DCCP

Datagram Congestion Control Protocol (DCCP) communications, as defined in RFC 4340, are inherently restricted to a single path per connection, despite the availability of multiple network paths between peers. The ability to utilize multiple paths simultaneously for a DCCP session can enhance network resource utilization, improve throughput, and increase resilience to network failures, ultimately enhancing the user experience.

Use cases for Multipath DCCP (MP-DCCP) include mobile devices (e.g., handsets and vehicles) and residential home gateways that maintain simultaneous connections to distinct network types such as cellular and Wireless Local Area Networks (WLANs) or cellular and fixed access networks. Compared to existing multipath transport protocols, such as Multipath TCP (MPTCP), MP-DCCP is particularly suited for latency-sensitive applications with varying requirements for reliability and in-order delivery.

This document specifies a set of protocol extensions to DCCP that enable multipath operations. These extensions maintain the same service model as DCCP while introducing mechanisms to establish and utilize multiple concurrent DCCP flows across different network paths.

This document describes, surveys, and classifies the protocol mechanisms provided by existing IETF protocols, as background for determining a common set of transport services. It examines the Transmission Control Protocol (TCP), Multipath TCP, the Stream Control Transmission Protocol (SCTP), the User Datagram Protocol (UDP), UDP-Lite, the Datagram Congestion Control Protocol (DCCP), the Internet Control Message Protocol (ICMP), the Real-Time Transport Protocol (RTP), File Delivery over Unidirectional Transport / Asynchronous Layered Coding (FLUTE/ALC) for Reliable Multicast, NACK- Oriented Reliable Multicast (NORM), Transport Layer Security (TLS), Datagram TLS (DTLS), and the Hypertext Transport Protocol (HTTP), when HTTP is used as a pseudotransport. This survey provides background for the definition of transport services within the TAPS working group.

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 specifies an alternative encapsulation of the Datagram Congestion Control Protocol (DCCP), referred to as DCCP-UDP. This encapsulation allows DCCP to be carried through the current generation of Network Address Translation (NAT) middleboxes without modification of those middleboxes. This document also updates the Session Description Protocol (SDP) information for DCCP defined in RFC 5762. [STANDARDS-TRACK]

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 update to the round-trip time (RTT) estimation algorithm used for TFRC (TCP-Friendly Rate Control) congestion control by the Datagram Congestion Control Protocol (DCCP). It updates specifications for the CCID-3 and CCID-4 Congestion Control IDs of DCCP.

The update addresses parameter-estimation problems occurring with TFRC-based DCCP congestion control. It uses a recommendation made in the original TFRC specification to avoid the inherent problems of receiver-based RTT sampling, by utilising higher-accuracy RTT samples already available at the sender.

It is integrated into the feature set of DCCP as an end-to-end negotiable extension. [STANDARDS-TRACK]

The Real-time Transport Protocol (RTP) is a widely used transport for real-time multimedia on IP networks. The Datagram Congestion Control Protocol (DCCP) is a transport protocol that provides desirable services for real-time applications. This memo specifies a mapping of RTP onto DCCP, along with associated signalling, such that real- time applications can make use of the services provided by DCCP. [STANDARDS-TRACK]

This document describes the usage of Service Codes by the Datagram Congestion Control Protocol, RFC 4340. It motivates the setting of a Service Code by applications. Service Codes provide a method to identify the intended service/application to process a DCCP connection request. This provides improved flexibility in the use and assignment of port numbers for connection multiplexing. The use of a DCCP Service Code can also enable more explicit coordination of services with middleboxes (e.g., network address translators and firewalls). This document updates the specification provided in RFC 4340. [STANDARDS-TRACK]

This document specifies an update to the Datagram Congestion Control Protocol (DCCP), a connection-oriented and datagram-based transport protocol. The update adds support for the DCCP-Listen packet. This assists DCCP applications to communicate through middleboxes (e.g., a Network Address Port Translator or a DCCP server behind a firewall), where peering endpoints need to initiate communication in a near- simultaneous manner to establish necessary middlebox state. [STANDARDS-TRACK]

This document defines a set of requirements for NATs handling the Datagram Congestion Control Protocol (DCCP). These requirements allow DCCP applications, such as streaming applications, to operate consistently, and they are very similar to the TCP requirements for NATs, which have already been published by the IETF. Ensuring that NATs meet this set of requirements will greatly increase the likelihood that applications using DCCP will function properly. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.

This document specifies the use of the Quick-Start mechanism by the Datagram Congestion Control Protocol (DCCP). DCCP is a transport protocol that allows the transmission of congestion-controlled, unreliable datagrams. DCCP is intended for applications such as streaming media, Internet telephony, and online games. In DCCP, an application has a choice of congestion control mechanisms, each specified by a Congestion Control Identifier (CCID). This document specifies general procedures applicable to all DCCP CCIDs and specific procedures for the use of Quick-Start with DCCP CCID 2, CCID 3, and CCID 4. Quick-Start enables a DCCP sender to cooperate with Quick-Start routers along the end-to-end path to determine an allowed sending rate at the start of a connection and, at times, in the middle of a DCCP connection (e.g., after an idle or application- limited period). The present specification is provided for use in controlled environments, and not as a mechanism that would be intended or appropriate for ubiquitous deployment in the global Internet. This memo defines an Experimental Protocol for the Internet community.

This document specifies a profile for Congestion Control Identifier 4, the small-packet variant of TCP-Friendly Rate Control (TFRC), in the Datagram Congestion Control Protocol (DCCP). CCID 4 is for experimental use, and uses TFRC-SP (RFC 4828), a variant of TFRC designed for applications that send small packets. CCID 4 is considered experimental because TFRC-SP is itself experimental, and is not proposed for widespread deployment in the global Internet at this time. The goal for TFRC-SP is to achieve roughly the same bandwidth in bits per second (bps) as a TCP flow using packets of up to 1500 bytes but experiencing the same level of congestion. CCID 4 is for use for senders that send small packets and would like a TCP- friendly sending rate, possibly with Explicit Congestion Notification (ECN), while minimizing abrupt rate changes. This memo defines an Experimental Protocol for the Internet community.

This document specifies TCP Friendly Rate Control (TFRC). TFRC is a congestion control mechanism for unicast flows operating in a best-effort Internet environment. It is reasonably fair when competing for bandwidth with TCP flows, but has a much lower variation of throughput over time compared with TCP, making it more suitable for applications such as streaming media where a relatively smooth sending rate is of importance.

This document obsoletes RFC 3448 and updates RFC 4342. [STANDARDS-TRACK]

This document specifies the use of Datagram Transport Layer Security (DTLS) over the Datagram Congestion Control Protocol (DCCP). DTLS provides communications privacy for applications that use datagram transport protocols and allows client/server applications to communicate in a way that is designed to prevent eavesdropping and detect tampering or message forgery. DCCP is a transport protocol that provides a congestion-controlled unreliable datagram service. [STANDARDS-TRACK]

This document proposes a mechanism for further experimentation, but not for widespread deployment at this time in the global Internet.

TCP-Friendly Rate Control (TFRC) is a congestion control mechanism for unicast flows operating in a best-effort Internet environment (RFC 3448). TFRC was intended for applications that use a fixed packet size, and was designed to be reasonably fair when competing for bandwidth with TCP connections using the same packet size. This document proposes TFRC-SP, a Small-Packet (SP) variant of TFRC, that is designed for applications that send small packets. The design goal for TFRC-SP is to achieve the same bandwidth in bps (bits per second) as a TCP flow using packets of up to 1500 bytes. TFRC-SP enforces a minimum interval of 10 ms between data packets to prevent a single flow from sending small packets arbitrarily frequently.

Flows using TFRC-SP compete reasonably fairly with large-packet TCP and TFRC flows in environments where large-packet flows and small-packet flows experience similar packet drop rates. However, in environments where small-packet flows experience lower packet drop rates than large-packet flows (e.g., with Drop-Tail queues in units of bytes), TFRC-SP can receive considerably more than its share of the bandwidth. This memo defines an Experimental Protocol for the Internet community.

This document contains the profile for Congestion Control Identifier 3, TCP-Friendly Rate Control (TFRC), in the Datagram Congestion Control Protocol (DCCP). CCID 3 should be used by senders that want a TCP-friendly sending rate, possibly with Explicit Congestion Notification (ECN), while minimizing abrupt rate changes. [STANDARDS-TRACK]

This document describes for the historical record the motivation behind the Datagram Congestion Control Protocol (DCCP), an unreliable transport protocol incorporating end-to-end congestion control. DCCP implements a congestion-controlled, unreliable flow of datagrams for use by applications such as streaming media or on-line games. This memo provides information for the Internet community.

The Datagram Congestion Control Protocol (DCCP) is a transport protocol that provides bidirectional unicast connections of congestion-controlled unreliable datagrams. DCCP is suitable for applications that transfer fairly large amounts of data and that can benefit from control over the tradeoff between timeliness and reliability. [STANDARDS-TRACK]

This document contains the profile for Congestion Control Identifier 2 (CCID 2), TCP-like Congestion Control, in the Datagram Congestion Control Protocol (DCCP). CCID 2 should be used by senders who would like to take advantage of the available bandwidth in an environment with rapidly changing conditions, and who are able to adapt to the abrupt changes in the congestion window typical of TCP's Additive Increase Multiplicative Decrease (AIMD) congestion control. [STANDARDS-TRACK]