Can we establish a DRB without corresponding PDU session?

RAN
,
1

HI All,
Can we establish a DRB without corresponding PDU session?

2

In 5G not possible.

3

There is no DRB without a PDU.
PDU provides an anchor for all comms.
Yu attach to a PDN when you attach with network.
You can have communication without a DRB, but still you are attached to a network (CP optimisation in 4G was exactly this concept).

4

True, let me reframe my question:
If you have a QFI mapped to a DRB, can we release the QFI and not remove the DRB?

5

Someone more expert in 5G can comment…

But QFIs are probably managed by SDAP in gNB and DRB is E2E.
So in theory QFI can be dropped without DRB being deleted unless its last QFI mapped to that DRB.

6

Yeah…I would also think QFI can be dropped.
But can’t find spec reference for the same.