Stream Control Transmission Protocol

  • RFC 2960 (2000)
  • RFC 4960 (2007)

The Stream Control Transmission Protocol ( SCTP ​​) is a reliable, connection-oriented network protocol. It belongs to the transport layer and is based on a potentially unreliable connectionless packet service on.

Features and Functions

It was proposed by the Internet Engineering Task Force ( IETF) as a new transport protocol, and published in October 2000 in the standard document RFC 2960 and extended by RFC 4960 in September 2007. An introduction can also be found in RFC 3286th The committee in charge at the IETF is the Working Group Signaling Transport, short SIGTRAN.

As the transport protocol SCTP ​​is on the same level of the TCP / IP reference model, such as TCP and UDP ( layer 4 of the OSI model ).

SCTP implements the concept of an association: Here a connection is established, in which a plurality of message data streams to be transported in order- preserving ( among themselves but potentially non- order- preserving). In addition, individual, for example, urgent, datagrams can be sent separately and out of order, which thereby may " overtake " the in-order data streams.

SCTP also knows multi- streaming and multi-homing ( a host with multiple valid IP addresses ). There are heartbeats used to test active connection to demolition.

Unlike TCP, SCTP ​​shows itself resistant to SYN flood, a denial-of- service attack, in which half-open connections through the server's resources are depleted. It uses a so-called four-way handshake. In this case, the server stores in a connection request (INIT packet) no state information, but sends it in the form of a cookie (INIT - ACK packet ) to the client. The client needs the cookie in its response ( COOKIE- ECHO packet ) insert and is therefore recognized by the server as the right to establish the connection, what this confirms it ( COOKIE- ACK packet ). A similar process is also possible with TCP, see SYN cookies.

Originally SCTP ​​has been defined as the transport protocol to be able to transmit signaling messages ( SS7) from telephone networks via IP networks. In the development of particular stood the reliability of the protocol in the foreground. SCTP is also suitable for other applications, as it combines the advantages of TCP and UDP. An important application is built on SCTP ​​Reliable Server Pooling ( RSerPool ).

SCTP is used for flow and congestion control similar algorithms such as TCP, thus behaves in a mixed network ( SCTP ​​and TCP) neutral. ( PDF)

Specifications

  • Stream Control Transmission Protocol RFC 2960 (2000)
  • Stream Control Transmission Protocol RFC 4960 (2007)
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