When an eNodeB setups X2 connection with its neighbor eNodeBs, following information gets exchanged.
X2 SETUP REQUEST message from eNB1 to eNB2:
- Global eNodeB ID of the sending eNodeB
- List of Serving Cell Information (an eNodeB can support up to 256 cells)
- Neighbor Cells Information (an eNodeB can support up to 512 cells)
- List of MME Pool Ids (an eNodeB can have connection with up to 16 MME pools)
--> Serving Cell Information contains information (PCI, ECGI, TAC, list of broad casted PLMNs and running mode (FDD mode/TDD mode) of the cell.
---> Neighbor Cell Information (PCI, ECGI, EARFCN )
---> MME Pool Id consists of PLMN + MME Group Id
X2 SETUP RESPONSE message from eNB2 to eNB1: eNB2 also shares the similar information with the eNB1.
Reference : TS 36.423