The function generateDRB() sets the value to 100ms but the function
rrc_gNB_process_NGAP_PDUSESSION_SETUP_REQ() sets it to 0ms.
So what happens is that the UE gets the value 100ms in the
RRC Reconfiguration but the gNB creates the PDCP entity with 0ms.
Let's create it with 100ms instead, to be aligned with how we configure
the UE.
And also avoid some PDCP warnings at runtime when some packets
are retransmitted but rejected because of the 0ms timer. This is
the warning:
[PDCP] discard NR PDU rcvd_count=68469, entity->rx_deliv 68481,sdu_in_list 0
This is just a hotfix. A real solution is to have the RB creation in
only one place. And we should also have those parameters configurable.
Work for later.
Multiple DUs host cells, whose cell ID cannot match (to identify them
uniquely). Hence, don't check for equality with CU, because otherwise,
we can never connect multiple DUs.
This is a workaround for a problem described in #706. In short, we
cannot reuse the cu_add/remove_f1_ue_data() functions if we are in an
integrated CU-UP/CP ("CU"), but then we can also not reliably use
different UE IDs in CU-UP and CU-CP (except if using even more hacks).
An assoc_id of 0 is used to mark UEs whose DU is "offline" (not
connected). In this patch, if a DU disconnects, we go through all UEs
and set their assoc_id to 0 if they belong to a UE that just went
offline.
This code printed BW masks (what is this) and number of MIMO layers. It
was dependent on the current DU, and only showed the information for the
current DU config (SCS, band). On DU disconnect, it leads to segfaults
to this dependency, and IMO is not useful in itself (it could rather be
printed when receiving the UE capabilities, for all bands etc.).
To allow to send F1 messages to multiple DUs from the CU, we need to
send these messages via different assoc_id (SCTP association ID,
basically akin to a file descriptor). Currently, the assoc_id is stored
in a context at the F1 module and retrieved in
f1ap_itti_send_sctp_data_req().
To facilitate a later change towards indicating (from the RRC) to which
assoc_id (hence, DU) to send a message, we refactor all
CU_send_*()/DU_send_*() functions to take the assoc_id as a parameter to
which to send messages. In this commit, we then pass the assoc_id from
the context. A later commit changes this (at the CU) to pass the
assoc_id from the message to be sent.
Previous to this commit, the CU creates an F1 instance and initializes
GTP after a successful connection establishment, and tears the F1
instance down after the DU disconnects. This does not work when trying
to connect multiple DUs, or have them reconnect, as e.g., GTP
re-initialization fails (socket already bound).
This commit makes the CU F1 instance creation and GTP init at CU task
init (only once), and also frees the F1 instance only after the CU task
exits, which is at termination of the application, typically.
The DU UE capability printing depends on data on SCS and band, which
currently is only stored with the DU. To avoid any assert, we check
that the DU is present. A follow-up commit will rework this.
Robert Schmidt