The idea is to reestablish all RLC entities (it's a new UE, and we set
reestablishRLC on all bearerrs), so we should reestablish all RLC
entities on gNB side as well, without any additional loop.
Co-authored-by: Roberto Magueta <rmagueta@allbesmart.pt>
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
This commit implements proper PDU Session Release handling across
RRC, PDCP, F1AP, E1AP to ensure clean resource cleanup when
a PDU session is terminated.
Key changes:
NGAP:
In `rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND()`:
* Populates E1AP Bearer Modification for each released session
* If a CU-UP is connected, triggers `bearer_context_mod()` for PDU teardown
PDCP:
* Added `nr_pdcp_release_drbs()` to remove all DRBs linked to a given PDU session
* Called from `e1_bearer_context_modif()` for correct clean-up during session release
F1AP UE Context Modification:
Replace direct RRC message transfer with F1AP UE Context Modification Request
to properly handle PDU session release according to 3GPP TS 38.331.
3GPP TS 38.331 `5.3.5.6.4 DRB release` says: whether or not the RLC and MAC entities associated
with a PDCP entity are reset or released is determined by the CellGroupConfig. Thus,
updated CellGroupConfig needs to be received by the UE. This has to be retrieved by CUCP
from the DU. Therefore:
After receiving an NGAP_PDUSESSION_RELEASE_COMMAND, the CUCP shall:
1) forward (store for later) the NAS PDU to the UE, if present as per 3GPP TS 38.413, and
2) send a UE Context Modification to the DU with the list of DRBs to release
and the RRC container (RRCReconfiguration with NAS PDU)
After reception of UE Context Modification Response, the list of drbs to release
is prepared based on PDU session status PDU_SESSION_STATUS_TORELEASE
in rrc_gNB_generate_dedicatedRRCReconfiguration and then encoded
in drb_ToReleaseList for a new RRCReconfiguration with the new cellGroupConfig.
Key changes:
* rrc_gNB_generate_dedicatedRRCReconfiguration_release() now uses F1AP UE Context
Modification Request instead of direct RRC transfer
* Only DRBs to be released are now added to the list.
* The ASN.1 memory allocation is entirely done in build_RRCReconfiguration_IEs
* No longer needed to store ASN1 struct in UE context
GTP-U:
* Previous implementation had incomplete tunnel cleanup during PDU session release
- Missing distinction between N3 (PDU session level) and F1-U (DRB level) tunnels
- Lack of proper DRB identification for F1-U tunnel deletion
Major Changes:
* GTP tunnel teardown now handled in `e1_bearer_context_modif()` using the correct
F1 or N3 GTP instance (`newGtpuDeleteOneTunnel()`)
* Enhanced Tunnel Deletion Logic (cucp_cuup_handler.c):
- Separate handling for N3 tunnels (1 per PDU session) and F1-U tunnels (1 per DRB)
- Added proper DRB identification for F1-U tunnel cleanup
- Improved error handling with detailed logging for each tunnel deletion
- Enhanced logging to distinguish between N3 and F1-U tunnel operations
* New PDCP API Function (nr_pdcp_oai_api.c/h):
- Added nr_pdcp_get_drb_ids_for_pdusession() function
- Enables retrieval of all DRB IDs associated with a specific PDU session
- Supports proper F1-U tunnel cleanup by providing DRB identifiers in CUUP
* Enhanced GTP Interface (gtp_itf.cpp/h):
- Modified newGtpuDeleteOneTunnel() to accept tunnel_type parameter
- Improved logging to distinguish between PDU session and DRB tunnel types
- Better error messages for tunnel deletion failures
- Enhanced debugging information for remaining tunnels
Clean-up:
* Ensured xid tracking works consistently between PDU Session Establishment (with NAS PDU)
and dedicated RRCReconfiguration
* Add function to release GTP-U tunnel in Bearer Context Modification Request handler
* Do not send rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE when no PDU session are to
be released: it is sent upon completion of the RRCReconfiguration and needs to contain
released PDU Sessions (mandatory IE), therefore it is no necessary to send it in case
there is no PDU session to release.
Related to #867
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>
gNB: modify RLC configuration applied for SRB1 during RRCReestablishment
TS 38.331 clause 5.3.7.4 specifies to apply the configuration defined in
9.2.1 for SRB1 at UE side. This implies that the gNB also has to apply
sn_field_length = 12, but there are no implications on the other RLC
parameters.
As wrong timer values break SRB1 e.g. for long RTT NTN scenarios, this
commit switches to using the RLC timer values provided in the
configuration file. Currently we still set poll_pdu, poll_byte and
max_retx_threshold to the values defined in 9.2.1, but this can be
changed.
TS 38.331 clause 5.3.7.4 specifies to apply the configuration defined in 9.2.1 for SRB1 at UE side.
This implies that the gNB also has to apply sn_field_length = 12, but there are no implications on the other RLC parameters.
As wrong timer values break SRB1 e.g. for long RTT NTN scenarios, this commit switches to using the RLC timer values provided in the configuration file.
Currently we still set poll_pdu, poll_byte and max_retx_threshold to the values defined in 9.2.1, but this can be changed.
- Add missing ASN_STRUCT_FREE for NR_MeasurementTimingConfiguration in ue_context_setup_request
- Fix 64-byte MTC sequence leak in get_nr_mtc → SEQUENCE_decode_uper
AddressSanitizer backtrace:
Direct leak of 64 byte(s) in 1 object(s) allocated from:
/#0 0x7dcfcb8b4a57 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
/#1 0x591fcc59b67d in SEQUENCE_decode_uper /home/guido/repo/openairinterface5g/develop/cmake_targets/ran_build/build/openair2/RRC/LTE/MESSAGES/constr_SEQUENCE_uper.c:37
/#2 0x591fcc57eaa1 in uper_decode /home/guido/repo/openairinterface5g/develop/openair2/RRC/LTE/MESSAGES/uper_decoder.c:83
/#3 0x591fcbdbedeb in get_nr_mtc /home/guido/repo/openairinterface5g/develop/openair2/LAYER2/NR_MAC_gNB/nr_radio_config.c:4216
/#4 0x591fcbd58188 in ue_context_setup_request /home/guido/repo/openairinterface5g/develop/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c:635
/#5 0x591fcbb92568 in nr_initiate_handover /home/guido/repo/openairinterface5g/develop/openair2/RRC/NR/rrc_gNB_mobility.c:218
/#6 0x591fcbb9a37f in nr_rrc_trigger_n2_ho_target /home/guido/repo/openairinterface5g/develop/openair2/RRC/NR/rrc_gNB_mobility.c:526
/#7 0x591fcbaf7608 in rrc_gNB_process_e1_bearer_context_setup_resp /home/guido/repo/openairinterface5g/develop/openair2/RRC/NR/rrc_gNB.c:2640
/#8 0x591fcbafab7b in rrc_gnb_task /home/guido/repo/openairinterface5g/develop/openair2/RRC/NR/rrc_gNB.c:3019
/#9 0x7dcfca294ac2 in start_thread nptl/pthread_create.c:442
Root cause: ue_context_setup_request allocated NR_MeasurementTimingConfiguration via
get_nr_mtc() but never freed it after creating the measurement gap configuration.
The create_measgap_config function only reads from the structure and doesn't take
ownership, so the caller must free it.
Remove the --usim-test option: to my knowledge, it's not used by users,
and is misleadingly placed in various places where there should not be a
difference w.r.t. USIM configuration.
When making the changes, I assumed that --usim-test would be 0 (the
default), which is the case in all executables when not specified in
options except for the nr_dlsim, nr_pbchsmi, nr_ulsim simulators.
The only exception is the initialization of PDCP from the MAC, which is
not correct (the PDCP is in the CU, so it does not make sense to call it
from the MAC which is in the DU). Instead, always initialize from main,
even in the NSA case (NSA was covered by the incorrect initialization
from MAC).
This in turn let to some more cleanup around function du_rlc_data_req().
After receiving GTP packets at the DU, they were given to the PDCP to
enqueue the packet at RLC. This does not work anymore, since the PDCP is
not initialized; it also does not seem necessary, as this enqueue
functionality is necessary to decouple PDCP and RLC to avoid deadlocks
in monolithic, but in split-mode, this cannot happen. Instead, call
directly into the RLC when receiving GTP packets.
Measurement gaps
Scheduling measurement gaps to provide sufficient time for the UE to
re-tune its transceiver to the target carrier, complete the set of
measurements and then re-tune its transceiver back to the original
carrier.
The changes done in this commit are to contribute the supporting changes
for the existing "Initial support for RedCap" feature in gNB.
In this patch, handle and store the RedCap related IE's present in "NR
UE Capability Information" msg which are
- 'supportOfRedCap-r17'
- 'supportOf16DRB-RedCap-r17'
- 'longSN-RedCap-r17'
- 'am-WithLongSN-RedCap-r17'
use 'longSN-RedCap-r17' and 'am-WithLongSN-RedCap-r17' IEs to set the SN
length to either 12 Bit or 18 Bit accordingly.
Various fixes for UE handling, HO doc updates
- On release request, search both attach and connected list to free a UE.
- on DU disconnect, only release the correspnonding UE contexts.
- When no AMF for the UE, auto-release the UE (NGAP would also send an
answer, but better check first)
- implement a "grace period" before the DU/MAC automatically releases a
UE: this is to avoid cases in which (for whatever reason) the UE
release request is not honored by the CU. In order to not fill up UE
contexts unnecessarily, the DU will eventually (after 10s) drop the UE
context
- some clarification in HO tutorial
When the RA procedure fails at Msg4, we trigger UL failure and send a
message to the CU to request release. There was a bug in that upon the
ensueing release command, we did not search in the attach list (only
connected list). However, the UE failing at Msg4 does not have
transitioned to the connected list yet, thus not freeing the context.
Fixes: 8f62baefa6 ("Use list of UEs during RA instead of array of RA
processes)"
NR RRC Reject UE
Improvements in procedures to handle RRCReject message both at gNB and
UE. At gNB we send RRC Reject if the UE cannot be given resources to go
into connected mode.
Similarly to the commit "Use F1 UE context setup/modif Request in
stack", we do both UE context setup/modification response at once
because of some functions that are shared by the MAC message handler.
Use the new, tested F1 UE context setup request and modification
requests in the stack.
We have to do both at once, because there are some functions that are
used by handlers for both messages, notably
- handle_ue_context_drbs_setup()
- handle_ue_context_srbs_setup()
(+ and some functions called by those two). For instance, the first uses
the (new/old) type f1ap_drb_to_be_setup_t/f1ap_drb_to_setup_t which is
shared. The alternative would be to duplicate the functionality
temporarily, and I want to avoid unnecessary code churn.
Fix NR reestablishment by implementing the "DRB-suspend" at the MAC.
This means that the during reestablishment, gNB MAC discards received
DRB packets, and does not schedule DRB. Fix a couple of additional
issues in reestablishment. # Please enter a commit message to explain
why this merge is necessary,
For additional information, see
https://gitlab.eurecom.fr/oai/openairinterface5g/-/merge_requests/2668#note_119369
The spCellConfig is to be dropped during reestablishment and to be
applied after reconfiguration. Implement this using the
RRCReconfigurationComplete acknowledgment from the CU to the DU,
applying the spCellConfig if present (which signals a prior
reestablishment). Remove a prior flag that is not needed anymore, and
do not "guess" when is the reconfiguration, because it is now handled in
the case of the ack.
The spCellConfig is not relevant as long as we use a common search space
for DCIs (and the activation of dedicated search space happens after
applying spCellConfig). For PUCCH, there is the PDSCH transmission of
RRCReconfiguration which gets ack'ed in the default PUCCH.
RRCReconfigurationComplete is sent in PUSCH (again through common
search space). In theory, there cannot be another PUCCH before the
application of spCellConfig, as all bearers are still suspended, and
there should not be another SRB1 transmission in the meantime, as only
one RRC transaction can be active at a time.
Co-authored-by: francescomani <email@francescomani.it>
Add a flag for each RB that tracks suspension state. Mark all RBs
(except SRB1) as suspended on reestablishment, and de-suspend on
reconfiguration. Only check RLC status for non-suspended RBs. For UL
data traffic, check that DRB/SRB2 exist (SRB1 should be there as soon as
the UE context exists).
- remove hardcoded values
- adapt gNB RRC code
- adapt gNB MAC code
- adapt physical simulators, where we put the hardcoded values
that were everywhere else before; if there is a need for those
simulators to get configurable values, more work is needed
(but it's doubtful that it is needed)
A number of radio-related RRC parameters, e.g., CellGroupConfig,
"originate" at the DU and are sent to the CU for forwarding to the UE
only. Similarly, there are additional parameters, e.g., RLC-BearerConfig
(part of CellGroupConfig), that originate at the DU.
Hence, the DU decides about these parameters, depending on the MAC state
and capabilities. To clarify this, move the existing
openair2/RRC/NR/nr_rrc_config.{c,h} => openair2/LAYER2/NR_MAC_gNB/nr_radio_config.{c,h}
So that developers know that while those are RRC parameters, they
originate at the DU.
In other words, the CU/RRC is not supposed to use any of these functions
in the RRC. Correspondingly, includes of this file have been cleaned up
(and when they are not necessary at the MAC as well).
Signal gNB-DU config update CellStatus from DU to CU
Add the cell status to gNB-DU configuration update message, including
test. Use the gNB-DU configuration update to signal the cell status in
the stack.
This IE was not included in a previous refactoring round, but is at
least necessary to be decoded when interoperating with the OSC O-DU.
Use the gNB-DU configuration update to signal the cell status in the
stack. At the DU, modify the code to always send this message --
previously, we only sent this message if a SIB1 update was necessary,
but now it's always, only including SIB1 updates if necessary.
At the CU, as we don't really have a use as of now, print the
information, but don't do anything with it.
- rewrite add_UE_to_list() and rewrite remove_UE_from_list() to simplify
list handling
- return pointer from get_new_nr_ue_inst(); it's completely freed by
delete_nr_ue_data()
- have add_new_UE_RA() add UE context to access list; remove with
nr_release_ra_UE()
- have add_connected_nr_ue() only add UE to connected list; to move from
access to connected use transition_ra_connected_nr_ue(); remove with
mac_remove_nr_ue() as previously
- free memory on problems during RA
- add some documentation
- in NSA/HO: check for pre-configured RA process
- there are asserts in all functions to clarify when a UE has RA
maki
