIES scheme profile B
- id: 4
scheme: 2
key: /etc/open5gs/hnet/secp256r1-2.key
Related to #1779
In the past only GTPv2C was supported, and had the "gtp" generic prefix.
Later on, GTPv1C support was added, and "gtp1" prefix was used.
Let's move GTPv2C specific bits to have "gtp2" prefix too, and leave
"gtp" prefix for generic stuff among different GTP versions.
commit 58d790f4916319b274c2c8a82b6226dc3f79258e
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 22:05:38 2020 +0000
udpate it
commit 5c06b8fa9114dc7391208d523cf850a3ca3f78d5
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 16:01:02 2020 +0000
update it
commit 19909f9d9e20f429bd06300e9ba2cfaef855c9b2
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 15:52:13 2020 +0000
update it
commit b7f2bb3681aa512dcb621e4662c90d7277863707
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 15:48:18 2020 +0000
update it
commit 53f3004467a81a0702d9c1ee3e29f4d4d29ff22c
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 15:32:30 2020 +0000
update it
commit e295ec4537c443cd6253592a9e31e151fc0bb827
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 14:50:23 2020 +0000
update it
commit 435edd22ba8118b31855b88d6974d9f757758da2
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 14:39:43 2020 +0000
update it
commit 49872a99f13476bd73a44150d18c66ad713ef699
Author: Sukchan Lee <acetcom@gmail.com>
Date: Thu Aug 13 14:36:30 2020 +0000
update it
