What is SCTP?


SCTP represents Stream Control Transmission Protocol. It is a new reliable, message-oriented transport layer protocol. It is generally created for Internet applications that have currently been introduced. These new applications include IUA (ISDN over IP), M2UA and M3UA (telephony signaling), H.248 (media gateway control), H.323 (IP telephony), and SIP (IP telephony), etc.

SCTP connects the characteristics of UDP and TCP. It is a reliable message-oriented protocol. It can maintain the message boundaries and simultaneously detects lost information, duplicate information, and out-of-order information. It also has congestion control and flow control structure.

Features of SCTP

There are various features of SCTP which are as follows −

  • Transmission Sequence Number

    The group of data in TCP is a byte. Data sent in TCP is controlled by numbering bytes by utilizing a sequence number. The unit of data in SCTP is a DATA block that can or cannot have a one-to-one relationship with the message appearing from the process due to fragmentation.

  • Stream Identifier

    In TCP, there should be one stream in every connection. In SCTP, there can be multiple streams in each association. Each stream in SCTP is required to be identified by using a stream identifier (SI).

    Each data block should carry the SI in its header so that when it appears at the destination, it can be correctly located in its stream. The 51 is a 16-bit number beginning from 0.

  • Stream Sequence Number

    When a data block appears at the destination SCTP, it is delivered to the suitable stream and in the accurate order. This represents that further an SI, SCTP defines each data block in each stream with a stream sequence number (SSN).
  • Packets

    In TCP, a segment gives data and control information. Data is carried as a set of bytes; control data is represented by six control flags in the header. The design of SCTP is completely different such as data are carried as data blocks, control data is carried as control blocks.

  • Flow Control

    Like TCP, SCTP executes flow control to prevent overwhelming the receiver.

  • Error Control

    Like TCP, SCTP executes error control to support reliability. TSN numbers and acknowledgment numbers are used for error control.

  • Congestion Control

    Like TCP, SCTP executes congestion control to decide how many data blocks can be inserted into the network.

Updated on: 19-Nov-2021

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