draft-ietf-taps-transports-usage-04.txt   draft-ietf-taps-transports-usage-05.txt 
TAPS M. Welzl TAPS M. Welzl
Internet-Draft University of Oslo Internet-Draft University of Oslo
Intended status: Informational M. Tuexen Intended status: Informational M. Tuexen
Expires: October 7, 2017 Muenster Univ. of Appl. Sciences Expires: November 25, 2017 Muenster Univ. of Appl. Sciences
N. Khademi N. Khademi
University of Oslo University of Oslo
April 5, 2017 May 24, 2017
On the Usage of Transport Features Provided by IETF Transport Protocols On the Usage of Transport Features Provided by IETF Transport Protocols
draft-ietf-taps-transports-usage-04 draft-ietf-taps-transports-usage-05
Abstract Abstract
This document describes how TCP, MPTCP, SCTP, UDP and UDP-Lite expose This document describes how the transport protocols Transmission
services to applications and how an application can configure and use Control Protocol (TCP), MultiPath TCP (MPTCP), Stream Control
the transport features that make up these services. It also Transmission Protocol (SCTP), User Datagram Protocol (UDP) and
discusses the service provided by the LEDBAT congestion control Lightweight User Datagram Protocol (UDP-Lite) expose services to
mechanism. applications and how an application can configure and use the
features that make up these services. It also discusses the service
provided by the Low Extra Delay Background Transport (LEDBAT)
congestion control mechanism.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 7, 2017. This Internet-Draft will expire on November 25, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Pass 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Pass 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Primitives Provided by TCP . . . . . . . . . . . . . . . . 5 3.1. Primitives Provided by TCP . . . . . . . . . . . . . . . 5
3.1.1. Excluded Primitives or Parameters . . . . . . . . . . 8 3.1.1. Excluded Primitives or Parameters . . . . . . . . . . 9
3.2. Primitives Provided by MPTCP . . . . . . . . . . . . . . . 9 3.2. Primitives Provided by MPTCP . . . . . . . . . . . . . . 9
3.3. Primitives Provided by SCTP . . . . . . . . . . . . . . . 10 3.3. Primitives Provided by SCTP . . . . . . . . . . . . . . . 10
3.3.1. Excluded Primitives or Parameters . . . . . . . . . . 17 3.3.1. Excluded Primitives or Parameters . . . . . . . . . . 18
3.4. Primitives Provided by UDP and UDP-Lite . . . . . . . . . 18 3.4. Primitives Provided by UDP and UDP-Lite . . . . . . . . . 18
3.5. The service of LEDBAT . . . . . . . . . . . . . . . . . . 18 3.5. The service of LEDBAT . . . . . . . . . . . . . . . . . . 19
4. Pass 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4. Pass 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1. CONNECTION Related Primitives . . . . . . . . . . . . . . 20 4.1. CONNECTION Related Primitives . . . . . . . . . . . . . . 21
4.2. DATA Transfer Related Primitives . . . . . . . . . . . . . 31 4.2. DATA Transfer Related Primitives . . . . . . . . . . . . 36
5. Pass 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5. Pass 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.1. CONNECTION Related Transport Features . . . . . . . . . . 34 5.1. CONNECTION Related Transport Features . . . . . . . . . . 39
5.2. DATA Transfer Related Transport Features . . . . . . . . . 40 5.2. DATA Transfer Related Transport Features . . . . . . . . 47
5.2.1. Sending Data . . . . . . . . . . . . . . . . . . . . . 40 5.2.1. Sending Data . . . . . . . . . . . . . . . . . . . . 48
5.2.2. Receiving Data . . . . . . . . . . . . . . . . . . . . 41 5.2.2. Receiving Data . . . . . . . . . . . . . . . . . . . 49
5.2.3. Errors . . . . . . . . . . . . . . . . . . . . . . . . 41 5.2.3. Errors . . . . . . . . . . . . . . . . . . . . . . . 50
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 42 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 50
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 51
8. Security Considerations . . . . . . . . . . . . . . . . . . . 42 8. Security Considerations . . . . . . . . . . . . . . . . . . . 51
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 51
9.1. Normative References . . . . . . . . . . . . . . . . . . . 42 9.1. Normative References . . . . . . . . . . . . . . . . . . 51
9.2. Informative References . . . . . . . . . . . . . . . . . . 45 9.2. Informative References . . . . . . . . . . . . . . . . . 54
Appendix A. Overview of RFCs used as input for pass 1 . . . . . . 46 Appendix A. Overview of RFCs used as input for pass 1 . . . . . 55
Appendix B. How this document was developed . . . . . . . . . . . 46 Appendix B. How this document was developed . . . . . . . . . . 55
Appendix C. Revision information . . . . . . . . . . . . . . . . 48 Appendix C. Revision information . . . . . . . . . . . . . . . . 57
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 49 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 58
1. Terminology 1. Terminology
Transport Feature: a specific end-to-end feature that the transport Transport Feature: a specific end-to-end feature that the transport
layer provides to an application. Examples include layer provides to an application. Examples include
confidentiality, reliable delivery, ordered delivery, message- confidentiality, reliable delivery, ordered delivery, message-
versus-stream orientation, etc. versus-stream orientation, etc.
Transport Service: a set of Transport Features, without an Transport Service: a set of Transport Features, without an
association to any given framing protocol, which provides a association to any given framing protocol, which provides a
complete service to an application. complete service to an application.
skipping to change at page 3, line 31 skipping to change at page 3, line 22
implements a single transport service, e.g., a protocol stack (RTP implements a single transport service, e.g., a protocol stack (RTP
over UDP). over UDP).
Application: an entity that uses the transport layer for end-to-end Application: an entity that uses the transport layer for end-to-end
delivery of data across the network (this may also be an upper delivery of data across the network (this may also be an upper
layer protocol or tunnel encapsulation). layer protocol or tunnel encapsulation).
Endpoint: an entity that communicates with one or more other Endpoint: an entity that communicates with one or more other
endpoints using a transport protocol. endpoints using a transport protocol.
Connection: shared state of two or more endpoints that persists Connection: shared state of two or more endpoints that persists
across messages that are transmitted between these endpoints. across messages that are transmitted between these endpoints.
Primitive: a function call that is used to locally communicate Primitive: a function call that is used to locally communicate
between an application and a transport endpoint and is related to between an application and a transport endpoint. A primitive is
one or more Transport Features. related to one or more Transport Features.
Event: a primitive that is invoked by a transport endpoint.
Parameter: a value passed between an application and a transport Parameter: a value passed between an application and a transport
protocol by a primitive. protocol by a primitive.
Socket: the combination of a destination IP address and a Socket: the combination of a destination IP address and a
destination port number. destination port number.
Transport Address: the combination of an IP address, transport Transport Address: the combination of an IP address, transport
protocol and the port number used by the transport protocol. protocol and the port number used by the transport protocol.
2. Introduction 2. Introduction
This document presents defined interactions between applications and This document presents, in the form of primitives, events and
the transport protocols TCP, MPTCP, SCTP, UDP and UDP-Lite as well as transport features, defined interactions between applications and the
the LEDBAT congestion control mechanism in the form of primitives and following unicast transport protocols: Transmission Control Protocol
Transport Features. Primitives can be invoked by an application or a (TCP), MultiPath TCP (MPTCP), Stream Control Transmission Protocol
transport protocol; the latter type is called an "event". The list (SCTP), User Datagram Protocol (UDP), Lightweight User Datagram
of primitives and Transport Features in this document is strictly Protocol (UDP-Lite). It also defines a primitive to enable/disable
based on the parts of protocol specifications that describe what the and configure the Low Extra Delay Background Transport (LEDBAT)
protocol provides to an application using it and how the application unicast congestion control mechanism. Transport protocols provide
interacts with it. Together with [RFC8095], it provides the basis communication between processes that operate on network endpoints,
for the minimal set of transport services that end systems should which means that they allow for multiplexing of communication between
support; this minimal set is derived in the same IP addresses, and normally this multiplexing is achieved
using port numbers. Port multiplexing is therefore assumed to be
always provided and not discussed in this document.
The list of primitives, events and transport features in this
document is strictly based on the parts of protocol specifications
that describe what the protocol provides to an application using it
and how the application interacts with it. Together with an overview
of the services provided by IETF transport protocols and congestion
control mechanisms [RFC8095] and an analysis of UDP and UDP-Lite
[FJ16], it provides the basis for the minimal set of transport
services that end systems should support
[I-D.draft-gjessing-taps-minset]. [I-D.draft-gjessing-taps-minset].
Parts of a protocol that are explicitly stated as optional to Parts of a protocol that are explicitly stated as optional to
implement are not covered. Interactions between the application and implement are not covered. Interactions between the application and
a transport protocol that are not directly related to the operation a transport protocol that are not directly related to the operation
of the protocol are also not covered. For example, [RFC6458] of the protocol are also not covered. For example, there are various
explains how an application can use socket options to indicate its ways for an application to use socket options to indicate its
interest in receiving certain notifications. However, for the interest in receiving certain notifications [RFC6458]. However, for
purpose of identifying primitives and Transport Services, the ability the purpose of identifying primitives, events and transport features,
to enable or disable the reception of notifications is irrelevant. the ability to enable or disable the reception of notifications is
Similarly, one-to-many style sockets described in [RFC6458] just irrelevant. Similarly, "one-to-many style sockets" [RFC6458] just
affect the application programming style, not how the underlying affect the application programming style, not how the underlying
protocol operates, and they are therefore not discussed here. The protocol operates, and they are therefore not discussed here. The
same is true for the ability to obtain the unchanged value of a same is true for the ability to obtain the unchanged value of a
parameter that an application has previously set (this is the case parameter that an application has previously set (e.g.,via "get" in
for the "get" in many get/set operations in [RFC6458]). get/set operations [RFC6458]).
The document presents a three-pass process to arrive at a list of The document presents a three-pass process to arrive at a list of
Transport Features. In the first pass, the relevant RFC text is transport features. In the first pass, the relevant RFC text is
discussed per protocol. In the second pass, this discussion is used discussed per protocol. In the second pass, this discussion is used
to derive a list of primitives that are uniformly categorized across to derive a list of primitives and events that are uniformly
protocols. Here, an attempt is made to present or -- where text categorized across protocols. Here, an attempt is made to present or
describing primitives does not yet exist -- construct primitives in a -- where text describing primitives or events does not yet exist --
slightly generalized form to highlight similarities. This is, for construct primitives or events in a slightly generalized form to
example, achieved by renaming primitives of protocols or by avoiding highlight similarities. This is, for example, achieved by renaming
a strict 1:1-mapping between the primitives in the protocol primitives or events of protocols or by avoiding a strict 1:1-mapping
specification and primitives in the list. Finally, the third pass between the primitives or events in the protocol specification and
presents Transport Features based on pass 2, identifying which primitives or events in the list. Finally, the third pass presents
protocols implement them. transport features based on pass 2, identifying which protocols
implement them.
In the list resulting from the second pass, some Transport Features In the list resulting from the second pass, some transport features
are missing because they are implicit in some protocols, and they are missing because they are implicit in some protocols, and they
only become explicit when we consider the superset of all features only become explicit when we consider the superset of all transport
offered by all protocols. For example, TCP always carries out features offered by all protocols. For example, TCP always carries
congestion control; we have to consider it together with a protocol out congestion control; we have to consider it together with a
like UDP (which does not have congestion control) before we can protocol like UDP (which does not have congestion control) before we
consider congestion control as a Transport Feature. The complete can consider congestion control as a transport feature. The complete
list of features across all protocols is therefore only available list of transport features across all protocols is therefore only
after pass 3. available after pass 3.
This document discusses unicast transport protocols and a unicast
congestion control mechanism. Transport protocols provide
communication between processes that operate on network endpoints,
which means that they allow for multiplexing of communication between
the same IP addresses, and normally this multiplexing is achieved
using port numbers. Port multiplexing is therefore assumed to be
always provided and not discussed in this document.
Some protocols are connection-oriented. Connection-oriented Some protocols are connection-oriented. Connection-oriented
protocols often use an initial call to a specific transport primitive protocols often use an initial call to a specific primitive to open a
to open a connection before communication can progress, and require connection before communication can progress, and require
communication to be explicitly terminated by issuing another call to communication to be explicitly terminated by issuing another call to
a transport primitive (usually called "close"). A "connection" is a primitive (usually called "close"). A "connection" is the common
the common state that some transport primitives refer to, e.g., to state that some transport primitives refer to, e.g., to adjust
adjust general configuration settings. Connection establishment, general configuration settings. Connection establishment,
maintenance and termination are therefore used to categorize maintenance and termination are therefore used to categorize
transport primitives of connection-oriented transport protocols in transport primitives of connection-oriented transport protocols in
pass 2 and pass 3. For this purpose, UDP is assumed to be used with pass 2 and pass 3. For this purpose, UDP is assumed to be used with
"connected" sockets, i.e. sockets that are bound to a specific pair "connected" sockets, i.e. sockets that are bound to a specific pair
of addresses and ports [FJ16]. of addresses and ports [FJ16].
3. Pass 1 3. Pass 1
This first iteration summarizes the relevant text parts of the RFCs This first iteration summarizes the relevant text parts of the RFCs
describing the protocols, focusing on what each transport protocol describing the protocols, focusing on what each transport protocol
provides to the application and how it is used (abstract API provides to the application and how it is used (abstract API
descriptions, where they are available). descriptions, where they are available).
3.1. Primitives Provided by TCP 3.1. Primitives Provided by TCP
[RFC0793] states: "The Transmission Control Protocol (TCP) is The initial TCP specification [RFC0793] states: "The Transmission
intended for use as a highly reliable host-to-host protocol between Control Protocol (TCP) is intended for use as a highly reliable host-
hosts in packet-switched computer communication networks, and in to-host protocol between hosts in packet-switched computer
interconnected systems of such networks". Section 3.8 in [RFC0793] communication networks, and in interconnected systems of such
further specifies the interaction with the application by listing networks". Section 3.8 in this specification [RFC0793] further
several transport primitives. It is also assumed that an Operating specifies the interaction with the application by listing several
System provides a means for TCP to asynchronously signal the transport primitives. It is also assumed that an Operating System
application; the primitives representing such signals are called provides a means for TCP to asynchronously signal the application;
'events' in this section. This section describes the relevant the primitives representing such signals are called 'events' in this
primitives. section. This section describes the relevant primitives.
open: this is either active or passive, to initiate a connection or open: this is either active or passive, to initiate a connection or
listen for incoming connections. All other primitives are listen for incoming connections. All other primitives are
associated with a specific connection, which is assumed to first associated with a specific connection, which is assumed to first
have been opened. An active open call contains a socket. A have been opened. An active open call contains a socket. A
passive open call with a socket waits for a particular connection; passive open call with a socket waits for a particular connection;
alternatively, a passive open call can leave the socket alternatively, a passive open call can leave the socket
unspecified to accept any incoming connection. A fully specified unspecified to accept any incoming connection. A fully specified
passive call can later be made active by calling 'send'. passive call can later be made active by calling 'send'.
Optionally, a timeout can be specified, after which TCP will abort Optionally, a timeout can be specified, after which TCP will abort
the connection if data has not been successfully delivered to the the connection if data has not been successfully delivered to the
destination (else a default timeout value is used). [RFC1122] destination (else a default timeout value is used). A procedure
describes a procedure for aborting the connection that must be for aborting the connection is used to avoid excessive
used to avoid excessive retransmissions, and states that an retransmissions, and an application is able to control the
application must be able to control the threshold used to threshold used to determine the condition for aborting; this
determine the condition for aborting -- and that this threshold threshold may be measured in time units or as a count of
may be measured in time units or as a count of retransmission. retransmission [RFC1122]. This indicates that the timeout could
This indicates that the timeout could also be specified as a count also be specified as a count of retransmission.
of retransmission.
Also optional, for multihomed hosts, the local IP address can be Also optional, for multihomed hosts, the local IP address can be
provided [RFC1122]. If it is not provided, a default choice will provided [RFC1122]. If it is not provided, a default choice will
be made in case of active open calls. A passive open call will be made in case of active open calls. A passive open call will
await incoming connection requests to all local addresses and then await incoming connection requests to all local addresses and then
maintain usage of the local IP address where the incoming maintain usage of the local IP address where the incoming
connection request has arrived. Finally, the 'options' parameter connection request has arrived. Finally, the 'options' parameter
is explained in [RFC1122] to allow the application to specify IP allows the application to specify IP options such as source route,
options such as source route, record route, or timestamp. It is record route, or timestamp [RFC1122]. It is not stated on which
not stated on which segments of a connection these options should segments of a connection these options should be applied, but
be applied, but probably all segments, as this is also stated in a probably all segments, as this is also stated in a specification
specification given for the usage of source route (section 4.2.3.8 given for the usage of source route (section 4.2.3.8 of
of [RFC1122]). Source route is the only non-optional IP option in [RFC1122]). Source route is the only non-optional IP option in
this parameter, allowing an application to specify a source route this parameter, allowing an application to specify a source route
when it actively opens a TCP connection. when it actively opens a TCP connection.
Master Key Tuples (MKTs) for authentication can optionally be Master Key Tuples (MKTs) for authentication can optionally be
configured when calling open (section 7.1 of [RFC5925]). configured when calling open (section 7.1 of [RFC5925]). When
authentication is in use, complete TCP segments are authenticated,
including the TCP IPv4 pseudoheader, TCP header, and TCP data.
TCP Fast Open (TFO) [RFC7413] allows to immediately hand over a TCP Fast Open (TFO) [RFC7413] allows to immediately hand over a
message from the active open to the passive open side of a TCP message from the active open to the passive open side of a TCP
connection together with the first message establishment packet connection together with the first message establishment packet
(the SYN). This can be useful for applications that are sensitive (the SYN). This can be useful for applications that are sensitive
to TCP's connection setup delay. TCP implementations MUST NOT use to TCP's connection setup delay. TCP implementations MUST NOT use
TFO by default, but only use TFO if requested explicitly by the TFO by default, but only use TFO if requested explicitly by the
application on a per-service-port basis. To benefit from TFO, the application on a per-service-port basis. more than TCP's maximum
first application data unit (e.g., an HTTP request) needs to be no segment size (minus options used in the SYN). For the active open
more than TCP's maximum segment size (minus options used in the side, it is recommended to change or replace the connect() call in
SYN). For the active open side, [RFC7413] recommends changing or order to support a user data buffer argument [RFC7413]. For the
replacing the connect() call in order to support a user data passive open side, the application needs to enable the reception
buffer argument. For the passive open side, the application needs of Fast Open requests, e.g. via a new TCP_FASTOPEN setsockopt()
to enable the reception of Fast Open requests, e.g. via a new socket option before listen(). The receiving application must be
TCP_FASTOPEN setsockopt() socket option before listen(). The prepared to accept duplicates of the TFO message, as the first
receiving application must be prepared to accept duplicates of the data written to a socket can be delivered more than once to the
TFO message, as the first data written to a socket can be application on the remote host.
delivered more than once to the application on the remote host.
send: this is the primitive that an application uses to give the send: this is the primitive that an application uses to give the
local TCP transport endpoint a number of bytes that TCP should local TCP transport endpoint a number of bytes that TCP should
reliably send to the other side of the connection. The URGENT reliably send to the other side of the connection. The URGENT
flag, if set, states that the data handed over by this send call flag, if set, states that the data handed over by this send call
is urgent and this urgency should be indicated to the receiving is urgent and this urgency should be indicated to the receiving
process in case the receiving application has not yet consumed all process in case the receiving application has not yet consumed all
non-urgent data preceding it. An optional timeout parameter can non-urgent data preceding it. An optional timeout parameter can
be provided that updates the connection's timeout (see 'open'). be provided that updates the connection's timeout (see 'open').
Additionally, optional parameters allow to indicate the preferred Additionally, optional parameters allow to indicate the preferred
skipping to change at page 7, line 40 skipping to change at page 7, line 38
close event: TCP uses this primitive to inform an application that close event: TCP uses this primitive to inform an application that
the application on the other side has called the 'close' the application on the other side has called the 'close'
primitive, so the local application can also issue a 'close' and primitive, so the local application can also issue a 'close' and
terminate the connection gracefully. See [RFC0793], Section 3.5. terminate the connection gracefully. See [RFC0793], Section 3.5.
abort event: When TCP aborts a connection upon receiving a "Reset" abort event: When TCP aborts a connection upon receiving a "Reset"
from the peer, it "advises the user and goes to the CLOSED state." from the peer, it "advises the user and goes to the CLOSED state."
See [RFC0793], Section 3.4. See [RFC0793], Section 3.4.
USER TIMEOUT event: This event, described in Section 3.9 of USER TIMEOUT event: This event is executed when the user timeout
[RFC0793], is executed when the user timeout expires (see 'open'). expires (see 'open') (section 3.9 of [RFC0793]). All queues are
All queues are flushed and the application is informed that the flushed and the application is informed that the connection had to
connection had to be aborted due to user timeout. be aborted due to user timeout.
ERROR_REPORT event: This event, described in Section 4.2.4.1 of ERROR_REPORT event: This event informs the application of "soft
[RFC1122], informs the application of "soft errors" that can be errors" that can be safely ignored [RFC5461], including the
safely ignored [RFC5461], including the arrival of an ICMP error arrival of an ICMP error message or excessive retransmissions
message or excessive retransmissions (reaching a threshold below (reaching a threshold below the threshold where the connection is
the threshold where the connection is aborted). aborted). See section 4.2.4.1 of [RFC1122].
Type-of-Service: Section 4.2.4.2 of [RFC1122] states that the Type-of-Service: Section 4.2.4.2 of the requirements for Internet
application layer MUST be able to specify the Type-of-Service hosts [RFC1122] states that the application layer MUST be able to
(TOS) for segments that are sent on a connection. The application specify the Type-of-Service (TOS) for segments that are sent on a
should be able to change the TOS during the connection lifetime, connection. The application should be able to change the TOS
and the TOS value should be passed to the IP layer unchanged. during the connection lifetime, and the TOS value should be passed
Since then the TOS field has been redefined. A part of the field to the IP layer unchanged. Since then the TOS field has been
has been assigned to ECN [RFC3168] and the six most significant redefined. The Differentiated Services (diffuser) model [RFC2475]
bits have been assigned to carry the DiffServ CodePoint, DSField [RFC3260] replaces this field in the IP Header, assigning the six
[RFC3260]. Staying with the intention behind the application's most significant bits to carry the Differentiated Services Code
ability to specify the "Type of Service", this should probably be Point (DSCP) field [RFC2474].
interpreted to mean the value in the DSField, which is the
Differentiated Services Codepoint (DSCP).
Nagle: The Nagle algorithm, described in Section 4.2.3.4 of Nagle: The Nagle algorithm delays sending data for some time to
[RFC1122], delays sending data for some time to increase the increase the likelihood of sending a full-sized segment (section
likelihood of sending a full-sized segment. An application can 4.2.3.4 of [RFC1122]). An application can disable the Nagle
disable the Nagle algorithm for an individual connection. algorithm for an individual connection.
User Timeout Option: The User Timeout Option (UTO) [RFC5482] allows User Timeout Option: The User Timeout Option (UTO) [RFC5482] allows
one end of a TCP connection to advertise its current user timeout one end of a TCP connection to advertise its current user timeout
value so that the other end of the TCP connection can adapt its value so that the other end of the TCP connection can adapt its
own user timeout accordingly. In addition to the configurable own user timeout accordingly. In addition to the configurable
value of the User Timeout (see 'send'), [RFC5482] introduces three value of the User Timeout (see 'send'), there are three per-
per-connection state variables that an application can adjust to connection state variables that an application can adjust to
control the operation of the User Timeout Option (UTO): ADV_UTO is control the operation of the User Timeout Option (UTO): ADV_UTO is
the value of the UTO advertised to the remote TCP peer (default: the value of the UTO advertised to the remote TCP peer (default:
system-wide default user timeout); ENABLED (default false) is a system-wide default user timeout); ENABLED (default false) is a
boolean-type flag that controls whether the UTO option is enabled boolean-type flag that controls whether the UTO option is enabled
for a connection. This applies to both sending and receiving. for a connection. This applies to both sending and receiving.
CHANGEABLE is a boolean-type flag (default true) that controls CHANGEABLE is a boolean-type flag (default true) that controls
whether the user timeout may be changed based on a UTO option whether the user timeout may be changed based on a UTO option
received from the other end of the connection. CHANGEABLE becomes received from the other end of the connection. CHANGEABLE becomes
false when an application explicitly sets the user timeout (see false when an application explicitly sets the user timeout (see
'send'). 'send').
3.1.1. Excluded Primitives or Parameters Set / Get Authentication Parameters: The preferred outgoing MKT
(current_key) and/or the preferred incoming MKT (rnext_key) of a
connection can be configured. Information about current_key and
rnext_key carried in a recently received segment can be retrieved
(section 7.1 of [RFC5925]).
The 'open' primitive specified in [RFC0793] can be handed optional 3.1.1. Excluded Primitives or Parameters
Precedence or security/compartment information according to
[RFC0793], but this was not included here because it is mostly
irrelevant today, as explained in [RFC7414].
The 'status' primitive was not included because [RFC0793] describes The 'open' primitive can be handed optional Precedence or security/
this primitive as "implementation dependent" and states that it compartment information [RFC0793], but this was not included here
"could be excluded without adverse effect". Moreover, while a data because it is mostly irrelevant today [RFC7414].
block containing specific information is described, it is also stated
that not all of this information may always be available. While
[RFC5925] states that 'status' SHOULD be augmented to allow the MKTs The 'status' primitive was not included because the initial TCP
of a current or pending connection to be read (for confirmation), the specification describes this primitive as "implementation dependent"
same information is also available via 'receive', which MUST be and states that it "could be excluded without adverse effect"
augmented with that functionality according to [RFC5925]. The 'send' [RFC0793]. Moreover, while a data block containing specific
primitive described in [RFC0793] includes an optional PUSH flag information is described, it is also stated that not all of this
which, if set, requires data to be promptly transmitted to the information may always be available. While 'status' SHOULD be
receiver without delay; the 'receive' primitive described in augmented to allow the MKTs of a current or pending connection to be
[RFC0793] can (under some conditions) yield the status of the PUSH read (for confirmation), the same information is also available via
flag. Because PUSH functionality is made optional to implement for 'receive', which MUST be augmented with that functionality [RFC5925].
both the 'send' and 'receive' primitives in [RFC1122], this The 'send' primitive includes an optional PUSH flag which, if set,
functionality is not included here. [RFC1122] also introduces keep- requires data to be promptly transmitted to the receiver without
alives to TCP, but these are optional to implement and hence not delay [RFC0793]; the 'receive' primitive described in can (under some
considered here. [RFC1122] describes that "some TCP implementations conditions) yield the status of the PUSH flag. Because PUSH
have included a FLUSH call", indicating that this call is also functionality is optional to implement for both the 'send' and
optional to implement. It is therefore not considered here. 'receive' primitives [RFC1122], this functionality is not included
here. The requirements for Internet hosts [RFC1122] also introduce
keep-alives to TCP, but these are optional to implement and hence not
considered here. The same document also describes that "some TCP
implementations have included a FLUSH call", indicating that this
call is also optional to implement. It is therefore not considered
here.
3.2. Primitives Provided by MPTCP 3.2. Primitives Provided by MPTCP
Multipath TCP (MPTCP) is an extension to TCP that allows the use of Multipath TCP (MPTCP) is an extension to TCP that allows the use of
multiple paths for a single data-stream. It achieves this by multiple paths for a single data-stream. It achieves this by
creating different so-called TCP subflows for each of the interfaces creating different so-called TCP subflows for each of the interfaces
and scheduling the traffic across these TCP subflows. The service and scheduling the traffic across these TCP subflows. The service
provided by MPTCP is described in [RFC6182] "Multipath TCP MUST provided by MPTCP is described as follows [RFC6182]: "Multipath TCP
follow the same service model as TCP [RFC0793]: in- order, reliable, MUST follow the same service model as TCP [RFC0793]: in- order,
and byte-oriented delivery. Furthermore, a Multipath TCP connection reliable, and byte-oriented delivery. Furthermore, a Multipath TCP
SHOULD provide the application with no worse throughput or resilience connection SHOULD provide the application with no worse throughput or
than it would expect from running a single TCP connection over any resilience than it would expect from running a single TCP connection
one of its available paths." over any one of its available paths."
Further, [RFC6182] states constraints on the API exposed by MPTCP: "A Further, there are some constraints on the API exposed by MPTCP
multipath-capable equivalent of TCP MUST retain some level of [RFC6182]: "A multipath-capable equivalent of TCP MUST retain some
backward compatibility with existing TCP APIs, so that existing level of backward compatibility with existing TCP APIs, so that
applications can use the newer merely by upgrading the operating existing applications can use the newer merely by upgrading the
systems of the end hosts." As such, the primitives provided by MPTCP operating systems of the end hosts." As such, the primitives
are equivalent to the ones provided by TCP. Nevertheless, [RFC6824] provided by MPTCP are equivalent to the ones provided by TCP.
and [RFC6897] clarify some parts of TCP's primitives with respect to Nevertheless, the MPTCP RFCs [RFC6824] and [RFC6897] clarify some
MPTCP and add some extensions for better control on MPTCP's subflows. parts of TCP's primitives with respect to MPTCP and add some
Hereafter is a list of the clarifications and extensions the above extensions for better control on MPTCP's subflows. Hereafter is a
cited RFCs provide to TCP's primitives. list of the clarifications and extensions the above cited RFCs
provide to TCP's primitives.
open: [RFC6897] states "An application should be able to request to open: "An application should be able to request to turn on or turn
turn on or turn off the usage of MPTCP.". The RFC states that off the usage of MPTCP" [RFC6897]. This functionality can be
this functionality can be provided through a socket-option called provided through a socket-option called TCP_MULTIPATH_ENABLE.
TCP_MULTIPATH_ENABLE. Further, [RFC6897] says that MPTCP must be Further, MPTCP must be disabled in case the application is binding
disabled in case the application is binding to a specific address. to a specific address [RFC6897].
send/receive: [RFC6824] states that the sending and receiving of send/receive: The sending and receiving of data does not require any
data does not require any changes to the application when MPTCP is changes to the application when MPTCP is being used [RFC6824].
being used. The MPTCP-layer will "take one input data stream from The MPTCP-layer will "take one input data stream from an
an application, and split it into one or more subflows, with application, and split it into one or more subflows, with
sufficient control information to allow it to be reassembled and sufficient control information to allow it to be reassembled and
delivered reliably and in order to the recipient application." delivered reliably and in order to the recipient application."
The use of the Urgent-Pointer is special in MPTCP and [RFC6824] The use of the Urgent-Pointer is special in MPTCP [RFC6824]: "a
says "a TCP subflow MUST NOT use the Urgent Pointer to interrupt TCP subflow MUST NOT use the Urgent Pointer to interrupt an
an existing mapping." existing mapping."
address and subflow management: MPTCP uses different addresses and address and subflow management: MPTCP uses different addresses and
allows a host to announce these addresses as part of the protocol. allows a host to announce these addresses as part of the protocol.
[RFC6897] says "An application should be able to restrict MPTCP to The MPTCP API Considerations RFC [RFC6897] says "An application
binding to a given set of addresses." and thus allows applications should be able to restrict MPTCP to binding to a given set of
to limit the set of addresses that are being used by MPTCP. addresses" and thus allows applications to limit the set of
Further, "An application should be able to obtain information on addresses that are being used by MPTCP. Further, "An application
the pairs of addresses used by the MPTCP subflows.". should be able to obtain information on the pairs of addresses
used by the MPTCP subflows".
3.3. Primitives Provided by SCTP 3.3. Primitives Provided by SCTP
Section 1.1 of [RFC4960] lists limitations of TCP that SCTP removes. TCP has a number of limitations that SCPT removes (section 1.1 of
Three of the four mentioned limitations directly translate into [RFC4960]). The following three removed limitations directly
Transport Features that are visible to an application using SCTP: 1) translate into transport features that are visible to an application
it allows for preservation of message delineations; 2) these using SCTP: 1) it allows for preservation of message delineations; 2)
messages, while reliably transferred, do not require to be in order these messages, while reliably transferred, do not require to be in
unless the application wants it; 3) multi-homing is supported. In order unless the application wants it; 3) multi-homing is supported.
SCTP, connections are called "associations" and they can be between In SCTP, connections are called "associations" and they can be
not only two (as in TCP) but multiple addresses at each endpoint. between not only two (as in TCP) but multiple addresses at each
endpoint.
Section 10 of [RFC4960] further specifies the interaction with the Section 10 of the SCTP base protocol specification [RFC4960]
application (which RFC [RFC4960] calls the "Upper Layer Protocol" specifies the interaction with the application (which this RFC calls
(ULP)). It is assumed that the Operating System provides a means for the "Upper Layer Protocol" (ULP)). It is assumed that the Operating
SCTP to asynchronously signal the application; the primitives System provides a means for SCTP to asynchronously signal the
representing such signals are called 'events' in this section. Here, application; the primitives representing such signals are called
we describe the relevant primitives. In addition to the abstract API 'events' in this section. Here, we describe the relevant primitives.
described in Section 10 of [RFC4960], an extension to the socket API In addition to the abstract API described in the section 10 of the
is described in [RFC6458], covering the functionality of the base SCTP base protocol specification [RFC4960], an extension to the
protocol specified in [RFC4960] and its extensions specified in socket API is described in [RFC6458]. This covers the functionality
[RFC3758], [RFC4895], and [RFC5061]. For the protocol extensions of the base protocol [RFC4960] and some of its extensions [RFC3758],
specified in [RFC6525], [RFC6951], [RFC7053], [RFC7496], [RFC7829] [RFC4895], [RFC5061]. For other protocol extensions [RFC6525],
and [I-D.ietf-tsvwg-sctp-ndata], the corresponding extensions of the [RFC6951], [RFC7053], [RFC7496], [RFC7829],
[I-D.ietf-tsvwg-sctp-ndata], the corresponding extensions of the
socket API are specified in these protocol specifications. The socket API are specified in these protocol specifications. The
functionality exposed to the ULP through this socket API is functionality exposed to the ULP through the all these APIs is
considered here in addition to the abstract API specified in Section considered here.
10 of [RFC4960].
[RFC4960] contains a "SETPROTOCOLPARAMETERS" primitive that allows to The abstract API contains a "SETPROTOCOLPARAMETERS" primitive that
adjust elements of a parameter list; it is stated that SCTP allows to adjust elements of a parameter list [RFC4960]; it is stated
implementations "may allow ULP to customize some of these protocol that SCTP implementations "may allow ULP to customize some of these
parameters", indicating that none of the elements of this parameter protocol parameters", indicating that none of the elements of this
list are mandatory to make ULP-configurable. Thus, we only consider parameter list are mandatory to make ULP-configurable. Thus, we only
the parameters in [RFC4960] that are also covered in one of the other consider the parameters in the abstract API that are also covered in
RFCs listed above, which leads us to exclude the parameters one of the other RFCs listed above, which leads us to exclude the
RTO.Alpha, RTO.Beta and HB.Max.Burst. For clarity, we also replace parameters RTO.Alpha, RTO.Beta and HB.Max.Burst. For clarity, we
"SETPROTOCOLPARAMETERS" itself with primitives that adjust parameters also replace "SETPROTOCOLPARAMETERS" itself with primitives that
or groups of parameters which fit together. adjust parameters or groups of parameters which fit together.
Initialize: Initialize, described in [RFC4960], creates a local SCTP Initialize: Initialize creates a local SCTP instance that it binds
instance that it binds to a set of local addresses (and, if to a set of local addresses (and, if provided, a local port
provided, port number). Initialize needs to be called only once number) [RFC4960]. Initialize needs to be called only once per
per set of local addresses. [RFC6458] also describes a number of set of local addresses. A number of per-association
per-association initialization parameters that can be used when an initialization parameters can be used when an association is
association is created, but before it is connected (via the created, but before it is connected (via the primitive 'Associate'
primitive 'Associate' below): the maximum number of inbound below): the maximum number of inbound streams the application is
streams the application is prepared to support, the maximum number prepared to support, the maximum number of attempts to be made
of attempts to be made when sending the INIT (the first message of when sending the INIT (the first message of association
association establishment), and the maximum retransmission timeout establishment), and the maximum retransmission timeout (RTO) value
(RTO) value to use when attempting an INIT. At this point, before to use when attempting an INIT [RFC6458]. At this point, before
connecting, an application can also enable UDP encapsulation by connecting, an application can also enable UDP encapsulation by
configuring the remote UDP encapsulation port number [RFC6951]. configuring the remote UDP encapsulation port number [RFC6951].
Associate: This creates an association (the SCTP equivalent of a Associate: This creates an association (the SCTP equivalent of a
connection) that connects the local SCTP instance and a remote connection) that connects the local SCTP instance and a remote
SCTP instance. To identify the remote endpoint, it can be given SCTP instance. To identify the remote endpoint, it can be given
one or multiple (using connectx as described in section 9.9 of one or multiple (using "connectx") sockets (section 9.9 of
[RFC6458]) sockets. Most primitives are associated with a [RFC6458]). Most primitives are associated with a specific
specific association, which is assumed to first have been created. association, which is assumed to first have been created.
Associate can return a list of destination transport addresses so Associate can return a list of destination transport addresses so
that multiple paths can later be used. One of the returned that multiple paths can later be used. One of the returned
sockets will be selected by the local endpoint as default primary sockets will be selected by the local endpoint as default primary
path for sending SCTP packets to this peer, but this choice can be path for sending SCTP packets to this peer, but this choice can be
changed by the application using the list of destination changed by the application using the list of destination
addresses. Associate is also given the number of outgoing streams addresses. Associate is also given the number of outgoing streams
to request and optionally returns the number of negotiated to request and optionally returns the number of negotiated
outgoing streams. An optional parameter of 32 bits, the outgoing streams. An optional parameter of 32 bits, the
adaptation layer indication, can be provided, as specified in adaptation layer indication, can be provided [RFC5061]. If
[RFC5061]. If the extension specified in [RFC4895] is used, the authenticated chunks are used, the chunk types required to be sent
chunk types required to be sent authenticated by the peer can be authenticated by the peer can be provided [RFC4895]. A
provided. [RFC6458] describes a 'SCTP_CANT_STR_ASSOC' 'SCTP_CANT_STR_ASSOC' notification is used to inform the
notification that is used to inform the application of a failure application of a failure to create an association [RFC6458]. An
to create an association. [RFC6458] describes how an application application could use sendto() or sendmsg() to implicitly setup an
could use sendto() or sendmsg() to implicitly setup an
association, thereby handing over a message that SCTP might send association, thereby handing over a message that SCTP might send
during the association setup phase. Note that this mechanism is during the association setup phase [RFC6458]. Note that this
different from TCP's TFO mechanism: the message would arrive only mechanism is different from TCP's TFO mechanism: the message would
once, after at least one RTT, as it is sent together with the arrive only once, after at least one RTT, as it is sent together
third message exchanged during association setup, the COOKIE-ECHO with the third message exchanged during association setup, the
chunk). COOKIE-ECHO chunk).
Send: This sends a message of a certain length in bytes over an Send: This sends a message of a certain length in bytes over an
association. A number can be provided to later refer to the association. A number can be provided to later refer to the
correct message when reporting an error, and a stream id is correct message when reporting an error, and a stream id is
provided to specify the stream to be used inside an association provided to specify the stream to be used inside an association
(we consider this as a mandatory parameter here for simplicity: if (we consider this as a mandatory parameter here for simplicity: if
not provided, the stream id defaults to 0). A condition to not provided, the stream id defaults to 0). A condition to
abandon the message can be specified (for example limiting the abandon the message can be specified (for example limiting the
number of retransmissions or the lifetime of the user message). number of retransmissions or the lifetime of the user message).
This allows to control the partial reliability extension specified This allows to control the partial reliability extension
in [RFC3758] and [RFC7496]. An optional maximum life time can [RFC3758], [RFC7496]. An optional maximum life time can specify
specify the time after which the message should be discarded the time after which the message should be discarded rather than
rather than sent. A choice (advisory, i.e. not guaranteed) of the sent. A choice (advisory, i.e. not guaranteed) of the preferred
preferred path can be made by providing a socket, and the message path can be made by providing a socket, and the message can be
can be delivered out-of-order if the unordered flag is set. An delivered out-of-order if the unordered flag is set. An advisory
advisory flag indicates that the peer should not delay the flag indicates that the peer should not delay the acknowledgement
acknowledgement of the user message provided by making use of the of the user message provided [RFC7053]. Another advisory flag
I-bit specified in [RFC7053]. Another advisory flag indicates indicates whether the application prefers to avoid bundling user
whether the application prefers to avoid bundling user data with data with other outbound DATA chunks (i.e., in the same packet).
other outbound DATA chunks (i.e., in the same packet). A payload A payload protocol-id can be provided to pass a value that
protocol-id can be provided to pass a value that indicates the indicates the type of payload protocol data to the peer. If
type of payload protocol data to the peer. If the extension authenticated chunks are used, the key identifier for
specified in [RFC4895] is used, the key identifier used for authenticating DATA chunks can be provided [RFC4895].
authenticating the DATA chunks can be provided.
Receive: Messages are received from an association, and optionally a Receive: Messages are received from an association, and optionally a
stream within the association, with their size returned. The stream within the association, with their size returned. The
application is notified of the availability of data via a DATA application is notified of the availability of data via a DATA
ARRIVE notification. If the sender has included a payload ARRIVE notification. If the sender has included a payload
protocol-id, this value is also returned. If the received message protocol-id, this value is also returned. If the received message
is only a partial delivery of a whole message, a partial flag will is only a partial delivery of a whole message, a partial flag will
indicate so, in which case the stream id and a stream sequence indicate so, in which case the stream id and a stream sequence
number are provided to the application. A delivery number lets number are provided to the application. A delivery number lets
the application detect reordering. the application detect reordering.
skipping to change at page 13, line 17 skipping to change at page 13, line 29
was aborted. Optionally, an abort reason to be passed to the peer was aborted. Optionally, an abort reason to be passed to the peer
may be provided by the application. A return code informs about may be provided by the application. A return code informs about
success or failure of this procedure. success or failure of this procedure.
Change Heartbeat / Request Heartbeat: This allows the application to Change Heartbeat / Request Heartbeat: This allows the application to
enable/disable heartbeats and optionally specify a heartbeat enable/disable heartbeats and optionally specify a heartbeat
frequency as well as requesting a single heartbeat to be carried frequency as well as requesting a single heartbeat to be carried
out upon a function call, with a notification about success or out upon a function call, with a notification about success or
failure of transmitting the HEARTBEAT chunk to the destination. failure of transmitting the HEARTBEAT chunk to the destination.
Configure Max. Retransmissions of an Association: The parameter Configure Max. Retransmissions of an Association: The parameter Asso
Association.Max.Retrans in [RFC4960], called sasoc_maxrxt in ciation.Max.Retrans [RFC4960] (called "sasoc_maxrxt" in the SCTP
[RFC6458], allows to configure the number of unsuccessful socket API extensions [RFC6458]), allows to configure the number
retransmissions after which an entire association is considered as of unsuccessful retransmissions after which an entire association
failed (which should invoke a COMMUNICATION LOST notification). is considered as failed; this should invoke a COMMUNICATION LOST
notification.
Set Primary: This allows to set a new primary default path for an Set Primary: This allows to set a new primary default path for an
association by providing a socket. Optionally, a default source association by providing a socket. Optionally, a default source
address to be used in IP datagrams can be provided. address to be used in IP datagrams can be provided.
Change Local Address / Set Peer Primary: This allows an endpoint to Change Local Address / Set Peer Primary: This allows an endpoint to
add/remove local addresses to/from an association. In addition, add/remove local addresses to/from an association. In addition,
the peer can be given a hint which address to use as the primary the peer can be given a hint which address to use as the primary
address. This is provided by the protocol extension defined in address [RFC5061].
[RFC5061].
Configure Path Switchover: [RFC4960] contains a primitive called SET Configure Path Switchover: The abstract API contains a primitive
FAILURE THRESHOLD. This configures the parameter called SET FAILURE THRESHOLD [RFC4960]. This configures the
"Path.Max.Retrans", which determines after how many parameter "Path.Max.Retrans", which determines after how many
retransmissions a particular transport address is considered as retransmissions a particular transport address is considered as
unreachable. If there are more transport addresses available in unreachable. If there are more transport addresses available in
an association, reaching this limit will invoke a path switchover. an association, reaching this limit will invoke a path switchover.
[RFC7829] extends this method with a concept of "Potentially An extension called "SCTP-PF" adds a concept of "Potentially
Failed" (PF) paths. When a path is in PF state, SCTP will not Failed" (PF) paths to this method [RFC7829]. When a path is in PF
entirely give up sending on that path, but it will preferably send state, SCTP will not entirely give up sending on that path, but it
data on other active paths if such paths are available. Entering will preferably send data on other active paths if such paths are
the PF state is done upon exceeding a configured maximum number of available. Entering the PF state is done upon exceeding a
retransmissions. Thus, for all paths where this mechanism is configured maximum number of retransmissions. Thus, for all paths
used, there are two configurable error thresholds: one to decide where this mechanism is used, there are two configurable error
that a path is in PF state, and one to decide that the transport thresholds: one to decide that a path is in PF state, and one to
address is unreachable. decide that the transport address is unreachable.
Set / Get Authentication Parameters: This allows an endpoint to add/ Set / Get Authentication Parameters: This allows an endpoint to add/
remove key material to/from an association. In addition, the remove key material to/from an association. In addition, the
chunk types being authenticated can be queried. This is provided chunk types being authenticated can be queried [RFC4895].
by the protocol extension defined in [RFC4895].
Add / Reset Streams, Reset Association: This allows an endpoint to Add / Reset Streams, Reset Association: This allows an endpoint to
add streams to an existing association or or to reset them add streams to an existing association or or to reset them
individually. Additionally, the association can be reset. This individually. Additionally, the association can be reset
is provided by the protocol extension defined in [RFC6525]. [RFC6525].
Status: The 'Status' primitive returns a data block with information Status: The 'Status' primitive returns a data block with information
about a specified association, containing: association connection about a specified association, containing: association connection
state; destination transport address list; destination transport state; destination transport address list; destination transport
address reachability states; current local and peer receiver address reachability states; current local and peer receiver
window sizes; current local congestion window sizes; number of window sizes; current local congestion window sizes; number of
unacknowledged DATA chunks; number of DATA chunks pending receipt; unacknowledged DATA chunks; number of DATA chunks pending receipt;
primary path; most recent SRTT on primary path; RTO on primary primary path; most recent SRTT on primary path; RTO on primary
path; SRTT and RTO on other destination addresses [RFC4960] and path; SRTT and RTO on other destination addresses [RFC4960] and
MTU per path [RFC6458]. MTU per path [RFC6458].
Enable / Disable Interleaving: This allows to enable or disable the Enable / Disable Interleaving: This allows to enable or disable the
negotiation of user message interleaving support for future negotiation of user message interleaving support for future
associations. For existing associations it is possible to query associations. For existing associations it is possible to query
whether user message interleaving support was negotiated or not on whether user message interleaving support was negotiated or not on
a particular association [I-D.ietf-tsvwg-sctp-ndata]. a particular association [I-D.ietf-tsvwg-sctp-ndata].
Set Stream Scheduler: This allows to select a stream scheduler per Set Stream Scheduler: This allows to select a stream scheduler per
association, with a choice of: First Come First Serve, Round association, with a choice of: First Come First Serve, Round
Robin, Round Robin per Packet, Priority Based, Fair Bandwidth, Robin, Round Robin per Packet, Priority Based, Fair Bandwidth,
Weighted Fair Queuing. How these schedulers operate is described Weighted Fair Queuing [I-D.ietf-tsvwg-sctp-ndata].
in detail in [I-D.ietf-tsvwg-sctp-ndata].
Configure Stream Scheduler: This allows to change a parameter per Configure Stream Scheduler: This allows to change a parameter per
stream for the schedulers: a priority value for the Priority Based stream for the schedulers: a priority value for the Priority Based
scheduler and a weight for the Weighted Fair Queuing scheduler. scheduler and a weight for the Weighted Fair Queuing scheduler.
Enable/disable NODELAY: This turns on/off any Nagle-like algorithm Enable/disable NODELAY: This turns on/off any Nagle-like algorithm
for an association [RFC6458]. for an association [RFC6458].
Configure send buffer size: This controls the amount of data SCTP Configure send buffer size: This controls the amount of data SCTP
may have waiting in internal buffers to be sent or retransmitted may have waiting in internal buffers to be sent or retransmitted
skipping to change at page 15, line 12 skipping to change at page 15, line 29
octets, thereby controlling the receiver window for an association octets, thereby controlling the receiver window for an association
[RFC6458]. [RFC6458].
Configure message fragmentation: If a user message causes an SCTP Configure message fragmentation: If a user message causes an SCTP
packet to exceed the maximum fragmentation size (which can be packet to exceed the maximum fragmentation size (which can be
provided by the application, and is otherwise the PMTU size), then provided by the application, and is otherwise the PMTU size), then
the message will be fragmented by SCTP. Disabling message the message will be fragmented by SCTP. Disabling message
fragmentation will produce an error instead of fragmenting the fragmentation will produce an error instead of fragmenting the
message [RFC6458]. message [RFC6458].
Configure Path MTU Discovery: Section 8.1.12 of [RFC6458] explains Configure Path MTU Discovery: Path MTU Discovery can be enabled or
how Path MTU Discovery can be enabled or disabled per peer address disabled per peer address of an association (section 8.1.12 of
of an association. When it is enabled, the current Path MTU value [RFC6458]). When it is enabled, the current Path MTU value can be
can be obtained. When it is disabled, the Path MTU to be used can obtained. When it is disabled, the Path MTU to be used can be
be controlled by the application. controlled by the application.
Configure delayed SACK timer: The time before sending a SACK can be Configure delayed SACK timer: The time before sending a SACK can be
adjusted; delaying SACKs can be disabled; the number of packets adjusted; delaying SACKs can be disabled; the number of packets
that must be received before a SACK is sent without waiting for that must be received before a SACK is sent without waiting for
the delay timer to expire can be configured [RFC6458]. the delay timer to expire can be configured [RFC6458].
Set Cookie life value: The Cookie life value can be adjusted as Set Cookie life value: The Cookie life value can be adjusted
explained in Section 8.1.2 of [RFC6458]. "Valid.Cookie.Life" is (section 8.1.2 of [RFC6458]). "Valid.Cookie.Life" is also one of
also one of the parameters listed as potentially adjustable with the parameters that is potentially adjustable with
SETPROTOCOLPARAMETERS in [RFC4960]. SETPROTOCOLPARAMETERS [RFC4960].
Set maximum burst: The maximum burst of packets that can be emitted Set maximum burst: The maximum burst of packets that can be emitted
by a particular association (default 4, and values above 4 are by a particular association (default 4, and values above 4 are
optional to implement) can be adjusted as explained in Section optional to implement) can be adjusted (section 8.1.2 of
8.1.2 of [RFC6458]. "Max.Burst" is also one of the parameters [RFC6458]). "Max.Burst" is also one of the parameters that is
listed as potentially adjustable with SETPROTOCOLPARAMETERS in potentially adjustable with SETPROTOCOLPARAMETERS [RFC4960].
[RFC4960].
Configure RTO calculation: [RFC4960] lists the following adjustable Configure RTO calculation: The abstract API contains the following
parameters: RTO.Initial; RTO.Min; RTO.Max; RTO.Alpha; RTO.Beta. adjustable parameters: RTO.Initial; RTO.Min; RTO.Max; RTO.Alpha;
Only the initial, minimum and maximum RTO are also described as RTO.Beta. Only the initial, minimum and maximum RTO are also
configurable [RFC6458]. described as configurable in the SCTP sockets API extensions
[RFC6458].
Set DSCP value: Section 8.1.12 of [RFC6458] explains how to set the Set DSCP value: The DSCP value can be set per peer address of an
DSCP value per peer address of an association. association (section 8.1.12 of [RFC6458]).
Set IPv6 flow label: Section 8.1.12 of [RFC6458] explains how to set Set IPv6 flow label: The flow label field can be set per peer
the flow label field per peer address of an association. address of an association (section 8.1.12 of [RFC6458]).
Set Partial Delivery Point: This allows to specify the size of a Set Partial Delivery Point: This allows to specify the size of a
message where partial delivery will be invoked. Setting this to a message where partial delivery will be invoked. Setting this to a
lower value will cause partial deliveries to happen more often lower value will cause partial deliveries to happen more often
[RFC6458]. [RFC6458].
COMMUNICATION UP notification: When a lost communication to an COMMUNICATION UP notification: When a lost communication to an
endpoint is restored or when SCTP becomes ready to send or receive endpoint is restored or when SCTP becomes ready to send or receive
user messages, this notification informs the application process user messages, this notification informs the application process
about the affected association, the type of event that has about the affected association, the type of event that has
skipping to change at page 16, line 24 skipping to change at page 17, line 6
RESTART notification: When SCTP has detected that the peer has RESTART notification: When SCTP has detected that the peer has
restarted, this notification is passed to the upper layer restarted, this notification is passed to the upper layer
[RFC6458]. [RFC6458].
DATA ARRIVE notification: When a message is ready to be retrieved DATA ARRIVE notification: When a message is ready to be retrieved
via the Receive primitive, the application is informed by this via the Receive primitive, the application is informed by this
notification. notification.
SEND FAILURE notification / Receive Unsent Message / Receive SEND FAILURE notification / Receive Unsent Message / Receive
Unacknowledged Message: When a message cannot be delivered via an Unacknowledged Message:
association, the sender can be informed about it and learn whether When a message cannot be delivered via an association, the sender
the message has just not been acknowledged or (e.g. in case of can be informed about it and learn whether the message has just
lifetime expiry) if it has not even been sent. This can also not been acknowledged or (e.g. in case of lifetime expiry) if it
inform the sender that a part of the message has been successfully has not even been sent. This can also inform the sender that a
delivered. part of the message has been successfully delivered.
NETWORK STATUS CHANGE notification: The NETWORK STATUS CHANGE NETWORK STATUS CHANGE notification: The NETWORK STATUS CHANGE
notification informs the application about a socket becoming notification informs the application about a socket becoming
active/inactive [RFC4960] or "Potentially Failed" [RFC7829]. active/inactive [RFC4960] or "Potentially Failed" [RFC7829].
COMMUNICATION LOST notification: When SCTP loses communication to an COMMUNICATION LOST notification: When SCTP loses communication to an
endpoint (e.g. via Heartbeats or excessive retransmission) or endpoint (e.g. via Heartbeats or excessive retransmission) or
detects an abort, this notification informs the application detects an abort, this notification informs the application
process of the affected association and the type of event (failure process of the affected association and the type of event (failure
OR termination in response to a shutdown or abort request). OR termination in response to a shutdown or abort request).
SHUTDOWN COMPLETE notification: When SCTP completes the shutdown SHUTDOWN COMPLETE notification: When SCTP completes the shutdown
procedures, this notification is passed to the upper layer, procedures, this notification is passed to the upper layer,
informing it about the affected assocation. informing it about the affected assocation.
AUTHENTICATION notification: When SCTP wants to notify the upper AUTHENTICATION notification: When SCTP wants to notify the upper
layer regarding the key management related to the extension layer regarding the key management related to authenticated chunks
defined in [RFC4895], this notification is passed to the upper [RFC4895], this notification is passed to the upper layer.
layer.
ADAPTATION LAYER INDICATION notification: When SCTP completes the ADAPTATION LAYER INDICATION notification: When SCTP completes the
association setup and the peer provided an adaptation layer association setup and the peer provided an adaptation layer
indication, this is passed to the upper layer. This extension is indication, this is passed to the upper layer [RFC5061],
defined in [RFC5061] and [RFC6458]. [RFC6458].
STREAM RESET notification: When SCTP completes the procedure for STREAM RESET notification: When SCTP completes the procedure for
resetting streams as specified in [RFC6525], this notification is resetting streams [RFC6525], this notification is passed to the
passed to the upper layer, informing it about the result. upper layer, informing it about the result.
ASSOCIATION RESET notification: When SCTP completes the association ASSOCIATION RESET notification: When SCTP completes the association
reset procedure as specified in [RFC6525], this notification is reset procedure [RFC6525], this notification is passed to the
passed to the upper layer, informing it about the result. upper layer, informing it about the result.
STREAM CHANGE notification: When SCTP completes the procedure used STREAM CHANGE notification: When SCTP completes the procedure used
to increase the number of streams as specified in [RFC6525], this to increase the number of streams [RFC6525], this notification is
notification is passed to the upper layer, informing it about the passed to the upper layer, informing it about the result.
result.
SENDER DRY notification: When SCTP has no more user data to send or SENDER DRY notification: When SCTP has no more user data to send or
retransmit on a particular association, this notification is retransmit on a particular association, this notification is
passed to the upper layer [RFC6458]. passed to the upper layer [RFC6458].
PARTIAL DELIVERY ABORTED notification: When a receiver has begun to PARTIAL DELIVERY ABORTED notification: When a receiver has begun to
receive parts of a user message but the delivery of this message receive parts of a user message but the delivery of this message
is then aborted, this notification is passed to the upper layer is then aborted, this notification is passed to the upper layer
(section 6.1.7 of [RFC6458]). (section 6.1.7 of [RFC6458]).
skipping to change at page 17, line 47 skipping to change at page 18, line 33
optionally be passed to the application (e.g., identification to optionally be passed to the application (e.g., identification to
retrieve unsent and unacknowledged data). SCTP "can invoke" a retrieve unsent and unacknowledged data). SCTP "can invoke" a
COMMUNICATION ERROR notification and "may send" a RESTART COMMUNICATION ERROR notification and "may send" a RESTART
notification, making these two notifications optional to implement. notification, making these two notifications optional to implement.
The list provided under 'Status' includes "etc", indicating that more The list provided under 'Status' includes "etc", indicating that more
information could be provided. The primitive 'Get SRTT Report' information could be provided. The primitive 'Get SRTT Report'
returns information that is included in the information that 'Status' returns information that is included in the information that 'Status'
provides and is therefore not discussed. The 'Destroy SCTP Instance' provides and is therefore not discussed. The 'Destroy SCTP Instance'
API function was excluded: it erases the SCTP instance that was API function was excluded: it erases the SCTP instance that was
created by 'Initialize', but is not a Primitive as defined in this created by 'Initialize', but is not a Primitive as defined in this
document because it does not relate to a Transport Feature. The document because it does not relate to a transport feature. The
SHUTDOWN EVENT described in Section 6.1 of [RFC6458] informs an SHUTDOWN EVENT informs an application that the peer has sent a
application that the peer has sent a SHUTDOWN, and hence no further SHUTDOWN, and hence no further data should be sent on this socket
data should be sent on this socket. However, if an application would (section 6.1 of [RFC6458]). However, if an application would try to
try to send data on the socket, it would get an error message anyway; send data on the socket, it would get an error message anyway; thus,
thus, this event is classified as "just affecting the application this event is classified as "just affecting the application
programming style, not how the underlying protocol operates" and not programming style, not how the underlying protocol operates" and not
included here. included here.
3.4. Primitives Provided by UDP and UDP-Lite 3.4. Primitives Provided by UDP and UDP-Lite
The primitives provided by UDP and UDP-Lite are described in [FJ16]. The initial UDP specification [RFC0768] states: "This User Datagram
Protocol (UDP) is defined to make available a datagram mode of
packet-switched computer communication in the environment of an
interconnected set of computer networks." It "provides a procedure
for application programs to send messages to other programs with a
minimum of protocol mechanism (..)".
The User Interface section of RFC768 states that the user interface
to an application should be able to create receive, source and
destination ports and addresses, and provide operations to receive
data based on ports with an indication of source port and address.
Operations should be provided that allow datagrams be sent specifying
the source and destination ports and addresses to be sent.
UDP offers only a basic transport interface. UDP datagrams may be
directly sent and received, without exchanging messages between the
endpoints to setup a connection (i.e., no handshake is performed by
the transport protocol prior to communication). Neither UDP nor UDP-
Lite provide congestion control, retransmission, nor do they have
support to optimise fragmentation and other transport functions.
This means that applications using UDP need to provide additional
functions on top of the UDP transport API [RFC8085]. Guidance on the
use of the services provided by UDP is provided in the UDP Guidelines
[RFC8085].
The set of pass 1 primitives for UDP and UDP-Lite is documented in
[FJ16].
3.5. The service of LEDBAT 3.5. The service of LEDBAT
The service of the Low Extra Delay Background Transport (LEDBAT) The service of the Low Extra Delay Background Transport (LEDBAT)
congestion control mechanism is described in the abstract of congestion control mechanism is described as follows: "LEDBAT is
[RFC6817] as follows: "LEDBAT is designed for use by background bulk- designed for use by background bulk-transfer applications to be no
transfer applications to be no more aggressive than standard TCP more aggressive than standard TCP congestion control (as specified in
congestion control (as specified in RFC 5681) and to yield in the RFC 5681) and to yield in the presence of competing flows, thus
presence of competing flows, thus limiting interference with the limiting interference with the network performance of competing
network performance of competing flows." flows" [RFC6817].
LEDBAT does not have any primitives, as LEDBAT is not a transport LEDBAT does not have any primitives, as LEDBAT is not a transport
protocol. [RFC6817] states: "LEDBAT can be used as part of a protocol. According to its specification [RFC6817], "LEDBAT can be
transport protocol or as part of an application, as long as the data used as part of a transport protocol or as part of an application, as
transmission mechanisms are capable of carrying timestamps and long as the data transmission mechanisms are capable of carrying
acknowledging data frequently. LEDBAT can be used with TCP, Stream timestamps and acknowledging data frequently. LEDBAT can be used
Control Transmission Protocol (SCTP), and Datagram Congestion Control with TCP, Stream Control Transmission Protocol (SCTP), and Datagram
Protocol (DCCP), with appropriate extensions where necessary; and it Congestion Control Protocol (DCCP), with appropriate extensions where
can be used with proprietary application protocols, such as those necessary; and it can be used with proprietary application protocols,
built on top of UDP for peer-to- peer (P2P) applications." At the such as those built on top of UDP for peer-to- peer (P2P)
time of writing, the appropriate extensions for TCP, SCTP or DCCP do applications." At the time of writing, the appropriate extensions
not exist. for TCP, SCTP or DCCP do not exist.
A numer of configurable parameters exist in the LEDBAT specification: A numer of configurable parameters exist in the LEDBAT specification:
TARGET, which is the queuing delay target at which LEDBAT tries to TARGET, which is the queuing delay target at which LEDBAT tries to
operate, must be set to 100ms or less. ALLOWED_INCREASE (should be operate, must be set to 100ms or less. ALLOWED_INCREASE (should be
1, must be greater than 0) limits the speed at which LEDBAT increases 1, must be greater than 0) limits the speed at which LEDBAT increases
its rate. GAIN, which MUST be set to 1 or less to avoid a faster its rate. GAIN, which MUST be set to 1 or less to avoid a faster
ramp-up than TCP Reno, determines how quickly the sender responds to ramp-up than TCP Reno, determines how quickly the sender responds to
changes in queueing delay. Implementations may divide GAIN into two changes in queueing delay. Implementations may divide GAIN into two
parameters, one for increase and a possibly larger one for decrease. parameters, one for increase and a possibly larger one for decrease.
We call these parameters GAIN_INC and GAIN_DEC here. BASE_HISTORY is We call these parameters GAIN_INC and GAIN_DEC here. BASE_HISTORY is
the size of the list of measured base delays, and SHOULD be 10. This the size of the list of measured base delays, and SHOULD be 10. This
list can be filtered using a FILTER() function which is not list can be filtered using a FILTER() function which is not
prescribed in [RFC6817], yielding a list of size CURRENT_FILTER. The prescribed [RFC6817], yielding a list of size CURRENT_FILTER. The
initial and minimum congestion windows, INIT_CWND and MIN_CWND, initial and minimum congestion windows, INIT_CWND and MIN_CWND,
should both be 2. should both be 2.
Regarding which of these parameters should be under control of an Regarding which of these parameters should be under control of an
application, the possible range goes from exposing nothing on the one application, the possible range goes from exposing nothing on the one
hand, to considering everything that is not fully prescribed with a hand, to considering everything that is not prescribed with a MUST in
MUST in [RFC6817] as a parameter on the other hand. Function the specification as a parameter on the other hand. Function
implementations are not provided as a parameter to any of the implementations are not provided as a parameter to any of the
transport protocols discussed here, and hence we do not regard the transport protocols discussed here, and hence we do not regard the
FILTER() function as a parameter. However, to avoid unnecessarily FILTER() function as a parameter. However, to avoid unnecessarily
limiting future implementations, we consider all other parameters limiting future implementations, we consider all other parameters
above as tunable parameters that should be exposed. above as tunable parameters that should be exposed.
4. Pass 2 4. Pass 2
This pass categorizes the primitives from pass 1 based on whether This pass categorizes the primitives from pass 1 based on whether
they relate to a connection or to data transmission. Primitives are they relate to a connection or to data transmission. Primitives are
skipping to change at page 19, line 33 skipping to change at page 20, line 49
concept and use it to refer to, e.g., TCP connections (identifiable concept and use it to refer to, e.g., TCP connections (identifiable
by a unique pair of IP addresses and TCP port numbers), SCTP by a unique pair of IP addresses and TCP port numbers), SCTP
associations (identifiable by multiple IP address and port number associations (identifiable by multiple IP address and port number
pairs), as well UDP and UDP-Lite connections (identifiable by a pairs), as well UDP and UDP-Lite connections (identifiable by a
unique socket pair). unique socket pair).
Some minor details are omitted for the sake of generalization -- Some minor details are omitted for the sake of generalization --
e.g., SCTP's 'close' [RFC4960] returns success or failure, and lets e.g., SCTP's 'close' [RFC4960] returns success or failure, and lets
the application control whether further receive or send operations or the application control whether further receive or send operations or
both are disabled [RFC6458]. This is not described in the same way both are disabled [RFC6458]. This is not described in the same way
for TCP in [RFC0793], but these details play no significant role for for TCP [RFC0793], but these details play no significant role for the
the primitives provided by either TCP or SCTP (for the sake of being primitives provided by either TCP or SCTP (for the sake of being
generic, it could be assumed that both receive and send operations generic, it could be assumed that both receive and send operations
are disabled in both cases). are disabled in both cases).
The TCP 'send' and 'receive' primitives include usage of an "URGENT" The TCP 'send' and 'receive' primitives include usage of an "URGENT"
mechanism. This mechanism is required to implement the "synch mechanism. This mechanism is required to implement the "synch
signal" used by telnet [RFC0854], but SHOULD NOT be used by new signal" used by telnet [RFC0854], but SHOULD NOT be used by new
applications [RFC6093]. Because pass 2 is meant as a basis for the applications [RFC6093]. Because pass 2 is meant as a basis for the
creation of future systems, the "URGENT" mechanism is excluded. This creation of future systems, the "URGENT" mechanism is excluded. This
also concerns the notification "Urgent pointer advance" in the also concerns the notification "Urgent pointer advance" in the
ERROR_REPORT described in Section 4.2.4.1 of [RFC1122]. ERROR_REPORT (section 4.2.4.1 of [RFC1122]).
Since LEDBAT is a congestion control mechanism and not a protocol, it Since LEDBAT is a congestion control mechanism and not a protocol, it
is not currently defined when to enable / disable or configure the is not currently defined when to enable / disable or configure the
mechanism. For instance, it could be a one-time choice upon mechanism. For instance, it could be a one-time choice upon
connection establishment or when listening for incoming connections, connection establishment or when listening for incoming connections,
in which case it should be categorized under CONNECTION.ESTABLISHMENT in which case it should be categorized under CONNECTION.ESTABLISHMENT
or CONNECTION.AVAILABILITY, respectively. To avoid unnecessarily or CONNECTION.AVAILABILITY, respectively. To avoid unnecessarily
limiting future implementations, it was decided to place it under limiting future implementations, it was decided to place it under
CONNECTION.MAINTENANCE, with all parameters that are described in CONNECTION.MAINTENANCE, with all parameters that are described in the
[RFC6817] made configurable. specification [RFC6817] made configurable.
4.1. CONNECTION Related Primitives 4.1. CONNECTION Related Primitives
ESTABLISHMENT: ESTABLISHMENT:
Active creation of a connection from one transport endpoint to one or Active creation of a connection from one transport endpoint to one or
more transport endpoints. more transport endpoints.
Interfaces to UDP and UDP-Lite allow both connection-oriented and Interfaces to UDP and UDP-Lite allow both connection-oriented and
connection-less usage of the API . [RFC8085] connection-less usage of the API [RFC8085].
o CONNECT.TCP: o CONNECT.TCP:
Pass 1 primitive / event: 'open' (active) or 'open' (passive) with Pass 1 primitive / event: 'open' (active) or 'open' (passive) with
socket, followed by 'send' socket, followed by 'send'
Parameters: 1 local IP address (optional); 1 destination transport Parameters: 1 local IP address (optional); 1 destination transport
address (for active open; else the socket and the local IP address address (for active open; else the socket and the local IP address
of the succeeding incoming connection request will be maintained); of the succeeding incoming connection request will be maintained);
timeout (optional); options (optional); MKT configuration timeout (optional); options (optional); MKT configuration
(optional); user message (optional) (optional); user message (optional)
Comments: If the local IP address is not provided, a default Comments: If the local IP address is not provided, a default
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o STATUS.MPTCP: o STATUS.MPTCP:
Pass 1 primitive / event: not specified Pass 1 primitive / event: not specified
Returns: list of pairs of tuples of IP address and TCP port number Returns: list of pairs of tuples of IP address and TCP port number
of each subflow. The first of the pair is the local IP and port of each subflow. The first of the pair is the local IP and port
number, while the second is the remote IP and port number. number, while the second is the remote IP and port number.
o SET_DSCP.TCP: o SET_DSCP.TCP:
Pass 1 primitive / event: not specified Pass 1 primitive / event: not specified
Parameters: DSCP value Parameters: DSCP value
Comments: this allows an application to change the DSCP value for Comments: this allows an application to change the DSCP value for
outgoing segments. For TCP this was originally specified for the outgoing segments.
TOS field [RFC1122], which is here interpreted to refer to the
DSField [RFC3260].
o SET_DSCP.SCTP: o SET_DSCP.SCTP:
Pass 1 primitive / event: 'Set DSCP value' Pass 1 primitive / event: 'Set DSCP value'
Parameters: DSCP value Parameters: DSCP value
Comments: this allows an application to change the DSCP value for Comments: this allows an application to change the DSCP value for
outgoing packets on a path. outgoing packets on a path.
o SET_DSCP.UDP(-Lite): o SET_DSCP.UDP(-Lite):
Pass 1 primitive / event: 'SET_DSCP' Pass 1 primitive / event: 'SET_DSCP'
Parameter: DSCP value Parameter: DSCP value
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o ERROR.TCP: o ERROR.TCP:
Pass 1 primitive / event: 'ERROR_REPORT' Pass 1 primitive / event: 'ERROR_REPORT'
Returns: reason (encoding not specified); subreason (encoding not Returns: reason (encoding not specified); subreason (encoding not
specified) specified)
Comments: soft errors that can be ignored without harm by many Comments: soft errors that can be ignored without harm by many
applications; an application should be able to disable these applications; an application should be able to disable these
notifications. The reported conditions include at least: ICMP notifications. The reported conditions include at least: ICMP
error message arrived; Excessive Retransmissions. error message arrived; Excessive Retransmissions.
o ERROR.UDP(-Lite): o ERROR.UDP(-Lite):
Pass 1 primitive / event: 'ERROR_REPORT'. Pass 1 primitive / event: 'ERROR_REPORT'
Returns: Error report Returns: Error report
Comments: This returns soft errors that may be ignored without Comments: This returns soft errors that may be ignored without
harm by many applications; An application must connect to be able harm by many applications; An application must connect to be able
receive these notifications. receive these notifications.
o SET_AUTH.TCP: o SET_AUTH.TCP:
Pass 1 primitive / event: 'send' Pass 1 primitive / event: not specified
Parameters: current_key, rnext_key Parameters: current_key, rnext_key
Comments: current_key and rnext_key are the preferred outgoing MKT Comments: current_key and rnext_key are the preferred outgoing MKT
and the preferred incoming MKT, respectively, for a segment that and the preferred incoming MKT, respectively, for a segment that
is sent on an active option. is sent on the connection.
o SET_AUTH.SCTP: o SET_AUTH.SCTP:
Pass 1 primitive / event: 'Set / Get Authentication Parameters' Pass 1 primitive / event: 'Set / Get Authentication Parameters'
Parameters: key_id, key, hmac_id Parameters: key_id, key, hmac_id
o GET_AUTH.TCP: o GET_AUTH.TCP:
Pass 1 primitive / event: 'receive' Pass 1 primitive / event: not specified
Parameters: current_key, rnext_key Parameters: current_key, rnext_key
Comments: current_key and rnext_key are the preferred outgoing MKT Comments: current_key and rnext_key are the preferred outgoing MKT
and the preferred incoming MKT, respectively, that were carried on and the preferred incoming MKT, respectively, that were carried on
a recently received segment. a recently received segment.
o GET_AUTH.SCTP: o GET_AUTH.SCTP:
Pass 1 primitive / event: 'Set / Get Authentication Parameters' Pass 1 primitive / event: 'Set / Get Authentication Parameters'
Parameters: key_id, chunk_list Parameters: key_id, chunk_list
o RESET_STREAM.SCTP: o RESET_STREAM.SCTP:
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Parameters: sid, direction Parameters: sid, direction
o RESET_STREAM-EVENT.SCTP: o RESET_STREAM-EVENT.SCTP:
Pass 1 primitive / event: 'STREAM RESET notification' Pass 1 primitive / event: 'STREAM RESET notification'
Parameters: information about the result of RESET_STREAM.SCTP. Parameters: information about the result of RESET_STREAM.SCTP.
Comments: This is issued when the procedure for resetting streams Comments: This is issued when the procedure for resetting streams
has completed. has completed.
o RESET_ASSOC.SCTP: o RESET_ASSOC.SCTP:
Pass 1 primitive / event: 'Add / Reset Streams, Reset Association' Pass 1 primitive / event: 'Add / Reset Streams, Reset Association'
Parameters: information related to the extension defined in Parameters: information related to the extension, defined in
[RFC3260]. [RFC3260].
o RESET_ASSOC-EVENT.SCTP: o RESET_ASSOC-EVENT.SCTP:
Pass 1 primitive / event: 'ASSOCIATION RESET notification' Pass 1 primitive / event: 'ASSOCIATION RESET notification'
Parameters: information about the result of RESET_ASSOC.SCTP. Parameters: information about the result of RESET_ASSOC.SCTP.
Comments: This is issued when the procedure for resetting an Comments: This is issued when the procedure for resetting an
association has completed. association has completed.
o ADD_STREAM.SCTP: o ADD_STREAM.SCTP:
Pass 1 primitive / event: 'Add / Reset Streams, Reset Association' Pass 1 primitive / event: 'Add / Reset Streams, Reset Association'
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Parameters: max burst value Parameters: max burst value
Comments: not all implementations allow values above the default Comments: not all implementations allow values above the default
of 4. of 4.
o SET_PARTIAL_DELIVERY_POINT.SCTP: o SET_PARTIAL_DELIVERY_POINT.SCTP:
Pass 1 primitive / event: 'Set Partial Delivery Point' Pass 1 primitive / event: 'Set Partial Delivery Point'
Parameters: partial delivery point (integer) Parameters: partial delivery point (integer)
Comments: this parameter must be smaller or equal to the socket Comments: this parameter must be smaller or equal to the socket
receive buffer size. receive buffer size.
o CHECKSUM.UDP: o SET_CHECKSUM_ENABLED.UDP:
Pass 1 primitive / event: 'DISABLE_CHECKSUM'. Pass 1 primitive / event: 'CHECKSUM_ENABLED'.
Parameters: 0 when no checksum is used at sender, 1 for checksum Parameters: 0 when zero checksum is used at sender, 1 for checksum
at sender (default) at sender (default)
o CHECKSUM_REQUIRED.UDP: o SET_CHECKSUM_REQUIRED.UDP:
Pass 1 primitive / event: 'REQUIRE_CHECKSUM'. Pass 1 primitive / event: 'REQUIRE_CHECKSUM'.
Parameter: 0 when checksum is required at receiver, 1 to allow Parameter: 0 to allow zero checksum, 1 when a non-zero checksum is
zero checksum at receiver (default) required (default) at receiver
o SET_CHECKSUM_COVERAGE.UDP-Lite: o SET_CHECKSUM_COVERAGE.UDP-Lite:
Pass 1 primitive / event: 'SET_CHECKSUM_COVERAGE' Pass 1 primitive / event: 'SET_CHECKSUM_COVERAGE'
Parameters: Coverage length at sender (default maximum coverage) Parameters: Coverage length at sender (default maximum coverage)
o SET_MIN_CHECKSUM_COVERAGE.UDP-Lite: o SET_MIN_CHECKSUM_COVERAGE.UDP-Lite:
Pass 1 primitive / event: 'SET_MIN_COVERAGE'. Pass 1 primitive / event: 'SET_MIN_COVERAGE'.
Parameter: Coverage length at receiver (default minimum coverage) Parameter: Coverage length at receiver (default minimum coverage)
o SET_DF.UDP(-Lite): o SET_DF.UDP(-Lite):
Pass 1 primitive event: 'SET_DF'. Pass 1 primitive event: 'SET_DF'.
Parameter: 0 when DF is not set (default), 1 when DF is set Parameter: 0 when DF is not set (default) in the IPv4 header, 1
when DF is set
o GET_MMS_S.UDP(-Lite):
Pass 1 primitive event: 'GET_MMS_S'.
Comments: this retrieves the maximum transport-message size that
may be sent using a non-fragmented IP packet from the configured
interface.
o GET_MMS_R.UDP(-Lite):
Pass 1 primitive event: 'GET_MMS_R'.
Comments: this retrieves the maximum transport-message size that
may be received from the configured interface.
o SET_TTL.UDP(-Lite) (IPV6_UNICAST_HOPS): o SET_TTL.UDP(-Lite) (IPV6_UNICAST_HOPS):
Pass 1 primitive / event: 'SET_TTL' and 'SET_IPV6_UNICAST_HOPS' Pass 1 primitive / event: 'SET_TTL' and 'SET_IPV6_UNICAST_HOPS'
Parameters: IPv4 TTL value or IPv6 Hop Count value Parameters: IPv4 TTL value or IPv6 Hop Count value
Comments: This allows an application to change the IPv4 TTL of Comments: This allows an application to change the IPv4 TTL of
IPv6 Hop count value for outgoing UDP(-Lite) datagrams. IPv6 Hop count value for outgoing UDP(-Lite) datagrams.
o GET_TTL.UDP(-Lite) (IPV6_UNICAST_HOPS): o GET_TTL.UDP(-Lite) (IPV6_UNICAST_HOPS):
Pass 1 primitive / event: 'GET_TTL' and 'GET_IPV6_UNICAST_HOPS' Pass 1 primitive / event: 'GET_TTL' and 'GET_IPV6_UNICAST_HOPS'
Returns: IPv4 TTL value or IPv6 Hop Count value Returns: IPv4 TTL value or IPv6 Hop Count value
Comments: This allows an application to read the the IPv4 TTL of Comments: This allows an application to read the the IPv4 TTL of
IPv6 Hop count value from a received UDP(-Lite) datagram. IPv6 Hop count value from a received UDP(-Lite) datagram.
o SET_ECN.UDP(-Lite): o SET_ECN.UDP(-Lite):
Pass 1 primitive / event: 'SET_ECN' Pass 1 primitive / event: 'SET_ECN'
Parameters: ECN value Parameters: ECN value
Comments: This allows a UDP(-Lite) application to set the ECN Comments: This allows a UDP(-Lite) application to set the ECN
codepoint field for outgoing UDP(-Lite) datagrams. codepoint field for outgoing UDP(-Lite) datagrams. Defaults to
sending '00'.
o GET_ECN.UDP(-Lite): o GET_ECN.UDP(-Lite):
Pass 1 primitive / event: 'GET_ECN' Pass 1 primitive / event: 'GET_ECN'
Parameters: ECN value Parameters: ECN value
Comments: This allows a UDP(-Lite) application to read the ECN Comments: This allows a UDP(-Lite) application to read the ECN
codepoint field from a received UDP(-Lite) datagram. codepoint field from a received UDP(-Lite) datagram.
o SET_IP_OPTIONS.UDP(-Lite): o SET_IP_OPTIONS.UDP(-Lite):
Pass 1 primitive / event: 'SET_IP_OPTIONS' Pass 1 primitive / event: 'SET_IP_OPTIONS'
Parameters: options Parameters: options
skipping to change at page 30, line 47 skipping to change at page 35, line 11
o ABORT.SCTP: o ABORT.SCTP:
Pass 1 primitive / event: 'abort' Pass 1 primitive / event: 'abort'
Parameters: abort reason to be given to the peer (optional) Parameters: abort reason to be given to the peer (optional)
Comments: this terminates a connection without delivering Comments: this terminates a connection without delivering
remaining data and sends an error message to the other side. remaining data and sends an error message to the other side.
o ABORT.UDP(-Lite): o ABORT.UDP(-Lite):
Pass 1 primitive event: 'CLOSE' Pass 1 primitive event: 'CLOSE'
Comments: this terminates a connection without delivering Comments: this terminates a connection without delivering
remaining data. No further UDP(-Lite) datagrams are sent/received remaining data. No further UDP(-Lite) datagrams are sent/received
on this connection. for this transport service instance.
o TIMEOUT.TCP: o TIMEOUT.TCP:
Pass 1 primitive / event: 'USER TIMEOUT' event Pass 1 primitive / event: 'USER TIMEOUT' event
Comments: the application is informed that the connection is Comments: the application is informed that the connection is
aborted. This event is executed on expiration of the timeout set aborted. This event is executed on expiration of the timeout set
in CONNECTION.ESTABLISHMENT.CONNECT.TCP (possibly adjusted in in CONNECTION.ESTABLISHMENT.CONNECT.TCP (possibly adjusted in
CONNECTION.MAINTENANCE.CHANGE_TIMEOUT.TCP). CONNECTION.MAINTENANCE.CHANGE_TIMEOUT.TCP).
o TIMEOUT.SCTP: o TIMEOUT.SCTP:
Pass 1 primitive / event: 'COMMUNICATION LOST' event Pass 1 primitive / event: 'COMMUNICATION LOST' event
Comments: the application is informed that the connection is Comments: the application is informed that the connection is
aborted. this event is executed on expiration of the timeout that aborted. this event is executed on expiration of the timeout that
should be enabled by default (see beginning of section 8.3 in should be enabled by default (see the beginning of section 8.3 in
[RFC4960]) and was possibly adjusted in [RFC4960]) and was possibly adjusted in
CONNECTION.MAINTENANCE.CHANGE_TIMEOOUT.SCTP. CONNECTION.MAINTENANCE.CHANGE_TIMEOOUT.SCTP.
o ABORT-EVENT.TCP: o ABORT-EVENT.TCP:
Pass 1 primitive / event: not specified. Pass 1 primitive / event: not specified.
o ABORT-EVENT.SCTP: o ABORT-EVENT.SCTP:
Pass 1 primitive / event: 'COMMUNICATION LOST' event Pass 1 primitive / event: 'COMMUNICATION LOST' event
Returns: abort reason from the peer (if available) Returns: abort reason from the peer (if available)
Comments: the application is informed that the other side has Comments: the application is informed that the other side has
skipping to change at page 34, line 7 skipping to change at page 39, line 7
Comments: This informs the application that the stack has no more Comments: This informs the application that the stack has no more
user data to send. user data to send.
o PARTIAL_DELIVERY_ABORTED-EVENT.SCTP: o PARTIAL_DELIVERY_ABORTED-EVENT.SCTP:
Pass 1 primitive / event: 'PARTIAL DELIVERY ABORTED' notification Pass 1 primitive / event: 'PARTIAL DELIVERY ABORTED' notification
Comments: This informs the receiver of a partial message that the Comments: This informs the receiver of a partial message that the
further delivery of the message has been aborted. further delivery of the message has been aborted.
5. Pass 3 5. Pass 3
This section presents the superset of all Transport Features in all This section presents the superset of all transport features in all
protocols that were discussed in the preceding sections, based on the protocols that were discussed in the preceding sections, based on the
list of primitives in pass 2 but also on text in pass 1 to include list of primitives in pass 2 but also on text in pass 1 to include
features that can be configured in one protocol and are static transport features that can be configured in one protocol and are
properties in another (congestion control, for example). Again, some static properties in another (congestion control, for example).
minor details are omitted for the sake of generalization -- e.g., TCP Again, some minor details are omitted for the sake of generalization
may provide various different IP options, but only source route is -- e.g., TCP may provide various different IP options, but only
mandatory to implement, and this detail is not visible in the Pass 3 source route is mandatory to implement, and this detail is not
feature "Specify IP Options". visible in the Pass 3 transport feature "Specify IP Options".
5.1. CONNECTION Related Transport Features 5.1. CONNECTION Related Transport Features
ESTABLISHMENT: ESTABLISHMENT:
Active creation of a connection from one transport endpoint to one or Active creation of a connection from one transport endpoint to one or
more transport endpoints. more transport endpoints.
o Connect o Connect
Protocols: TCP, SCTP, UDP(-Lite) Protocols: TCP, SCTP, UDP(-Lite)
o Specify which IP Options must always be used o Specify which IP Options must always be used
Protocols: TCP Protocols: TCP, UDP(-Lite)
o Request multiple streams o Request multiple streams
Protocols: SCTP Protocols: SCTP
o Limit the number of inbound streams o Limit the number of inbound streams
Protocols: SCTP Protocols: SCTP
o Specify number of attempts and/or timeout for the first o Specify number of attempts and/or timeout for the first
establishment message establishment message
Protocols: TCP, SCTP Protocols: TCP, SCTP
skipping to change at page 35, line 28 skipping to change at page 41, line 6
o Enable UDP encapsulation with a specified remote UDP port number o Enable UDP encapsulation with a specified remote UDP port number
Protocols: SCTP Protocols: SCTP
AVAILABILITY: AVAILABILITY:
Preparing to receive incoming connection requests. Preparing to receive incoming connection requests.
o Listen, 1 specified local interface o Listen, 1 specified local interface
Protocols: TCP, SCTP, UDP(-Lite) Protocols: TCP, SCTP, UDP(-Lite)
o Listen, N specified local interfaces o Listen, N specified local interfaces
Protocols: SCTP, UDP(-Lite) Protocols: SCTP
o Listen, all local interfaces o Listen, all local interfaces
Protocols: TCP, SCTP, UDP(-Lite) Protocols: TCP, SCTP, UDP(-Lite)
o Obtain requested number of streams o Obtain requested number of streams
Protocols: SCTP Protocols: SCTP
o Limit the number of inbound streams o Limit the number of inbound streams
Protocols: SCTP Protocols: SCTP
o Specify which IP Options must always be used o Specify which IP Options must always be used
Protocols: TCP Protocols: TCP, UDP(-Lite)
o Disable MPTCP o Disable MPTCP
Protocols: MPTCP Protocols: MPTCP
o Configure authentication o Configure authentication
Protocols: TCP, SCTP Protocols: TCP, SCTP
Comments: With TCP, this allows to configure Master Key Tuples Comments: With TCP, this allows to configure Master Key Tuples
(MKTs). In SCTP, this allows to specify which chunk types must (MKTs). In SCTP, this allows to specify which chunk types must
always be authenticated. DATA, ACK etc. are different 'chunks' in always be authenticated. DATA, ACK etc. are different 'chunks' in
SCTP; one or more chunks may be included in a single packet. SCTP; one or more chunks may be included in a single packet.
skipping to change at page 38, line 47 skipping to change at page 46, line 8
o Specify checksum coverage used by the sender o Specify checksum coverage used by the sender
Protocols: UDP-Lite Protocols: UDP-Lite
o Specify minimum checksum coverage required by receiver o Specify minimum checksum coverage required by receiver
Protocols: UDP-Lite Protocols: UDP-Lite
o Specify DF field o Specify DF field
Protocols: UDP(-Lite) Protocols: UDP(-Lite)
o Get max. transport-message size that may be sent using a non-
fragmented IP packet from the configured interface
Protocols: UDP(-Lite)
o Get max. transport-message size that may be received from the
configured interface
Protocols: UDP(-Lite)
o Specify TTL/Hop count field o Specify TTL/Hop count field
Protocols: UDP(-Lite) Protocols: UDP(-Lite)
o Obtain TTL/Hop count field o Obtain TTL/Hop count field
Protocols: UDP(-Lite) Protocols: UDP(-Lite)
o Specify ECN field o Specify ECN field
Protocols: UDP(-Lite) Protocols: UDP(-Lite)
o Obtain ECN field o Obtain ECN field
skipping to change at page 40, line 7 skipping to change at page 47, line 36
Protocols: UDP(-Lite) Protocols: UDP(-Lite)
o Timeout event when data could not be delivered for too long o Timeout event when data could not be delivered for too long
Protocols: TCP, SCTP Protocols: TCP, SCTP
Comments: the timeout is configured with CONNECTION.MAINTENANCE Comments: the timeout is configured with CONNECTION.MAINTENANCE
"Change timeout for aborting connection (using retransmit limit or "Change timeout for aborting connection (using retransmit limit or
time value)". time value)".
5.2. DATA Transfer Related Transport Features 5.2. DATA Transfer Related Transport Features
All features in this section refer to an existing connection, i.e. a All transport features in this section refer to an existing
connection that was either established or made available for connection, i.e. a connection that was either established or made
receiving data. Note that TCP allows to transfer data (a single available for receiving data. Note that TCP allows to transfer data
optional user message, possibly arriving multiple times) before the (a single optional user message, possibly arriving multiple times)
connection is fully established. Reliable data transfer entails before the connection is fully established. Reliable data transfer
delay -- e.g. for the sender to wait until it can transmit data, or entails delay -- e.g. for the sender to wait until it can transmit
due to retransmission in case of packet loss. data, or due to retransmission in case of packet loss.
5.2.1. Sending Data 5.2.1. Sending Data
All features in this section are provided by DATA.SEND from pass 2. All transport features in this section are provided by DATA.SEND from
DATA.SEND is given a data block from the application, which we here pass 2. DATA.SEND is given a data block from the application, which
call a "message" if the beginning and end of the data block can be we here call a "message" if the beginning and end of the data block
identified at the receiver, and "data" otherwise. can be identified at the receiver, and "data" otherwise.
o Reliably transfer data, with congestion control o Reliably transfer data, with congestion control
Protocols: TCP Protocols: TCP
o Reliably transfer a message, with congestion control o Reliably transfer a message, with congestion control
Protocols: SCTP Protocols: SCTP
o Unreliably transfer a message, with congestion control o Unreliably transfer a message, with congestion control
Protocols: SCTP Protocols: SCTP
skipping to change at page 41, line 13 skipping to change at page 49, line 21
Protocols: SCTP Protocols: SCTP
o Specifying a key id to be used to authenticate a message o Specifying a key id to be used to authenticate a message
Protocols: SCTP Protocols: SCTP
o Request not to delay the acknowledgement (SACK) of a message o Request not to delay the acknowledgement (SACK) of a message
Protocols: SCTP Protocols: SCTP
5.2.2. Receiving Data 5.2.2. Receiving Data
All features in this section are provided by DATA.RECEIVE from pass All transport features in this section are provided by DATA.RECEIVE
2. DATA.RECEIVE fills a buffer provided by the application, with from pass 2. DATA.RECEIVE fills a buffer provided by the
what we here call a "message" if the beginning and end of the data application, with what we here call a "message" if the beginning and
block can be identified at the receiver, and "data" otherwise. end of the data block can be identified at the receiver, and "data"
otherwise.
o Receive data (with no message delineation) o Receive data (with no message delineation)
Protocols: TCP Protocols: TCP
o Receive a message o Receive a message
Protocols: SCTP, UDP(-Lite) Protocols: SCTP, UDP(-Lite)
o Choice of stream to receive from o Choice of stream to receive from
Protocols: SCTP Protocols: SCTP
skipping to change at page 42, line 19 skipping to change at page 51, line 6
been aborted been aborted
Protocols: SCTP Protocols: SCTP
6. Acknowledgements 6. Acknowledgements
The authors would like to thank (in alphabetical order) Bob Briscoe, The authors would like to thank (in alphabetical order) Bob Briscoe,
David Hayes, Karen Nielsen, Joe Touch and Brian Trammell for David Hayes, Karen Nielsen, Joe Touch and Brian Trammell for
providing valuable feedback on this document. We especially thank providing valuable feedback on this document. We especially thank
Christoph Paasch for providing input related to Multipath TCP, and Christoph Paasch for providing input related to Multipath TCP, and
Gorry Fairhurst and Tom Jones for providing input related to UDP(- Gorry Fairhurst and Tom Jones for providing input related to UDP(-
Lite), via [FJ16]. This work has received funding from the European Lite). This work has received funding from the European Union's
Union's Horizon 2020 research and innovation programme under grant Horizon 2020 research and innovation programme under grant agreement
agreement No. 644334 (NEAT). The views expressed are solely those of No. 644334 (NEAT). The views expressed are solely those of the
the author(s). author(s).
7. IANA Considerations 7. IANA Considerations
XX RFC ED - PLEASE REMOVE THIS SECTION XXX XX RFC ED - PLEASE REMOVE THIS SECTION XXX
This memo includes no request to IANA. This memo includes no request to IANA.
8. Security Considerations 8. Security Considerations
Authentication, confidentiality protection, and integrity protection Authentication, confidentiality protection, and integrity protection
are identified as Transport Features by [RFC8095]. As currently are identified as transport features [RFC8095]. As currently
deployed in the Internet, these features are generally provided by a deployed in the Internet, these transport features are generally
protocol or layer on top of the transport protocol; no current full- provided by a protocol or layer on top of the transport protocol; no
featured standards-track transport protocol provides these features current full-featured standards-track transport protocol provides
on its own. Therefore, these features are not considered in this these transport features on its own. Therefore, these transport
document, with the exception of native authentication capabilities of features are not considered in this document, with the exception of
TCP and SCTP for which the security considerations in [RFC5925] and native authentication capabilities of TCP and SCTP for which the
[RFC4895] apply. security considerations in [RFC5925] and [RFC4895] apply.
Security considerations for the use of UDP and UDP-Lite are provided
in the referenced RFCs. Security guidance for application usage is
provided in the UDP-Guidelines [RFC8085].
9. References 9. References
9.1. Normative References 9.1. Normative References
[FJ16] Fairhurst, G. and T. Jones, "Features of the User Datagram [FJ16] Fairhurst, G. and T. Jones, "Features of the User Datagram
Protocol (UDP) and Lightweight UDP (UDP-Lite) Transport Protocol (UDP) and Lightweight UDP (UDP-Lite) Transport
Protocols", draft-ietf-taps-transports-usage-udp-00 (work Protocols", Internet-draft draft-ietf-taps-transports-
in progress), November 2016. usage-udp-02, May 2017.
[I-D.ietf-tsvwg-sctp-ndata] [I-D.ietf-tsvwg-sctp-ndata]
Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann, Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann,
"Stream Schedulers and User Message Interleaving for the "Stream Schedulers and User Message Interleaving for the
Stream Control Transmission Protocol", Stream Control Transmission Protocol", draft-ietf-tsvwg-
draft-ietf-tsvwg-sctp-ndata-08 (work in progress), sctp-ndata-08 (work in progress), October 2016.
October 2016.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <http://www.rfc-editor.org/info/rfc793>.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, DOI 10.17487/ Communication Layers", STD 3, RFC 1122,
RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<http://www.rfc-editor.org/info/rfc1122>. <http://www.rfc-editor.org/info/rfc1122>.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP) Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, DOI 10.17487/ Partial Reliability Extension", RFC 3758,
RFC3758, May 2004, DOI 10.17487/RFC3758, May 2004,
<http://www.rfc-editor.org/info/rfc3758>. <http://www.rfc-editor.org/info/rfc3758>.
[RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla, [RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla,
"Authenticated Chunks for the Stream Control Transmission "Authenticated Chunks for the Stream Control Transmission
Protocol (SCTP)", RFC 4895, DOI 10.17487/RFC4895, Protocol (SCTP)", RFC 4895, DOI 10.17487/RFC4895, August
August 2007, <http://www.rfc-editor.org/info/rfc4895>. 2007, <http://www.rfc-editor.org/info/rfc4895>.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007, RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>. <http://www.rfc-editor.org/info/rfc4960>.
[RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M. [RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
Kozuka, "Stream Control Transmission Protocol (SCTP) Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061, DOI 10.17487/ Dynamic Address Reconfiguration", RFC 5061,
RFC5061, September 2007, DOI 10.17487/RFC5061, September 2007,
<http://www.rfc-editor.org/info/rfc5061>. <http://www.rfc-editor.org/info/rfc5061>.
[RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option", [RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option",
RFC 5482, DOI 10.17487/RFC5482, March 2009, RFC 5482, DOI 10.17487/RFC5482, March 2009,
<http://www.rfc-editor.org/info/rfc5482>. <http://www.rfc-editor.org/info/rfc5482>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925, Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <http://www.rfc-editor.org/info/rfc5925>. June 2010, <http://www.rfc-editor.org/info/rfc5925>.
[RFC6182] Ford, A., Raiciu, C., Handley, M., Barre, S., and J. [RFC6182] Ford, A., Raiciu, C., Handley, M., Barre, S., and J.
Iyengar, "Architectural Guidelines for Multipath TCP Iyengar, "Architectural Guidelines for Multipath TCP
Development", RFC 6182, DOI 10.17487/RFC6182, March 2011, Development", RFC 6182, DOI 10.17487/RFC6182, March 2011,
<http://www.rfc-editor.org/info/rfc6182>. <http://www.rfc-editor.org/info/rfc6182>.
[RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V.
Yasevich, "Sockets API Extensions for the Stream Control Yasevich, "Sockets API Extensions for the Stream Control
Transmission Protocol (SCTP)", RFC 6458, DOI 10.17487/ Transmission Protocol (SCTP)", RFC 6458,
RFC6458, December 2011, DOI 10.17487/RFC6458, December 2011,
<http://www.rfc-editor.org/info/rfc6458>. <http://www.rfc-editor.org/info/rfc6458>.
[RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control [RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control
Transmission Protocol (SCTP) Stream Reconfiguration", Transmission Protocol (SCTP) Stream Reconfiguration",
RFC 6525, DOI 10.17487/RFC6525, February 2012, RFC 6525, DOI 10.17487/RFC6525, February 2012,
<http://www.rfc-editor.org/info/rfc6525>. <http://www.rfc-editor.org/info/rfc6525>.
[RFC6817] Shalunov, S., Hazel, G., Iyengar, J., and M. Kuehlewind, [RFC6817] Shalunov, S., Hazel, G., Iyengar, J., and M. Kuehlewind,
"Low Extra Delay Background Transport (LEDBAT)", RFC 6817, "Low Extra Delay Background Transport (LEDBAT)", RFC 6817,
DOI 10.17487/RFC6817, December 2012, DOI 10.17487/RFC6817, December 2012,
skipping to change at page 44, line 37 skipping to change at page 53, line 26
"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<http://www.rfc-editor.org/info/rfc6824>. <http://www.rfc-editor.org/info/rfc6824>.
[RFC6897] Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application [RFC6897] Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application
Interface Considerations", RFC 6897, DOI 10.17487/RFC6897, Interface Considerations", RFC 6897, DOI 10.17487/RFC6897,
March 2013, <http://www.rfc-editor.org/info/rfc6897>. March 2013, <http://www.rfc-editor.org/info/rfc6897>.
[RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream [RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
Control Transmission Protocol (SCTP) Packets for End-Host Control Transmission Protocol (SCTP) Packets for End-Host
to End-Host Communication", RFC 6951, DOI 10.17487/ to End-Host Communication", RFC 6951,
RFC6951, May 2013, DOI 10.17487/RFC6951, May 2013,
<http://www.rfc-editor.org/info/rfc6951>. <http://www.rfc-editor.org/info/rfc6951>.
[RFC7053] Tuexen, M., Ruengeler, I., and R. Stewart, "SACK- [RFC7053] Tuexen, M., Ruengeler, I., and R. Stewart, "SACK-
IMMEDIATELY Extension for the Stream Control Transmission IMMEDIATELY Extension for the Stream Control Transmission
Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013, Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013,
<http://www.rfc-editor.org/info/rfc7053>. <http://www.rfc-editor.org/info/rfc7053>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<http://www.rfc-editor.org/info/rfc7413>. <http://www.rfc-editor.org/info/rfc7413>.
skipping to change at page 45, line 21 skipping to change at page 54, line 13
<http://www.rfc-editor.org/info/rfc7829>. <http://www.rfc-editor.org/info/rfc7829>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <http://www.rfc-editor.org/info/rfc8085>. March 2017, <http://www.rfc-editor.org/info/rfc8085>.
9.2. Informative References 9.2. Informative References
[I-D.draft-gjessing-taps-minset] [I-D.draft-gjessing-taps-minset]
Gjessing, S. and M. Welzl, "A Minimal Set of Transport Gjessing, S. and M. Welzl, "A Minimal Set of Transport
Services for TAPS Systems", draft-gjessing-taps-minset-04 Services for TAPS Systems", Internet-draft draft-gjessing-
(work in progress), March 2017. taps-minset-04, March 2017.
[RFC0854] Postel, J. and J. Reynolds, "Telnet Protocol [RFC0854] Postel, J. and J. Reynolds, "Telnet Protocol
Specification", STD 8, RFC 854, DOI 10.17487/RFC0854, Specification", STD 8, RFC 854, DOI 10.17487/RFC0854, May
May 1983, <http://www.rfc-editor.org/info/rfc854>. 1983, <http://www.rfc-editor.org/info/rfc854>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
of Explicit Congestion Notification (ECN) to IP", "Definition of the Differentiated Services Field (DS
RFC 3168, DOI 10.17487/RFC3168, September 2001, Field) in the IPv4 and IPv6 Headers", RFC 2474,
<http://www.rfc-editor.org/info/rfc3168>. DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<http://www.rfc-editor.org/info/rfc2475>.
[RFC3260] Grossman, D., "New Terminology and Clarifications for [RFC3260] Grossman, D., "New Terminology and Clarifications for
Diffserv", RFC 3260, DOI 10.17487/RFC3260, April 2002, Diffserv", RFC 3260, DOI 10.17487/RFC3260, April 2002,
<http://www.rfc-editor.org/info/rfc3260>. <http://www.rfc-editor.org/info/rfc3260>.
[RFC5461] Gont, F., "TCP's Reaction to Soft Errors", RFC 5461, [RFC5461] Gont, F., "TCP's Reaction to Soft Errors", RFC 5461,
DOI 10.17487/RFC5461, February 2009, DOI 10.17487/RFC5461, February 2009,
<http://www.rfc-editor.org/info/rfc5461>. <http://www.rfc-editor.org/info/rfc5461>.
[RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the [RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the
TCP Urgent Mechanism", RFC 6093, DOI 10.17487/RFC6093, TCP Urgent Mechanism", RFC 6093, DOI 10.17487/RFC6093,
January 2011, <http://www.rfc-editor.org/info/rfc6093>. January 2011, <http://www.rfc-editor.org/info/rfc6093>.
[RFC7414] Duke, M., Braden, R., Eddy, W., Blanton, E., and A. [RFC7414] Duke, M., Braden, R., Eddy, W., Blanton, E., and A.
Zimmermann, "A Roadmap for Transmission Control Protocol Zimmermann, "A Roadmap for Transmission Control Protocol
(TCP) Specification Documents", RFC 7414, DOI 10.17487/ (TCP) Specification Documents", RFC 7414,
RFC7414, February 2015, DOI 10.17487/RFC7414, February 2015,
<http://www.rfc-editor.org/info/rfc7414>. <http://www.rfc-editor.org/info/rfc7414>.
[RFC7657] Black, D., Ed. and P. Jones, "Differentiated Services [RFC7657] Black, D., Ed. and P. Jones, "Differentiated Services
(Diffserv) and Real-Time Communication", RFC 7657, (Diffserv) and Real-Time Communication", RFC 7657,
DOI 10.17487/RFC7657, November 2015, DOI 10.17487/RFC7657, November 2015,
<http://www.rfc-editor.org/info/rfc7657>. <http://www.rfc-editor.org/info/rfc7657>.
[RFC8095] Fairhurst, G., Ed., Trammell, B., Ed., and M. Kuehlewind, [RFC8095] Fairhurst, G., Ed., Trammell, B., Ed., and M. Kuehlewind,
Ed., "Services Provided by IETF Transport Protocols and Ed., "Services Provided by IETF Transport Protocols and
Congestion Control Mechanisms", RFC 8095, DOI 10.17487/ Congestion Control Mechanisms", RFC 8095,
RFC8095, March 2017, DOI 10.17487/RFC8095, March 2017,
<http://www.rfc-editor.org/info/rfc8095>. <http://www.rfc-editor.org/info/rfc8095>.
Appendix A. Overview of RFCs used as input for pass 1 Appendix A. Overview of RFCs used as input for pass 1
TCP: [RFC0793], [RFC1122], [RFC5482], [RFC5925], [RFC7413] TCP: [RFC0793], [RFC1122], [RFC5482], [RFC5925], [RFC7413]
MPTCP: [RFC6182], [RFC6824], [RFC6897] MPTCP: [RFC6182], [RFC6824], [RFC6897]
SCTP: RFCs without a socket API specification: [RFC3758], [RFC4895], SCTP: RFCs without a socket API specification: [RFC3758], [RFC4895],
[RFC4960], [RFC5061]. [RFC4960], [RFC5061].
RFCs that include a socket API specification: [RFC6458], RFCs that include a socket API specification: [RFC6458],
[RFC6525], [RFC6951], [RFC7053], [RFC7496] [RFC7829]. [RFC6525], [RFC6951], [RFC7053], [RFC7496] [RFC7829].
UDP(-Lite): See [FJ16] UDP(-Lite): See [FJ16]
LEDBAT: [RFC6817]. LEDBAT: [RFC6817].
Appendix B. How this document was developed Appendix B. How this document was developed
This section gives an overview of the method that was used to develop This section gives an overview of the method that was used to develop
this document. It was given to contributors for guidance, and it can this document. It was given to contributors for guidance, and it can
be helpful for future updates or extensions. be helpful for future updates or extensions.
This document is only concerned with Transport Features that are This document is only concerned with transport features that are
explicitly exposed to applications via primitives. It also strictly explicitly exposed to applications via primitives. It also strictly
follows RFC text: if a feature is truly relevant for an application, follows RFC text: if a transport feature is truly relevant for an
the RFCs should say so, and they should describe how to use and application, the RFCs should say so, and they should describe how to
configure it. Thus, the approach followed for developing this use and configure it. Thus, the approach followed for developing
document was to identify the right RFCs, then analyze and process this document was to identify the right RFCs, then analyze and
their text. process their text.
Primitives that MAY be implemented by a transport protocol were Primitives that MAY be implemented by a transport protocol were
excluded. To be included, the minimum requirement level for a excluded. To be included, the minimum requirement level for a
primitive to be implemented by a protocol was SHOULD. Where primitive to be implemented by a protocol was SHOULD. Where
[RFC2119]-style requirements levels are not used, primitives were [RFC2119]-style requirements levels are not used, primitives were
excluded when they are described in conjunction with statements like, excluded when they are described in conjunction with statements like,
e.g.: "some implementations also provide" or "an implementation may e.g.: "some implementations also provide" or "an implementation may
also". Excluded primitives or parameters were briefly described in a also". Excluded primitives or parameters were briefly described in a
dedicated subsection. dedicated subsection.
skipping to change at page 48, line 7 skipping to change at page 57, line 5
Parameters: Parameters:
Returns: Returns:
Comments: Comments:
The entries "Parameters", "Returns" and "Comments" were skipped when The entries "Parameters", "Returns" and "Comments" were skipped when
a primitive had no parameters, no described return value or no a primitive had no parameters, no described return value or no
comments seemed necessary, respectively. Optional parameters are comments seemed necessary, respectively. Optional parameters are
followed by "(optional)". When a default value is known, this was followed by "(optional)". When a default value is known, this was
also provided. also provided.
Pass 3: the main point of this pass is to identify transport protocol Pass 3: the main point of this pass is to identify transport features
features that are the result of static properties of protocols, for that are the result of static properties of protocols, for which all
which all protocols have to be listed together; this is then the protocols have to be listed together; this is then the final list of
final list of all available Transport Features. This list was all available transport features. This list was primarily based on
primarily based on text from pass 2, with additional input from pass text from pass 2, with additional input from pass 1 (but no external
1 (but no external sources). sources).
Appendix C. Revision information Appendix C. Revision information
XXX RFC-Ed please remove this section prior to publication. XXX RFC-Ed please remove this section prior to publication.
-00 (from draft-welzl-taps-transports): this now covers TCP based on -00 (from draft-welzl-taps-transports): this now covers TCP based on
all TCP RFCs (this means: if you know of something in any TCP RFC all TCP RFCs (this means: if you know of something in any TCP RFC
that you think should be addressed, please speak up!) as well as that you think should be addressed, please speak up!) as well as
SCTP, exclusively based on [RFC4960]. We decided to also incorporate SCTP, exclusively based on [RFC4960]. We decided to also incorporate
[RFC6458] for SCTP, but this hasn't happened yet. Terminology made [RFC6458] for SCTP, but this hasn't happened yet. Terminology made
skipping to change at page 48, line 39 skipping to change at page 57, line 37
-02: included UDP, UDP-Lite, and all extensions of SCTPs. This -02: included UDP, UDP-Lite, and all extensions of SCTPs. This
includes fixing the [RFC6458] omission from -00. includes fixing the [RFC6458] omission from -00.
-03: wrote security considerations. The "how to contribute" section -03: wrote security considerations. The "how to contribute" section
was updated to reflect how the document WAS created, not how it was updated to reflect how the document WAS created, not how it
SHOULD BE created; it also no longer wrongly says that Experimental SHOULD BE created; it also no longer wrongly says that Experimental
RFCs are excluded. Included LEDBAT. Changed abstract and intro to RFCs are excluded. Included LEDBAT. Changed abstract and intro to
reflect which protocols/mechanisms are covered (TCP, MPTCP, SCTP, reflect which protocols/mechanisms are covered (TCP, MPTCP, SCTP,
UDP, UDP-Lite, LEDBAT) instead of talking about "transport UDP, UDP-Lite, LEDBAT) instead of talking about "transport
protocols". Interleaving and stream scheduling added protocols". Interleaving and stream scheduling added (draft-ietf-
(draft-ietf-tsvwg-sctp-ndata). TFO added. "Set protocol parameters" tsvwg-sctp-ndata). TFO added. "Set protocol parameters" in SCTP
in SCTP replaced with per-parameter (or parameter group) primitives. replaced with per-parameter (or parameter group) primitives. More
More primitives added, mostly previously overlooked ones from primitives added, mostly previously overlooked ones from [RFC6458].
[RFC6458]. Updated terminology (s/transport service feature/ Updated terminology (s/transport service feature/transport feature)
transport feature) in line with an update of [RFC8095]. Made in line with an update of [RFC8095]. Made sequence of transport
sequence of transport features / primitives more logical. Combined features / primitives more logical. Combined MPTCP's add/rem subflow
MPTCP's add/rem subflow with SCTP's add/remove local address. with SCTP's add/remove local address.
-04: changed UDP's close into an ABORT (to better fit with the -04: changed UDP's close into an ABORT (to better fit with the
primitives of TCP and SCTP), and incorporated the corresponding primitives of TCP and SCTP), and incorporated the corresponding
transport feature in step 3 (this addresses a comment from Gorry transport feature in step 3 (this addresses a comment from Gorry
Fairhurst). Added TCP Authentication (RFC 5925, section 7.1). Fairhurst). Added TCP Authentication (RFC 5925, section 7.1).
Changed TFO from looking like a primitive in pass 1 to be a part of Changed TFO from looking like a primitive in pass 1 to be a part of
'open'. Changed description of SCTP authentication in pass 3 to 'open'. Changed description of SCTP authentication in pass 3 to
encompass both TCP and SCTP. Added citations of [RFC8095] and minset encompass both TCP and SCTP. Added citations of [RFC8095] and minset
[I-D.draft-gjessing-taps-minset] to the intro, to give the context of [I-D.draft-gjessing-taps-minset] to the intro, to give the context of
this document. this document.
-05: minor fix to TCP authentication (comment from Joe Touch),
several fixes from Gorry Fairhurst and Tom Jones. Language fixes;
updated to align with latest taps-transport-usage-udp ID.
Authors' Addresses Authors' Addresses
Michael Welzl Michael Welzl
University of Oslo University of Oslo
PO Box 1080 Blindern PO Box 1080 Blindern
Oslo, N-0316 Oslo N-0316
Norway Norway
Email: michawe@ifi.uio.no Email: michawe@ifi.uio.no
Michael Tuexen Michael Tuexen
Muenster University of Applied Sciences Muenster University of Applied Sciences
Stegerwaldstrasse 39 Stegerwaldstrasse 39
Steinfurt 48565 Steinfurt 48565
Germany Germany
Email: tuexen@fh-muenster.de Email: tuexen@fh-muenster.de
Naeem Khademi Naeem Khademi
University of Oslo University of Oslo
PO Box 1080 Blindern PO Box 1080 Blindern
Oslo, N-0316 Oslo N-0316
Norway Norway
Email: naeemk@ifi.uio.no Email: naeemk@ifi.uio.no
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