If I understood your question correctly then below is the answer of same.
When SCTP association gets established between two eNodeBs for X2-AP protocol, following things would be applicable.
- A single pair of stream identifier shall be reserved for the sole use of X2-AP non-UE associated signalling.
- At least one pair of stream identifier shall be reserved for UE-associated signalling. Few more pairs of stream identifiers should reserved.
- A single UE-associated signalling shall use one SCTP stream and the stream should not be changed during the communication of the UE-associated signalling.
3GPP TS 36.422