Phy-RF interface.
Why option 7.2 prefer over option 8 for O-RAN?
What I understand these are interfaces for O-RAN.
In O- RAN any change in interface between O-CU and O-DU or its only F1.
These are layer splits not interfaces.
Ok thanks.
I am finding option 2, option 8, option 7.2.
Are these interfaces only?
Actually getting mixed with option 2 for SA part where gnb connected to core network.
Please help to tell understanding correct or not:
Option 2 means split between cu and du.
Option 7.2, 8 split between du and ru.
Interface wise between option cu and du its F1 between DU and RU its ecpri for O-RAN.
Yes many times I also get confused .
I found a post may be helpful for you:
Interface wise we can divide architecture as backhual, midhaul and formthaul.
Yes correct. F1 I know, E1, E2, A1.
Between ru and du is there any name of interface or we call it cpri or ecpri.
F1 is basically midhual.
Ru du is cpri.
Actually between ru and du interface name:
Ok so its cpri only.
For O-RAN its ecpri.
Cpri and ecpri difference is data rate support and some additional c&m features.
Yes ecpri upto 25 Gig.
Cpri low rate.
I seen in one of keysight doc option 8 having issue as physical layer inside DU only so not use for O-RAN.
Option 7.2 preferred as of now.
Option 8 does not have phy inside ru.
Option 7 put lower phy inside ru.
Yes high phy inside du and low phy inside ru.
Option 8 is traditional what is already deployed in fields.
Yes agree need to be careful so option for 5G architecture not mixed with O-RAN.
Issue I faced before now clear. 
How I remember these one is deployment architecture like sa and nsa secondly layer split architecture like option 7.2, option 2.
Very nice its perfect.
So let me summarize:
Architecture: option 2,5 for SA
Option 3,3a,3x,4,4a,7,7a for NSA
Now option 7.2,8,2 split name in O-RAN
Please correct if wrong.
Prefect but one thing in mind these layer spilts are defined by 3gpp and O-RAN is re-using it.
Ok is it I find work group like 1 to 9 for O-RAN so these split not part of these work groups.
One additional info:
In the case of split 8 most vendors use ethernet over CPRI for management (usually proprietary)
In the case o 7.2 is eCPRI over ethernet, and add the Sync portion to the frame.
Splits 1, 2, 3, 4, 5, 6, 7, 7.1, 7.2, 7.3, 8 are all 3GPP standard.
O-RAN specify a new one between 7.2 and 7.1, knows as 7.2x (O-RAN Open Fronthaul) that divides the low-phy between RE mapping and Beamforming port mapping.
In the case of Split 8, The RRU don’t process low-phy, it just received I/Q in the CPRI (Master-Slave) link.
I am not O-RAN expert, but here is my view as of now.
3GPP has standardize higher layer split as F1 interface.
But lower layer split has left to the vendor.
Now there are multiple options.
Option 8 is to keep entire physical layer in DU and only radio part in RU.
Since precoding, beamforming comes in DU part, BW required for CPRI/eCPRI is very high around more than 150 Gbps.
Option 7.2 keeps lower physcal layer in RU and higher PHY layer in DU.
So bandwidth requirement of CPRI comes down to around 25 Gbps.
Hence option 7.2 is preferred.