SCTP Multi-Streaming Feature

The term “Stream” in SCTP is derived from the multi-streaming function provided by SCTP. The feature also helps in dividing the data into multiple streams that do not have a limitation to be delivered sequentially. This is also effective in case there is a loss of information in a specific stream the data can be delivered through other streams. This helps in avoiding unwanted delay because of the sequencing (which as a property of the TCP).

This property of SCTP is very helpful in telecom signalling which does not require sequencing.
Another example of possible use of multi-streaming is the delivery of multimedia documents, such as a web page, when done over a single session. Since multimedia documents consist of objects of different sizes and types, multi-streaming allows transport of these components to be partially ordered rather than strictly ordered, and may result
in improved user perception of transport.
SCTP accomplishes multi-streaming by creating independence between data transmission and data delivery. In particular, each payload DATA “chunk” in the protocol uses two sets of sequence numbers, a Transmission Sequence Number that governs the transmission of messages and the detection of message loss, and the Stream ID/Stream
Sequence Number pair, which is used to determine the sequence of delivery of received data.

If a message is received within the affected stream, there will be a corresponding gap in the Stream Sequence Number, while messages from other streams will not show a gap. The receiver can therefore continue to deliver messages to the unaffected streams while buffering messages in the affected stream until retransmission occurs.