SCTP

The Stream Control Transmission Protocol (SCTP) uses a 32-bit checksum in the common header of each packet to provide some level of data integrity. If another method used by SCTP already provides the same or a higher level of data integrity, computing this checksum does not provide any additional protection but does consume computing resources.

This document provides a simple extension allowing SCTP to save these computing resources by using zero as the checksum in a backwards-compatible way. It also defines how this feature can be used when SCTP packets are encapsulated in Datagram Transport Layer Security (DTLS) packets.

This document describes the Stream Control Transmission Protocol (SCTP) and obsoletes RFC 4960. It incorporates the specification of the chunk flags registry from RFC 6096 and the specification of the I bit of DATA chunks from RFC 7053. Therefore, RFCs 6096 and 7053 are also obsoleted by this document. In addition, RFCs 4460 and 8540, which describe errata for SCTP, are obsoleted by this document.

SCTP was originally designed to transport Public Switched Telephone Network (PSTN) signaling messages over IP networks. It is also suited to be used for other applications, for example, WebRTC.

SCTP is a reliable transport protocol operating on top of a connectionless packet network, such as IP. It offers the following services to its users:

The design of SCTP includes appropriate congestion avoidance behavior and resistance to flooding and masquerade attacks.

The Stream Control Transmission Protocol (SCTP) is a transport protocol used to establish associations between two endpoints. RFC 8261 specifies how SCTP can be used on top of the Datagram Transport Layer Security (DTLS) protocol, which is referred to as SCTP-over-DTLS.

This specification defines the following new Session Description Protocol (SDP) protocol identifiers (proto values): "UDP/DTLS/SCTP" and "TCP/DTLS/SCTP". This specification also specifies how to use the new proto values with the SDP offer/answer mechanism for negotiating SCTP-over-DTLS associations.

This document defines how to use the WebRTC data channel mechanism to realize a data channel, referred to as a Controlling Multiple Streams for Telepresence (CLUE) data channel, for transporting CLUE protocol messages between two CLUE entities.

This document specifies Datagram Packetization Layer Path MTU Discovery (DPLPMTUD). This is a robust method for Path MTU Discovery (PMTUD) for datagram Packetization Layers (PLs). It allows a PL, or a datagram application that uses a PL, to discover whether a network path can support the current size of datagram. This can be used to detect and reduce the message size when a sender encounters a packet black hole. It can also probe a network path to discover whether the maximum packet size can be increased. This provides functionality for datagram transports that is equivalent to the PLPMTUD specification for TCP, specified in RFC 4821, which it updates. It also updates the UDP Usage Guidelines to refer to this method for use with UDP datagrams and updates SCTP.

The document provides implementation notes for incorporating Datagram PMTUD into IETF datagram transports or applications that use datagram transports.

This specification updates RFC 4960, RFC 4821, RFC 6951, RFC 8085, and RFC 8261.

The Stream Control Transmission Protocol (SCTP) is a message-oriented transport protocol supporting arbitrarily large user messages. This document adds a new chunk to SCTP for carrying payload data. This allows a sender to interleave different user messages that would otherwise result in head-of-line blocking at the sender. The interleaving of user messages is required for WebRTC data channels.

Whenever an SCTP sender is allowed to send user data, it may choose from multiple outgoing SCTP streams. Multiple ways for performing this selection, called stream schedulers, are defined in this document. A stream scheduler can choose to either implement, or not implement, user message interleaving.

The Stream Control Transmission Protocol (SCTP) is a transport protocol originally defined to run on top of the network protocols IPv4 or IPv6. This document specifies how SCTP can be used on top of the Datagram Transport Layer Security (DTLS) protocol. Using the encapsulation method described in this document, SCTP is unaware of the protocols being used below DTLS; hence, explicit IP addresses cannot be used in the SCTP control chunks. As a consequence, the SCTP associations carried over DTLS can only be single-homed.

The goal of this document is to describe the potential benefits of applications using a transport that enables Explicit Congestion Notification (ECN). The document outlines the principal gains in terms of increased throughput, reduced delay, and other benefits when ECN is used over a network path that includes equipment that supports Congestion Experienced (CE) marking. It also discusses challenges for successful deployment of ECN. It does not propose new algorithms to use ECN nor does it describe the details of implementation of ECN in endpoint devices (Internet hosts), routers, or other network devices.

The Stream Control Transmission Protocol (SCTP) supports multihoming. However, when the failover operation specified in RFC 4960 is followed, there can be significant delay and performance degradation in the data transfer path failover. This document specifies a quick failover algorithm and introduces the SCTP Potentially Failed (SCTP-PF) destination state in SCTP Path Management.

This document also specifies a dormant state operation of SCTP that is required to be followed by an SCTP-PF implementation, but it may equally well be applied by a standard SCTP implementation, as described in RFC 4960.

Additionally, this document introduces an alternative switchback operation mode called "Primary Path Switchover" that will be beneficial in certain situations. This mode of operation applies to both a standard SCTP implementation and an SCTP-PF implementation.

The procedures defined in the document require only minimal modifications to the specification in RFC 4960. The procedures are sender-side only and do not impact the SCTP receiver.

This document describes a modified sender-side algorithm for managing the TCP and Stream Control Transmission Protocol (SCTP) retransmission timers that provides faster loss recovery when there is a small amount of outstanding data for a connection. The modification, RTO Restart (RTOR), allows the transport to restart its retransmission timer using a smaller timeout duration, so that the effective retransmission timeout (RTO) becomes more aggressive in situations where fast retransmit cannot be used. This enables faster loss detection and recovery for connections that are short lived or application limited.

This document provides recommendations to designers of application and service protocols on how to use the transport protocol port number space and when to request a port assignment from IANA. It provides designer guidance to requesters or users of port numbers on how to interact with IANA using the processes defined in RFC 6335; thus, this document complements (but does not update) that document.

This document defines two additional policies for the Partially Reliable Stream Control Transmission Protocol (PR-SCTP) extension. These policies allow limitation of the number of retransmissions and prioritization of user messages for more efficient usage of the send buffer.

This document describes a simple method of encapsulating Stream Control Transmission Protocol (SCTP) packets into UDP packets and its limitations. This allows the usage of SCTP in networks with legacy NATs that do not support SCTP. It can also be used to implement SCTP on hosts without directly accessing the IP layer, for example, implementing it as part of the application without requiring special privileges.

Please note that this document only describes the functionality required within an SCTP stack to add on UDP encapsulation, providing only those mechanisms for two end-hosts to communicate with each other over UDP ports. In particular, it does not provide mechanisms to determine whether UDP encapsulation is being used by the peer, nor the mechanisms for determining which remote UDP port number can be used. These functions are out of scope for this document.

This document covers only end-hosts and not tunneling (egress or ingress) endpoints.

This document formally deprecates the use of ICMP Source Quench messages by transport protocols, formally updating RFC 792, RFC 1122, and RFC 1812. [STANDARDS-TRACK]

This document specifies an extension to the specifications in RFC 5101, IP Flow Information Export (IPFIX), when using the Partial Reliability extension of SCTP (PR-SCTP, Partial Reliability Stream Control Transmission Protocol).

When implemented at both the Exporting Process and Collecting Process, this method offers several advantages, such as the ability to calculate Data Record losses for PR-SCTP per Template, immediate export of Template Withdrawal Messages, immediate reuse of Template IDs within an SCTP stream, reduced likelihood of Data Record loss, and reduced demands on the Collecting Process. When implemented in only the Collecting Process or Exporting Process, then normal IPFIX behavior will be seen without all of the additional benefits. [STANDARDS-TRACK]

Many applications that use the Stream Control Transmission Protocol (SCTP) want the ability to "reset" a stream. The intention of resetting a stream is to set the numbering sequence of the stream back to 'zero' with a corresponding notification to the application layer that the reset has been performed. Applications requiring this feature want it so that they can "reuse" streams for different purposes but still utilize the stream sequence number so that the application can track the message flows. Thus, without this feature, a new use of an old stream would result in message numbers greater than expected, unless there is a protocol mechanism to "reset the streams back to zero". This document also includes methods for resetting the transmission sequence numbers, adding additional streams, and resetting all stream sequence numbers. [STANDARDS-TRACK]

This document describes a mapping of the Stream Control Transmission Protocol (SCTP) into a sockets API. The benefits of this mapping include compatibility for TCP applications, access to new SCTP features, and a consolidated error and event notification scheme. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document describes the usage of the Datagram Transport Layer Security (DTLS) protocol over the Stream Control Transmission Protocol (SCTP).

DTLS over SCTP provides communications privacy for applications that use SCTP as their transport protocol and allows client/server applications to communicate in a way that is designed to prevent eavesdropping and detect tampering or message forgery.

Applications using DTLS over SCTP can use almost all transport features provided by SCTP and its extensions. [STANDARDS-TRACK]

The General Internet Signaling Transport (GIST) protocol currently uses TCP or Transport Layer Security (TLS) over TCP for Connection mode operation. This document describes the usage of GIST over the Stream Control Transmission Protocol (SCTP) and Datagram Transport Layer Security (DTLS). This document defines an Experimental Protocol for the Internet community.

Forwarding and Control Element Separation (ForCES) defines an architectural framework and associated protocols to standardize information exchange between the control plane and the forwarding plane in a ForCES network element (ForCES NE). RFC 3654 has defined the ForCES requirements, and RFC 3746 has defined the ForCES framework.

This document is an implementation report for the ForCES Protocol, Model, and the Stream Control Transmission Protocol-based Transport Mapping Layer (SCTP TML) documents, and includes a report on interoperability testing and the current state of ForCES implementations. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document enables a pair of communicating proxies to reuse a congestion-controlled connection between themselves for sending requests in the forwards and backwards direction. Because the connection is essentially aliased for requests going in the backwards direction, reuse is predicated upon both the communicating endpoints authenticating themselves using X.509 certificates through Transport Layer Security (TLS). For this reason, we only consider connection reuse for TLS over TCP and TLS over Stream Control Transmission Protocol (SCTP). This document also provides guidelines on connection reuse and virtual SIP servers and the interaction of connection reuse and DNS SRV lookups in SIP. [STANDARDS-TRACK]

This document proposes a new mechanism for TCP and Stream Control Transmission Protocol (SCTP) that can be used to recover lost segments when a connection's congestion window is small. The "Early Retransmit" mechanism allows the transport to reduce, in certain special circumstances, the number of duplicate acknowledgments required to trigger a fast retransmission. This allows the transport to use fast retransmit to recover segment losses that would otherwise require a lengthy retransmission timeout. [STANDARDS-TRACK]

This document defines the SCTP-based TML (Transport Mapping Layer) for the ForCES (Forwarding and Control Element Separation) protocol. It explains the rationale for choosing the SCTP (Stream Control Transmission Protocol) and also describes how this TML addresses all the requirements required by and the ForCES protocol. [STANDARDS TRACK]

This document specifies an adaptation layer to provide a Lower Layer Protocol (LLP) service for Direct Data Placement (DDP) using the Stream Control Transmission Protocol (SCTP). [STANDARDS-TRACK]

A local host may have multiple points of attachment to the Internet, giving it a degree of fault tolerance from hardware failures. Stream Control Transmission Protocol (SCTP) (RFC 4960) was developed to take full advantage of such a multi-homed host to provide a fast failover and association survivability in the face of such hardware failures. This document describes an extension to SCTP that will allow an SCTP stack to dynamically add an IP address to an SCTP association, dynamically delete an IP address from an SCTP association, and to request to set the primary address the peer will use when sending to an endpoint. [STANDARDS-TRACK]

This document describes certain security threats to SCTP. It also describes ways to mitigate these threats, in particular by using techniques from the SCTP Specification Errata and Issues memo (RFC 4460). These techniques are included in RFC 4960, which obsoletes RFC 2960. It is hoped that this information will provide some useful background information for many of the newest requirements spelled out in the SCTP Specification Errata and Issues and included in RFC 4960. This memo provides information for the Internet community.

This document describes a new chunk type, several parameters, and procedures for the Stream Control Transmission Protocol (SCTP). This new chunk type can be used to authenticate SCTP chunks by using shared keys between the sender and receiver. The new parameters are used to establish the shared keys. [STANDARDS-TRACK]

This document defines a padding chunk and a padding parameter and describes the required receiver side procedures. The padding chunk is used to pad a Stream Control Transmission Protocol (SCTP) packet to an arbitrary size. The padding parameter is used to pad an SCTP INIT chunk to an arbitrary size. [STANDARDS-TRACK]

This memo defines a protocol for supporting the transport of any SS7 MTP3-User signalling (e.g., ISUP and SCCP messages) over IP using the services of the Stream Control Transmission Protocol. Also, provision is made for protocol elements that enable a seamless operation of the MTP3-User peers in the SS7 and IP domains. This protocol would be used between a Signalling Gateway (SG) and a Media Gateway Controller (MGC) or IP-resident Database, or between two IP-based applications. It is assumed that the SG receives SS7 signalling over a standard SS7 interface using the SS7 Message Transfer Part (MTP) to provide transport. This document obsoletes RFC 3332. [STANDARDS-TRACK]

This document describes the applicability of the several protocols developed under the signalling transport framework. A description of the main issues regarding the use of the Stream Control Transmission Protocol (SCTP) and an explanation of each adaptation layer for transport of telephony signalling information over IP infrastructure are given. This memo provides information for the Internet community.

This document defines a protocol for backhauling of Integrated Services Digital Network (ISDN) Q.921 User messages over IP using the Stream Control Transmission Protocol (SCTP). This protocol would be used between a Signaling Gateway (SG) and Media Gateway Controller (MGC). It is assumed that the SG receives ISDN signaling over a standard ISDN interface.

This document obsoletes RFC 3057. [STANDARDS-TRACK]

This document specifies a mechanism for usage of SCTP (the Stream Control Transmission Protocol) as the transport mechanism between SIP (Session Initiation Protocol) entities. SCTP is a new protocol that provides several features that may prove beneficial for transport between SIP entities that exchange a large amount of messages, including gateways and proxies. As SIP is transport-independent, support of SCTP is a relatively straightforward process, nearly identical to support for TCP. [STANDARDS-TRACK]

Spurious retransmission timeouts cause suboptimal TCP performance because they often result in unnecessary retransmission of the last window of data. This document describes the F-RTO detection algorithm for detecting spurious TCP retransmission timeouts. F-RTO is a TCP sender-only algorithm that does not require any TCP options to operate. After retransmitting the first unacknowledged segment triggered by a timeout, the F-RTO algorithm of the TCP sender monitors the incoming acknowledgments to determine whether the timeout was spurious. It then decides whether to send new segments or retransmit unacknowledged segments. The algorithm effectively helps to avoid additional unnecessary retransmissions and thereby improves TCP performance in the case of a spurious timeout. The F-RTO algorithm can also be applied to the Stream Control Transmission Protocol (SCTP). This memo defines an Experimental Protocol for the Internet community.

This document defines a protocol for the transport of any Signalling Connection Control Part-User signalling over IP using the Stream Control Transmission Protocol. The protocol is designed to be modular and symmetric, to allow it to work in diverse architectures, such as a Signalling Gateway to IP Signalling Endpoint architecture as well as a peer-to-peer IP Signalling Endpoint architecture. [STANDARDS-TRACK]

The Stream Control Transmission Protocol (SCTP) is a reliable transport protocol operating on top of a connectionless packet network such as IP. It is designed to transport public switched telephone network (PSTN) signaling messages over the connectionless packet network, but is capable of broader applications.

This memo defines the Management Information Base (MIB) module which describes the minimum set of objects needed to manage the implementation of the SCTP. [STANDARDS-TRACK]

This document defines a mechanism for the backhauling of V5.2 messages over IP using the Stream Control Transmission Protocol (SCTP). This protocol may be used between a Signaling Gateway (SG) and a Media Gateway controller (MGC). It is assumed that the SG receives V5.2 signaling over a standard V5.2 interface. This document builds on the ISDN User Adaptation Layer Protocol (RFC 3057). It defines all necessary extensions to the IUA Protocol needed for the V5UA protocol implementation. [STANDARDS-TRACK]

This memo describes an extension to the Stream Control Transmission Protocol (SCTP) that allows an SCTP endpoint to signal to its peer that it should move the cumulative ack point forward. When both sides of an SCTP association support this extension, it can be used by an SCTP implementation to provide partially reliable data transmission service to an upper layer protocol. This memo describes the protocol extensions, which consist of a new parameter for INIT and INIT ACK, and a new FORWARD TSN chunk type, and provides one example of a partially reliable service that can be provided to the upper layer via this mechanism. [STANDARDS-TRACK]

TCP and Stream Control Transmission Protocol (SCTP) provide notification of duplicate segment receipt through Duplicate Selective Acknowledgement (DSACKs) and Duplicate Transmission Sequence Number (TSN) notification, respectively. This document presents conservative methods of using this information to identify unnecessary retransmissions for various applications. This memo defines an Experimental Protocol for the Internet community.

This document describes functional requirements for IPsec (RFC 2401) and Internet Key Exchange (IKE) (RFC 2409) to facilitate their use in securing SCTP (RFC 2960) traffic. [STANDARDS-TRACK]

This document describes the usage of the Transport Layer Security (TLS) protocol, as defined in RFC 2246, over the Stream Control Transmission Protocol (SCTP), as defined in RFC 2960 and RFC 3309. The user of TLS can take advantage of the features provided by SCTP, namely the support of multiple streams to avoid head of line blocking and the support of multi-homing to provide network level fault tolerance. Additionally, discussions of extensions of SCTP are also supported, meaning especially the support of dynamic reconfiguration of IP- addresses. [STANDARDS-TRACK]

This Internet Draft defines a protocol for backhauling of SS7 MTP2

User signaling messages over IP using the Stream Control

Transmission Protocol (SCTP). This protocol would be used between a

Signaling Gateway (SG) and Media Gateway Controller (MGC). It is

assumed that the SG receives SS7 signaling over a standard SS7

interface using the SS7 Message Transfer Part (MTP) to provide

transport. The Signaling Gateway would act as a Signaling Link

Terminal.

This document provides a high level introduction to the capabilities supported by the Stream Control Transmission Protocol (SCTP). It is intended as a guide for potential users of SCTP as a general purpose transport protocol. This memo provides information for the Internet community.

This document describes the applicability of the Stream Control Transmission Protocol (SCTP). It also contrasts SCTP with the two dominant transport protocols, User Datagram Protocol (UDP) & Transmission Control Protocol (TCP), and gives some guidelines for when best to use SCTP and when not best to use SCTP. This memo provides information for the Internet community.