Sender Queue Info Option for the SCTP Socket API
Simula Research Laboratory, Network Systems GroupMartin Linges vei 171364 FornebuAkershusNorway+47-6782-8200+47-6782-8201dreibh@simula.nohttp://www.iem.uni-due.de/~dreibh/Muenster University of Applied SciencesStegerwaldstraße 3948565 SteinfurtNordrhein-WestfalenGermanyseggelmann@fh-muenster.de
University of Duisburg-Essen,
Institute for Experimental MathematicsEllernstraße 2945326 EssenNordrhein-WestfalenGermany+49-201-183-7667+49-201-183-7673martin.becke@uni-due.deInternet-DraftThis document describes an extension to the SCTP sockets API for querying information about the sender queue.This draft describes an extension to the SCTP sockets API (see , ) which allows an application to query the sender queue utilization per stream. This information is necessary for applications to make efficient use of a mapping of streams to dissimilar paths. A detailed description including simulation results can be found in .In particular, this API extension is useful when using the CMT-SCTP, CMT/RPv1-SCTP, CMT/RPv2-SCTP and MPTCP-like extensions (see , , , , , , ) for Concurrent Multipath Transfer (CMT) with SCTP.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in
.This socket option obtains
the maximum sender queue size (in bytes),
the current total sender queue utilization (in bytes) as well as
the current utilization per stream (in bytes).The following structure is used to obtain the sender queue information:
This parameter is ignored for one-to-one style sockets. For one-to-many style sockets this parameter indicates which association the user is performing an action upon. It is an error to use SCTP_{CURRENT|ALL}_ASSOC in sq_assoc_id.
This field gives the maximum sender queue size in bytes.
This field gives the current total sender queue utilization in bytes.
This field gives the number of outgoing streams. That is, it will contain the number of valid sq_queued_on_stream entries.
This array gives the current number of bytes queued for the streams 0 to sq_number_of_streams-1.Note, that the caller of getsockopt() MUST provide a sctp_sndqueueinfo structure which can hold at least as many sq_queued_on_stream entries as the association's number of outgoing streams. Otherwise, the getsockopt() call will fail and return an error.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 for the SCTP sockets API are described by
.This document does not require IANA actions.
The authors would like to thank
Michael Tuexen and Irene Ruengeler
for their support.