3GPP TS 29.244 7.2.2.4.2 documents that the peer will set SEID=0 in the
response when we request something for a session not existing at the peer.
If that's the case, we still want to locate the local session which
originated the request, so let's store the local SEID in the xact when
submitting the message, so that we can retrieve the related SEID and
find the session if we receive SEID=0.
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.
The use of the Gy interface (SMF acting as CTF towards an OCS node) is
mandated through configuration file. Default value "enable: auto" will
only make use of it in case a Diameter peer announcing support for the
Credit-Control Application is found.
Upon subscriber session creation, and after auth check over Gx, the SMF
will create a Gy session with the OCS and only after that step the SMF
will accept the session back to the subscriber.
The OCS may then grant some traffic volumes/time and ask to be notified
back with updated measurements.
In order to get the measurements, the SMF relies on PFCP URR configured
to the UPF through Session Repoort Request messages.
When closing the subscriber session, the SMF will also terminate the Gy
session at the OCS.
So far only some specifics parts of the Gy interface as well as the PFCP
side are implemented. Those should be enough to at least have
volume/time thresholds granted by the OCS, which then will be able to
track subsriber resource use.
This patch doesn't implement the OCS side of the Gy interface, that's
left as a future exercise. The interface was tested using an OCS
emulator implemented in TTCN-3 [1]
[1] https://cgit.osmocom.org/osmo-ttcn3-hacks/
TODO:
* Use an event for the report, like SMF_EVT_N4_TIMER?
* Properly set Service identifier in Gy CCR
* SMF: Properly set pkt/octet volumes in Gy CCR
** Update when receiving PFCP Modify Response.
* Figure out best way to require Gy through config file in open5gs-smfd.
* Create a new sess-sm.c which handles smf_sess_t state through
Gx+Gy+PFCP creation, modification and tear down. This way we can do
stuff in parallel, for instance Gx+Gy. It will alsoavoid duplicating
some code paths due to Gy being optional.
The "Report Triggers" is sent SMF->UPF to tell in which situations a
report should be sent.
The "Usage Report Trigger" is sent UPF->SMF to indicate which situation
triggered the report.
* [PFCP] Fix trailing whitespace in message generation files
* [PFCP] message gen: Support multiple URR ID IEs in Create PDR group
* [PFCP] Support associating multiple URRs to a PDR
According to 3GPP TS 29.244:
"""
A PDR shall contain:
- zero, one or more URRs, which contains instructions related to traffic measurement and reporting.
"""
These will be further needed in PFCP in the future, as well as in other
Diameter based interfaces (such as Gy).
Let's put all implementation details in APIs so that devs don't need to
care about those details every time.
* [PFCP] Fix trailing whitespace
* [PFCP] Fix wrong endianess enc of some URR values
u32 tlvs are already converted to big endian automatically. Manually
doing so ends up in double conversion and hence in wrong endianness
being sent over the wire.
Similar issue was also fixed recently in the PFCP decoding path.
Related: https://github.com/open5gs/open5gs/issues/1349
Bostjan Meglic
Sukchan Lee
Pau Espin
Safa Orhan