]> Simula Metropolitan Centre for Digital Engineering

Stensberggata 27 0170 Oslo Norway dreibh@simula.no https://www.simula.no/people/dreibh

HAW Hamburg, Informatics Department

Berliner Tor 7 20099 Hamburg Germany +49-40-42875-8104 martin.becke@haw-hamburg.de http://www.scimbe.de/about.html

University of Duisburg-Essen, Institute for Experimental Mathematics

Ellernstraße 29 45326 Essen Germany hakim.adhari@uni-due.de

Internet-Draft This document describes extensions to the SCTP sockets API for configuring the CMT-SCTP and CMT/RP-SCTP extensions.

Introduction This draft describes extensions to the SCTP sockets API (see , ) which allow an application to configure the behaviour of the Concurrent Multipath Transfer (CMT) extensions CMT-SCTP, CMT/RPv1-SCTP, CMT/RPv2-SCTP and MPTCP-like (see , , , , , , , , ).

Concurrent Multipath Transfer and Resource Pooling Activation/Deactivation (SCTP_CMT_ON_OFF) This socket option activates or deactivates CMT and sets the corresponding Resource Pooling variant to be applied. The sctp_assoc_value structure is used to specify the association for which the CMT state should be changed and the new CMT state. Definition of the sctp_assoc_value structure:

assoc_id:

Holds the identifier for the association of which the CMT state should be changed. Ignored for one-to-one style sockets.

assoc_value:

0

Turns CMT off.

1

Turns plain CMT-SCTP on. No Resource Pooling is applied.

2

Turns CMT-SCTP on. CMT/RPv1 Resource Pooling as defined in is applied.

3

Turns CMT-SCTP on. CMT/RPv2 Resource Pooling as defined in is applied.

4

Turns CMT-SCTP on. MPTCP-like Resource Pooling as defined in , , is applied.

Testbed Platform A large-scale and realistic Internet testbed platform with support for the multi-homing feature of the underlying SCTP protocol is NorNet. A description of NorNet is provided in , , some further information can be found on the project website .

Security Considerations Security considerations for the SCTP sockets API are described by .

IANA Considerations This document does not require IANA actions.

Acknowledgments The authors would like to thank Michael Tuexen for his support.

References Normative References This document obsoletes RFC 2960 and RFC 3309. It describes the Stream Control Transmission Protocol (SCTP). SCTP is designed to transport Public Switched Telephone Network (PSTN) signaling messages over IP networks, but is capable of broader applications. 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: -- acknowledged error-free non-duplicated transfer of user data, -- data fragmentation to conform to discovered path MTU size, -- sequenced delivery of user messages within multiple streams, with an option for order-of-arrival delivery of individual user messages, -- optional bundling of multiple user messages into a single SCTP packet, and -- network-level fault tolerance through supporting of multi-homing at either or both ends of an association. The design of SCTP includes appropriate congestion avoidance behavior and resistance to flooding and masquerade attacks. [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. University of Delaware HAW Hamburg SimulaMet University of Delaware Franklin and Marshall College Cisco Systems Netflix Muenster Univ. of Appl. Sciences The Stream Control Transmission Protocol (SCTP) supports multi-homing for providing network fault tolerance. However, mainly one path is used for data transmission. Only timer-based retransmissions are carried over other paths as well. This document describes how multiple paths can be used simultaneously for transmitting user messages. Informative References