Are CU connected to DU of each cell id or is it common F1 link?

RAN
,
1

Hi Experts,
Are CU connected to DU of each cell id or is it common F1 link?

2

CU to DU f1 link.
1 CU can support multiple DU.
And 1 DU can be connected to multiple cells and gNB.

3

Ok, so CU to DU entire is a link.
Not a particular cell id of Du.
I have seen one cell failing to target cell in endc-prep of DU and remaining target are fine.
So what can be the reason.
Failing to one target cell.
Intra gNodeB.