PDU Session Release
This MR implements end-to-end PDU Session Release functionality
according to 3GPP TS 38.413 and TS 38.331 specifications.
Reason for Change Previous implementation had incomplete and wrongly
places tunnel cleanup during PDU session release. UP cleanup shall be
done at CUUP, RRCReconfiguration shall be sent after retrieval of
updated CellGroupConfig from the DU. This implies F1 and E1 exchanges
during PDU session release procedure.
Major Changes:
1. RRC PDU Session Release: DRBs and PDU session teardown in NGAP PDU
Session Release Response callback
- Helper Functions: Introduced rm_pduSession,
find_drb_by_pdusession_id and rm_drbs() helpers to locate and clean
up DRBs linked to a specific PDU session
- Targeted Cleanup: RRC PDU Session and per-session DRB removal in
rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE()
- Status Cleanup: Removed unused PDU_SESSION_STATUS_RELEASED status
2. RRC PDU Session Release: Refactor
rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND
- Any PDU session in the pdusession_release_params list that is
present in the RRC list can be set to release, regardless of its
status
- Function Signature Update: Updated function signature and other
minor changes
- Response Handling: rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE is
sent upon completion of RRCReconfiguration
3. RRC PDU Session Release: add missing procedures E1AP Integration:
- Populates E1AP Bearer Modification for each to be released session
- PDCP Enhancement: Added nr_pdcp_release_drbs() to remove all DRBs
linked to a given PDU session in CUUP
- GTP-U Cleanup: GTP tunnel teardown handled in CUUP
e1_bearer_context_modif() using correct F1 or N3 GTP instance
4. NR PDCP/GTP:
- Enhanced Tunnel Deletion Logic: Separate handling for N3 tunnels (1
per PDU session) and F1-U tunnels (1 per DRB)
- New PDCP API Function: Added nr_pdcp_get_drb_ids_for_pdusession()
function to retrieve all DRB IDs associated with a specific PDU
session
5. RRC PDU Session Release: F1AP-based UE Context Modification:
- Replaced direct RRC message transfer with F1AP UE Context
Modification Request for proper retrieval from DU
- Cell Group Configuration: handling of updated CellGroupConfig from
DU ensures DRB release at CU
6. Docs and testing:
- Added PDU session add/remove test cases to 25 PRB RFSIM pipeline
- Documentation: Added PDU Session Release sequence diagram
- Telnet Commands: Added ci command to trigger NGAP PDU Session
Release and ciUE command to trigger establishment of a new PDU
Session
7. Additional fixes:
- UE RLC Management: ensure release of RLC entities
- Unify NG delay control before calling the RRC NGAP handler, for both
Setup and Release
8. Code Cleanup: Cleaned up unused GTP teardown functions.
Closes#867
- Enable telnet server on VNF (gNB) and UE in docker-compose.yaml
- Add new test cases for PDU session management:
* Add PDU session via UE telnet
* Release PDU session via telnet
* Verify connectivity after PDU session release
- Integrate telnet commands into existing container_5g_rfsim_u0_25prb.xml pipeline
- Test cases added before undeploy step in proper execution order
Some CI tasks/commands like Iperf(), Ping() get multiple nodes (via XML
parameter "nodes") to potentially run UEs on different nodes (hosts) at
the same time. However, I argue that this is not good:
- we don't actually use this -- where we specify multiple UEs, it's
always "localhost localhost..."
- it is inconsistent, as we typically have a single "node", not nodes,
and there is a possibility to harmonize (see also next commit)
- if we needed it, there would be better ways to achieve the same.
First, for hardware-based UEs, the ci_infra.yaml can specify different
UEs. For simulated UEs, it would be feasible to have multiple XML
steps run in parallel, e.g., in the XML <parallel> tag, which would
clarify that multiple UEs on different hosts run in parallel
- it reduces code.
Hence, make a single <node> for these XML steps.
By configuring the Jenkins pythonExecutor to match the test machine, we can use
localhost as the node for running individual test cases. This change makes it
easy to move tests across machines, as the only adjustment needed is updating
the pythonExecutor in Jenkins.
With the server object to be passed into ping test, it's not necessary
to either hardcode an IP address or provide a template. Instead, always
fill the IP address, which simplies the Ping() code.
Verify that we don't have an IP address/hardcoded by throwing an
assertion.
This is not really used as of now, because most IPs are hardcoded. See
one of the next commits for the use of this.
To make sure that we have the correct IP, there is some code that
verifies that a hardcoded IP and the CN IP would be the same.
Note: need two separate ci_infra.yaml entries, because
- for FlexRIC, the container name is different (is the tutorial CN)
- for RFsim5G E1, we don't have ext-dn => ping UPF
- pass parameter directly instead of indirectly via class
- harmonize to svr_id to read through common code in the next commits
- pass images to express which images will be deleted
- refactor function to use "with" for cls_cmd, and return success (or
not)
- pass parameter directly instead of indirectly via class
- call it simply "images", to harmonize with clean-function later
- harmonize to svr_id as in the previous commit
- rewrite function to use with-statement with cls_cmd
- optionally pass a tag to use (which will be used in a test, and can be
used to pull flexric)
- Introduce Pull_Image() which does the actual pulling, can pull from
any registry, and will be reused in the case of pulling from cluster.
Use a script, which can be tested independently of CI code (by running
it on the host on which it will be used), and print the directory that
has been prepared in the HTML. Also, in the description, use the
infinitive/imperative(?) of the verb to harmonize with other steps.
- no need to specify "single-ue" profile when running iperf test for 1 UE only
- default profile "balanced" can be used instead, computes BW for 1 UE correctly
Ensure that the UE has an IP address before continuing the test.
Otherwise, it might happen we ping before the UE is connected.
Do not do this in do-ra and phytest, as they use --noS1, which implies
statically assigned IP address, so IP address check always succeeds(!).
Make RFsim start up faster by starting core and RAN start at the same
time. This speeds up because we do not wait for "healthy" containers
serially, but parallely.
For the RAN, it is safe to start gNB and UE at the same time in SA mode
(as the UE will only attach once the radio, and hence the full gNB, is
ready).
We do not start in parallel in do-ra and phytest, as in these modes the
gNB first has to write a UE-specific configuration file. If we start
both gNB and UE at the same time, the UE might try to read the file
before it is written, leading to a failure.
Robert Schmidt