In 5G PDU session, can 1 DRB be linked to mutiple QFI flows?
Is it possible?
I haven’t checked 5G much, but in 4G you can have upto 16 Traffic Flows per Bearer - which is more or less equivalent to QFIs as per your post.
So answer is Yes.
Thanks. I am trying to think how does it help.
Let’s say data is to be sent in the uplink via DRB1, now if both QFI 1 and 2 are mapped to it, how does the UE decide which QFI to send it to?
IP Filters. UE is told about range of IPs and which Bearer to use for IP range. If destination IP falls in certain range, UE checks and use appropriate parameters and bearer
Usually this is done to keep IP traffic separate or segregated. Overall traffic is treated same way through the network (because rest of quality parameters same)
Imagine 2 Organizations want to provide FTP service. Network may assign 5QI- 10 for this and within this give UE 2 separate IP ranges. UE will use same bearer but network will route traffic to different FTP destination
Makes sense.
So in my examples, I would think SDAP is the one which should decide whether it goes on QFI1 or 2.
But in the RRC reconfigure msg where the mapping of QFI and DRBs are given, I would not find any filter which tells SDAP how to map on different QFIs.
In 4G initial filters come with Attach and then rest with individual bearers.
PDU session consist of multiple QoS flow sdap mapped this to DRB.
In my view, QFI mapped to QoS flow by SMF node.
Well, my only concern was how to differentiate between which data needs to go on qfi1 or qfi2, since they both are mapped to single drb.
Ok I got it. Need to check if is it possible to map on single drb. Good query.
Currently Huawei RAN do not have SDAP layer.
I think other vendors also don’t have too…
SDAP only for SA architecture.
Yes, only SA, sdap higher than pdcp.
But introduced in 3gpp r16, now huawei RAN just follow R15.
I think it’s in rel 15.
Sdap is.mandatory if you have 5G Core.
For NSA, you don’t need SDAP.
I agree but SA is part of rel15.
SDAP required with option 2, 5, 4, 4a, 7, 7a.
In above all options 5G CORE required.
Yes, I agree.
Finally got my ans. 
From 38.324.
One or more QoS flows may be mapped onto one DRB. One QoS flow is mapped onto only one DRB at a time in the UL.
Thanks. There is limit to these as well.
In 4G it is 16 per bearer and usually up to 8 bearers per UE.