As in deba3ae066 ("Reset CU-UP E1 UE contexts after E1 Setup
Response"), the CU-CP should reset the E1 UE contexts after E1 Setup
Response. 38.463 sec. 8.2.3 says
> This procedure also re-initialises the E1AP UE-related contexts (if
> any) and erases all related signalling connections in the two nodes like
> a Reset procedure would do.
In the case of CU-CP, this is a bit more complicated. More precisely, we
need to wait for the CU-UP to be available again before informing the DU
about the loss (implemented via an F1 Reset message), because otherwise,
the UE might reconnect immediately, before the CU-UP is online again.
Hence, on connection loss, we mark affected UEs (by setting their E1
association ID to 0); as long as the CU-UP does not connect, nothing
will happen (but UEs don't have user plane). Upon CU-UP connecting
again, we request release of the UEs via NGAP (similarly to what is done
if the DU goes offline, see invalidate_du_connections()), free the UE
contexts locally, and send an F1 Reset message to the DU, because
38.473 sec 8.2.1.2.1 says
> a failure at the gNB-CU [...] has resulted in the loss of some or
> all transaction reference information [...] a RESET message shall be
> sent to the gNB-DU.
The core should accept and send an NGAP release command message; since
no UE contexts are to be found (already deleted), the CU-CP will just
send a release complete (together with some warnings).
It might be possible to more gracefully handle the situation (e.g., as
described in 38.401 section 8.9.5 "Change of gNB-CU-UP"), but
- we lack the PDCP SN exchange
- the current procedure has the advantage of being equivalent to
"restart of the entire gNB", with less downtown.
The next commit will use rrc_remove_ue() to delete a CU(-CP+-UP)
context. However, we don't send NGAP UE context release at that moment
(we will instead *request* the release); more generally, it's not clear
that every user of rrc_remove_ue() wants to actually send this message.
Hence, refactor the code by separately calling
rrc_gNB_send_NGAP_UE_CONTEXT_RELEASE_COMPLETE() where appropriate.
Bearer context setup request and modification request messages
differ in various IEs according to 9.2.2 of 3GPP TS 38.463, e.g.
the Bearer context setup request does not contain a list of
DRBs to modify and does not contain an UP TL configuration.
Thus, the goal of this commit is to split the setup request message
and the modification request into two different structs:
* adopt e1ap_bearer_mod_req_t where necessary (e.g. fill_e1_bearer_modif)
Also, reorganized existing struct members according to specs:
* remove irrelevant struct members from the setup request
* group members from the same IEs into structs
* set optional struct members IEs as pointers
* add and adopt enc/dec/cp/eq lib functions for single IEs
* add UP_TL_information_t struct with TEID and TL address info and adopt in stack
* use int instead of long for count types
* update the relevant copy/equality check utility functions
Extra:
* add a function to handle Security Information in RRC in the process
* add create_up_tl_info and adopt in unit tests
nFAPI: make 4-layer on 100MHz work
5G nFAPI headers specify 32 bits for the length field, so use it also
when segmenting messages. This should stabilize 4-layer MIMO operation
on 100MHz with nFAPI.
Deadlock avoidance in rfsimulator
This change introduces a countermeasure for deadlock in rfsimulator. The
deadlock happens when all entities are waiting for new data to come in,
and happens with 2+ clients, when a new client connects. I think this
issue is due to ordering of fullwrite calls, resulting in out-of-order
delivery of packets and eventually trashing the packets on the receiving
side. The out-of-order delivery warnings are printed just before the
system deadlocks but I have not found a better solution so far. The
workaround makes the server never lock up permanently by ignoring the
client failure to write on time after 10 tries.
This was tested locally for both UE as server and gNB as server and
works correctly, causing the deadlock to clear and the added log to be
printed several times when the deadlock is detected, after which the
system goes back to normal.
I have some gdb output of the executables during deadlock:
UE:
$7 = {conn_sock = 98, lastReceivedTS = 3226163740, headerMode = true, trashingPacket = false, th = {size = 13184, nbAnt = 1, timestamp = 3226150556, option_value = 0, option_flag = 0}, transferPtr = 0x7f6a500018a8 "\200\063", remainToTransfer = 24,
circularBufEnd = 0x7f6a503b3ac0 "", circularBuf = 0x7f6a501f1ac0, channel_model = 0x0}
(gdb) p t->buf[5]
$8 = {conn_sock = 97, lastReceivedTS = 0, headerMode = true, trashingPacket = false, th = {size = 0, nbAnt = 0, timestamp = 0, option_value = 0, option_flag = 0}, transferPtr = 0x7f6a50001900 "", remainToTransfer = 24, circularBufEnd = 0x7f6a50575ad0 "",
circularBuf = 0x7f6a503b3ad0, channel_model = 0x0}
nextRxTimestamp 3225937740
nsamps = 30720
gNB 1:
(gdb) p t->buf[0]
$4 = {conn_sock = 95, lastReceivedTS = 3226026876, headerMode = true, trashingPacket = false, th = {size = 1, nbAnt = 1, timestamp = 3226026875, option_value = 0, option_flag = 0},
transferPtr = 0x7f8dfc003ab8 "\001", remainToTransfer = 24, circularBufEnd = 0x7f8e1c3ff010 "", circularBuf = 0x7f8e1c23d010, channel_model = 0x0}
nextRxTimestamp 3225996956
gNB 2:
lastReceivedTS = 3226026875
$2 = {conn_sock = 95, lastReceivedTS = 3226026875, headerMode = true, trashingPacket = false, th = {size = 1, nbAnt = 1, timestamp = 3226026875, option_value = 0, option_flag = 0},
transferPtr = 0x744898003ab8 "\001", remainToTransfer = 24, circularBufEnd = 0x7448bc2e7010 "", circularBuf = 0x7448bc125010, channel_model = 0x0}
nextRxTimestamp 3226026875
As you can see all executables are in have_to_wait state.
38.463 sec. 8.2.3 says
> This procedure also re-initialises the E1AP UE-related contexts (if
> any) and erases all related signalling connections in the two nodes like
> a Reset procedure would do.
Hence, delete all contexts after reception of E1 Setup Response. This
minimizes a risk of receiving an E1 bearer setup req for an existing UE,
which currently leads to an assert [we trust the CU-CP does not send the
same UE ID twice, as we only "mirror" the existing UE ID].
* Without a valid 5G NAS security context:
* Send REGISTRATION REQUEST with cleartext IEs only.
* After activating a security context via Security Mode Control:
wrap the entire REGISTRATION REQUEST (with both non-cleartext and cleartext)
in a NAS message container IE, include it in SECURITY MODE COMPLETE
* With a valid 5G NAS security context:
* If non-cleartext IEs are needed, wrap the entire message in a NAS message container IE and cipher it.
* If only cleartext IEs are needed, send the message directly without the NAS message container IE.
* this commit is enabling the handling of non-cleartext IEs in the NAS Registration Request message
according to 24.501, 23.502
* send the full Registration Request message in the NAS Container of the SECURITY MODE COMPLETE
* send the non-cleartext IEs in the NAS container of the Registration Request
closes#881
* send integrity protected Initial NAS Message when UE in 5GMM-IDLE mode has valid current 5G NAS security context:
> According to 4.4.2.5 TS 24.501:
> when a UE in 5GMM-IDLE mode establishes a new NAS signalling connection and has a valid current 5G NAS
> security context, the UE shall transmit the initial NAS message integrity protected with the current 5G NAS security
> context and further protect this message as specified in subclause 4.4.6.
* set NAS key set identifier IE to "no key is available (UE to network)"
* previously set to 1 which has no impact
* set now to 111 in order to trigger new authentication
* See 9.11.3.32 of 3GPP TS 24.501
* Do 5GS Registration Type "mobility registration updating" when 5GMM state is De-registered
Make the same change as in parent commit, i.e., write the full 32-bit
segment size.
I could not test this, as we do not reach these rx_data.indication
length. It's based on the fix in the parent commit, and to avoid future
bad surprises.
The 5G nFAPI message length is 32bits. In particular tx_data.requests
can be longer than 64kB. When segmenting, we should correctly write the
message of the current segment (across all 32bits), because the
length would interpreted wrongly otherwise.
This fixes a bug in which tx_data.requests were discarded for 4-layer DL
MIMO on 100 MHz with this message:
P7 unpack message length is greater than the message buffer
Further, increase the type of various (segment-related) variables to 32
bits. Currently, the maximum segment size is sxt to 65000 bytes (and in
will likely remain, because the maximum UDP size is 65536);
nevertheless, increase it in case we will ever go beyond this.
See also commit dee68e6319 ("nFAPI: increase maximum segment size to
65000")
Simplify usage of the old segment decoding libraries with the slot coding interface
This MR transforms the segment coding libraries into slot coding
libraries by statically linking the adaptation layer and the segment
coding libraries.
Therefore they can be used directly in ldpctest which uses the segment
coding interface as well as in all the other PHY simulators and the NR
softmodem which use the slot coding interface.
It is not anymore needed to use the
--nrLDPC_coding_segment.segment_shlibversion
flag. Instead a segment coding library can be directly chosen with
--loader.ldpc.shlibversion
since it implements the slot coding interface.
Guido Casati