In an Inter-RAT setup a UE could perform a TAU coming from a 2G/3G network.
In that case the UE/MS is unknown to the MME and it should request the
SGSN context (MM, PDP) from the old SGSN. This is done through the following
GTPv1C message exchange on the Gn interface of SGSN and MME:
SGSN <- MME: SGSN Context Request
SGSN -> MME: SGSN Context Response
SGSN <- MME: SGSN Context Acknowledge
Diagram with full set of steps can be found at 3GPP TS 23.401 D.3.6.
This commit doesn't aim to be a complete implementation of the mentioned
procedure, since it's quite a complex one, with lots of fields and logic
required. This so far only implements in general the minimally
successful case by filling as much as possible the required set of
fields.
This will allow for a base onto which do incremental improvements and
fixes while testing against UEs and SGSNs (such as osmo-sgsn, which
doesn't yet support this procedure but will potentially earn it soon).
The reverse direction, aka UE issuing cell reselection 4G->2G was
already implemented (same as here, initial non-complete implementation)
in open5gs-mmed in commit 3d693da73e.
Related: https://osmocom.org/issues/6294
Allow network operators to omit the time zone in the 4G EMM Information
and 5G Configuration Update. This is useful for better compatibility
with some UEs.
The parameter is optional according to:
* 4G: 3GPP TS 24.301 Table 8.2.13.1
* 5G: 3GPP TS 24.501 Table 8.2.19.1.1
* Cancel Location while Idle Fix
* Forgot about SGSAP on MME Change.
Added "action" to sgsap_send_detach..
* Make handle_clr uniform with other handlers
* Added Robustness for Any Detach Type
* Memory wasn't freed upon CLR for unknown IMSIs
* Moving MME Detach to new PR
* Add Diameter Dictionary Elements
* Initial IDR Framework
* Resolve Compile Issues
* Moving Closer
* Compile error
* Somewhat Working stuffing Code
* Add Timestamp Changes
* Cleanup some of this code. mme_s6a_handle_idr in s6a-handler.c removed for now, since it will only come in handy when IDR flag is set to request current location, which would involve breaking out into paging. I think there's a few other things we can do just within fd-path first.
* further removal of mme_s6a_handle_idr
When a UE that requests slices tries to connect and there are no slices configured, the reject message is:
5GMM cause = 0x7 (5GS Services not allowed)
however it should be:
5GMM cause = 0x3e (No network slices available)
All 5GMM cause value in reject message is reviewed in this commit
The network access mode of HSS has been changed to 0 (Packet and Circuit).
Versions of MME prior to v2.4.2 did not use this value. Open5GS set
the attach result of Attach Complete message as it is by looking
at the attach type of the Attach Request message.
Now, if the network access mode of HSS is set to 2 (Only Packet),
this value is affected by MME from v2.4.3. Regardless of the attach type
of the Attach Request, the MME will set EPS Only to the attach result
of Attach Complete.
All process will be forcely exited if it failed to encode the S1AP/NGAP/GTP/PFCP message. It is to make sure there was no problem with the encoding of open5gs.
The AMF shall assign a new 5G-GUTI for a particular UE:
a) during a successful initial registration procedure;
b) during a successful registration procedure
for mobility registration update; and
c) after a successful service request procedure invoked as a response
to a paging request from the network and before the release
of the N1 NAS signalling connection as specified in subclause 5.4.4.1.
The AMF should assign a new 5G-GUTI for a particular UE
during a successful registration procedure
for periodic registration update. The AMF may assign a new 5G-GUTI
at any time for a particular UE by performing
the generic UE configuration update procedure.
If both Delete-Session-Request/Response and
UEContextReleaseCommand/UEContextReleaseComplete are failed at the same time,
UE cannot attach to the EPC infinitely.
So, I've add the protection code
if timer expires when MME does not receive Delete-Session-Response.
* HACK: Don't retransmit InitialContextSetupReq
Related: #256
* HACK: Don't use buggy sa1p_copy() in eNBConfigTransfer
Related: #257
* mme: don't reject with 'IMSI is unknown in HLR' (permanent reject)
* MME: Implement S6a result -> EMM cause code mapping
Closes: #263
* Spencer: modification to Haralds fix because macros are now renamed
* MME: don't assert on MAC failures of uplink NAS frames
Closes: #267
* MME: Avoid ogs_assert() in many situations
We don't want to crash the entire program just because a message
received from an external entity didn't match some of our expectations.
* compiles fine, checked DIFFs and only difference is the ogs_assert -> ogs_expect
Pau Espin
Oliver Smith
Sukchan Lee
jmasterfunk84
Kenny Barlee
Spencer Sevilla