draft-ietf-taps-interface-11.txt   draft-ietf-taps-interface-12.txt 
TAPS Working Group B. Trammell, Ed. TAPS Working Group B. Trammell, Ed.
Internet-Draft Google Switzerland GmbH Internet-Draft Google Switzerland GmbH
Intended status: Standards Track M. Welzl, Ed. Intended status: Standards Track M. Welzl, Ed.
Expires: August 26, 2021 University of Oslo Expires: 11 October 2021 University of Oslo
T. Enghardt T. Enghardt
Netflix Netflix
G. Fairhurst G. Fairhurst
University of Aberdeen University of Aberdeen
M. Kuehlewind M. Kuehlewind
Ericsson Ericsson
C. Perkins C. Perkins
University of Glasgow University of Glasgow
P. Tiesel P. Tiesel
TU Berlin SAP SE
C. Wood C.A. Wood
Cloudflare Cloudflare
T. Pauly T. Pauly
Apple Inc. Apple Inc.
K. Rose K. Rose
Akamai Technologies, Inc. Akamai Technologies, Inc.
February 22, 2021 9 April 2021
An Abstract Application Layer Interface to Transport Services An Abstract Application Layer Interface to Transport Services
draft-ietf-taps-interface-11 draft-ietf-taps-interface-12
Abstract Abstract
This document describes an abstract application programming This document describes an abstract application programming
interface, API, to the transport layer, following the Transport interface, API, to the transport layer, following the Transport
Services Architecture. It supports the asynchronous, atomic Services Architecture. It supports the asynchronous, atomic
transmission of messages over transport protocols and network paths transmission of messages over transport protocols and network paths
dynamically selected at runtime. It is intended to replace the dynamically selected at runtime. It is intended to replace the
traditional BSD sockets API as the common interface to the transport traditional BSD sockets API as the common interface to the transport
layer, in an environment where endpoints could select from multiple layer, in an environment where endpoints could select from multiple
skipping to change at page 2, line 10 skipping to change at page 2, line 10
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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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 August 26, 2021. This Internet-Draft will expire on 11 October 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology and Notation . . . . . . . . . . . . . . . . 5 1.1. Terminology and Notation . . . . . . . . . . . . . . . . 5
1.2. Specification of Requirements . . . . . . . . . . . . . . 6 1.2. Specification of Requirements . . . . . . . . . . . . . . 6
2. Overview of Interface Design . . . . . . . . . . . . . . . . 6 2. Overview of Interface Design . . . . . . . . . . . . . . . . 7
3. API Summary . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. API Summary . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Usage Examples . . . . . . . . . . . . . . . . . . . . . 8 3.1. Usage Examples . . . . . . . . . . . . . . . . . . . . . 8
3.1.1. Server Example . . . . . . . . . . . . . . . . . . . 9 3.1.1. Server Example . . . . . . . . . . . . . . . . . . . 9
3.1.2. Client Example . . . . . . . . . . . . . . . . . . . 10 3.1.2. Client Example . . . . . . . . . . . . . . . . . . . 10
3.1.3. Peer Example . . . . . . . . . . . . . . . . . . . . 11 3.1.3. Peer Example . . . . . . . . . . . . . . . . . . . . 11
3.2. Transport Properties . . . . . . . . . . . . . . . . . . 12 3.2. Transport Properties . . . . . . . . . . . . . . . . . . 12
3.2.1. Transport Property Names . . . . . . . . . . . . . . 12 3.2.1. Transport Property Names . . . . . . . . . . . . . . 12
3.2.2. Transport Property Types . . . . . . . . . . . . . . 13 3.2.2. Transport Property Types . . . . . . . . . . . . . . 13
3.3. Scope of the Interface Definition . . . . . . . . . . . . 14 3.3. Scope of the Interface Definition . . . . . . . . . . . . 14
4. Pre-Establishment Phase . . . . . . . . . . . . . . . . . . . 15 4. Pre-Establishment Phase . . . . . . . . . . . . . . . . . . . 15
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4.1.1. Using Multicast Endpoints . . . . . . . . . . . . . . 17 4.1.1. Using Multicast Endpoints . . . . . . . . . . . . . . 17
4.1.2. Endpoint Aliases . . . . . . . . . . . . . . . . . . 17 4.1.2. Endpoint Aliases . . . . . . . . . . . . . . . . . . 17
4.1.3. Endpoint Examples . . . . . . . . . . . . . . . . . . 18 4.1.3. Endpoint Examples . . . . . . . . . . . . . . . . . . 18
4.2. Specifying Transport Properties . . . . . . . . . . . . . 19 4.2. Specifying Transport Properties . . . . . . . . . . . . . 19
4.2.1. Reliable Data Transfer (Connection) . . . . . . . . . 22 4.2.1. Reliable Data Transfer (Connection) . . . . . . . . . 22
4.2.2. Preservation of Message Boundaries . . . . . . . . . 22 4.2.2. Preservation of Message Boundaries . . . . . . . . . 22
4.2.3. Configure Per-Message Reliability . . . . . . . . . . 22 4.2.3. Configure Per-Message Reliability . . . . . . . . . . 22
4.2.4. Preservation of Data Ordering . . . . . . . . . . . . 22 4.2.4. Preservation of Data Ordering . . . . . . . . . . . . 22
4.2.5. Use 0-RTT Session Establishment with a Safely 4.2.5. Use 0-RTT Session Establishment with a Safely
Replayable Message . . . . . . . . . . . . . . . . . 23 Replayable Message . . . . . . . . . . . . . . . . . 23
4.2.6. Multistream Connections in Group . . . . . . . . . . 23 4.2.6. Multistream Connections in Group . . . . . . . . . . 23
4.2.7. Full Checksum Coverage on Sending . . . . . . . . . . 23 4.2.7. Full Checksum Coverage on Sending . . . . . . . . . . 23
4.2.8. Full Checksum Coverage on Receiving . . . . . . . . . 23 4.2.8. Full Checksum Coverage on Receiving . . . . . . . . . 23
4.2.9. Congestion control . . . . . . . . . . . . . . . . . 24 4.2.9. Congestion control . . . . . . . . . . . . . . . . . 24
4.2.10. Keep alive . . . . . . . . . . . . . . . . . . . . . 24 4.2.10. Keep alive . . . . . . . . . . . . . . . . . . . . . 24
4.2.11. Interface Instance or Type . . . . . . . . . . . . . 24 4.2.11. Interface Instance or Type . . . . . . . . . . . . . 24
4.2.12. Provisioning Domain Instance or Type . . . . . . . . 25 4.2.12. Provisioning Domain Instance or Type . . . . . . . . 25
4.2.13. Use Temporary Local Address . . . . . . . . . . . . . 26 4.2.13. Use Temporary Local Address . . . . . . . . . . . . . 26
4.2.14. Multi-Paths Transport . . . . . . . . . . . . . . . . 27 4.2.14. Multipath Transport . . . . . . . . . . . . . . . . . 27
4.2.15. Advertisement of Alternative Addresses . . . . . . . 28 4.2.15. Advertisement of Alternative Addresses . . . . . . . 28
4.2.16. Direction of communication . . . . . . . . . . . . . 28 4.2.16. Direction of communication . . . . . . . . . . . . . 28
4.2.17. Notification of ICMP soft error message arrival . . . 29 4.2.17. Notification of ICMP soft error message arrival . . . 29
4.2.18. Initiating side is not the first to write . . . . . . 29 4.2.18. Initiating side is not the first to write . . . . . . 29
4.3. Specifying Security Parameters and Callbacks . . . . . . 29 4.3. Specifying Security Parameters and Callbacks . . . . . . 29
4.3.1. Pre-Connection Parameters . . . . . . . . . . . . . . 30 4.3.1. Pre-Connection Parameters . . . . . . . . . . . . . . 30
4.3.2. Connection Establishment Callbacks . . . . . . . . . 31 4.3.2. Connection Establishment Callbacks . . . . . . . . . 31
5. Establishing Connections . . . . . . . . . . . . . . . . . . 31 5. Establishing Connections . . . . . . . . . . . . . . . . . . 31
5.1. Active Open: Initiate . . . . . . . . . . . . . . . . . . 31 5.1. Active Open: Initiate . . . . . . . . . . . . . . . . . . 31
5.2. Passive Open: Listen . . . . . . . . . . . . . . . . . . 33 5.2. Passive Open: Listen . . . . . . . . . . . . . . . . . . 33
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5.4. Connection Groups . . . . . . . . . . . . . . . . . . . . 36 5.4. Connection Groups . . . . . . . . . . . . . . . . . . . . 36
6. Managing Connections . . . . . . . . . . . . . . . . . . . . 37 6. Managing Connections . . . . . . . . . . . . . . . . . . . . 37
6.1. Generic Connection Properties . . . . . . . . . . . . . . 39 6.1. Generic Connection Properties . . . . . . . . . . . . . . 39
6.1.1. Required Minimum Corruption Protection Coverage for 6.1.1. Required Minimum Corruption Protection Coverage for
Receiving . . . . . . . . . . . . . . . . . . . . . . 39 Receiving . . . . . . . . . . . . . . . . . . . . . . 39
6.1.2. Connection Priority . . . . . . . . . . . . . . . . . 39 6.1.2. Connection Priority . . . . . . . . . . . . . . . . . 39
6.1.3. Timeout for Aborting Connection . . . . . . . . . . . 40 6.1.3. Timeout for Aborting Connection . . . . . . . . . . . 40
6.1.4. Timeout for keep alive packets . . . . . . . . . . . 40 6.1.4. Timeout for keep alive packets . . . . . . . . . . . 40
6.1.5. Connection Group Transmission Scheduler . . . . . . . 40 6.1.5. Connection Group Transmission Scheduler . . . . . . . 40
6.1.6. Capacity Profile . . . . . . . . . . . . . . . . . . 41 6.1.6. Capacity Profile . . . . . . . . . . . . . . . . . . 41
6.1.7. Policy for using Multi-Path Transports . . . . . . . 42 6.1.7. Policy for using Multipath Transports . . . . . . . . 42
6.1.8. Bounds on Send or Receive Rate . . . . . . . . . . . 43 6.1.8. Bounds on Send or Receive Rate . . . . . . . . . . . 43
6.1.9. Group Connection Limit . . . . . . . . . . . . . . . 43 6.1.9. Group Connection Limit . . . . . . . . . . . . . . . 43
6.1.10. Isolate Session . . . . . . . . . . . . . . . . . . . 44 6.1.10. Isolate Session . . . . . . . . . . . . . . . . . . . 44
6.1.11. Read-only Connection Properties . . . . . . . . . . . 44 6.1.11. Read-only Connection Properties . . . . . . . . . . . 44
6.2. TCP-specific Properties: User Timeout Option (UTO) . . . 45 6.2. TCP-specific Properties: User Timeout Option (UTO) . . . 45
6.2.1. Advertised User Timeout . . . . . . . . . . . . . . . 46 6.2.1. Advertised User Timeout . . . . . . . . . . . . . . . 46
6.2.2. User Timeout Enabled . . . . . . . . . . . . . . . . 46 6.2.2. User Timeout Enabled . . . . . . . . . . . . . . . . 46
6.2.3. Timeout Changeable . . . . . . . . . . . . . . . . . 46 6.2.3. Timeout Changeable . . . . . . . . . . . . . . . . . 46
6.3. Connection Lifecycle Events . . . . . . . . . . . . . . . 46 6.3. Connection Lifecycle Events . . . . . . . . . . . . . . . 46
6.3.1. Soft Errors . . . . . . . . . . . . . . . . . . . . . 47 6.3.1. Soft Errors . . . . . . . . . . . . . . . . . . . . . 47
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7.2.6. Priority in TAPS . . . . . . . . . . . . . . . . . . 59 7.2.6. Priority in TAPS . . . . . . . . . . . . . . . . . . 59
7.3. Receiving Data . . . . . . . . . . . . . . . . . . . . . 60 7.3. Receiving Data . . . . . . . . . . . . . . . . . . . . . 60
7.3.1. Enqueuing Receives . . . . . . . . . . . . . . . . . 60 7.3.1. Enqueuing Receives . . . . . . . . . . . . . . . . . 60
7.3.2. Receive Events . . . . . . . . . . . . . . . . . . . 61 7.3.2. Receive Events . . . . . . . . . . . . . . . . . . . 61
7.3.3. Receive Message Properties . . . . . . . . . . . . . 63 7.3.3. Receive Message Properties . . . . . . . . . . . . . 63
8. Connection Termination . . . . . . . . . . . . . . . . . . . 64 8. Connection Termination . . . . . . . . . . . . . . . . . . . 64
9. Connection State and Ordering of Operations and Events . . . 65 9. Connection State and Ordering of Operations and Events . . . 65
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 66 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 66
11. Privacy and Security Considerations . . . . . . . . . . . . . 66 11. Privacy and Security Considerations . . . . . . . . . . . . . 66
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 68 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 68
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 69 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 68
13.1. Normative References . . . . . . . . . . . . . . . . . . 69 13.1. Normative References . . . . . . . . . . . . . . . . . . 69
13.2. Informative References . . . . . . . . . . . . . . . . . 70 13.2. Informative References . . . . . . . . . . . . . . . . . 69
Appendix A. Implementation Mapping . . . . . . . . . . . . . . . 72 Appendix A. Implementation Mapping . . . . . . . . . . . . . . . 73
A.1. Types . . . . . . . . . . . . . . . . . . . . . . . . . . 73 A.1. Types . . . . . . . . . . . . . . . . . . . . . . . . . . 73
A.2. Events and Errors . . . . . . . . . . . . . . . . . . . . 73 A.2. Events and Errors . . . . . . . . . . . . . . . . . . . . 73
A.3. Time Duration . . . . . . . . . . . . . . . . . . . . . . 73 A.3. Time Duration . . . . . . . . . . . . . . . . . . . . . . 73
Appendix B. Convenience Functions . . . . . . . . . . . . . . . 73 Appendix B. Convenience Functions . . . . . . . . . . . . . . . 74
B.1. Adding Preference Properties . . . . . . . . . . . . . . 74 B.1. Adding Preference Properties . . . . . . . . . . . . . . 74
B.2. Transport Property Profiles . . . . . . . . . . . . . . . 74 B.2. Transport Property Profiles . . . . . . . . . . . . . . . 74
B.2.1. reliable-inorder-stream . . . . . . . . . . . . . . . 74 B.2.1. reliable-inorder-stream . . . . . . . . . . . . . . . 74
B.2.2. reliable-message . . . . . . . . . . . . . . . . . . 74 B.2.2. reliable-message . . . . . . . . . . . . . . . . . . 75
B.2.3. unreliable-datagram . . . . . . . . . . . . . . . . . 75 B.2.3. unreliable-datagram . . . . . . . . . . . . . . . . . 75
Appendix C. Relationship to the Minimal Set of Transport Appendix C. Relationship to the Minimal Set of Transport Services
Services for End Systems . . . . . . . . . . . . . . 75 for End Systems . . . . . . . . . . . . . . . . . . . . . 76
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 79
1. Introduction 1. Introduction
This document specifies a modern abstract application programming This document specifies a modern abstract application programming
interface (API) atop the high-level architecture for transport interface (API) atop the high-level architecture for transport
services defined in [I-D.ietf-taps-arch]. It supports the services defined in [I-D.ietf-taps-arch]. It supports the
asynchronous, atomic transmission of messages over transport asynchronous, atomic transmission of messages over transport
protocols and network paths dynamically selected at runtime. It is protocols and network paths dynamically selected at runtime. It is
intended to replace the traditional BSD sockets API as the common intended to replace the traditional BSD sockets API as the common
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1.1. Terminology and Notation 1.1. Terminology and Notation
This API is described in terms of Objects with which an application This API is described in terms of Objects with which an application
can interact; Actions the application can perform on these Objects; can interact; Actions the application can perform on these Objects;
Events, which an Object can send to an application asynchronously; Events, which an Object can send to an application asynchronously;
and Parameters associated with these Actions and Events. and Parameters associated with these Actions and Events.
The following notations, which can be combined, are used in this The following notations, which can be combined, are used in this
document: document:
o An Action creates an Object: * An Action creates an Object:
Object := Action() Object := Action()
o An Action creates an array of Objects: * An Action creates an array of Objects:
[]Object := Action() []Object := Action()
o An Action is performed on an Object: * An Action is performed on an Object:
Object.Action() Object.Action()
o An Object sends an Event: * An Object sends an Event:
Object -> Event<> Object -> Event<>
o An Action takes a set of Parameters; an Event contains a set of * An Action takes a set of Parameters; an Event contains a set of
Parameters. Action and Event parameters whose names are suffixed Parameters. Action and Event parameters whose names are suffixed
with a question mark are optional. with a question mark are optional.
Action(param0, param1?, ...) / Event<param0, param1, ...> Action(param0, param1?, ...) / Event<param0, param1, ...>
Actions associated with no Object are Actions on the abstract Actions associated with no Object are Actions on the abstract
interface itself; they are equivalent to Actions on a per-application interface itself; they are equivalent to Actions on a per-application
global context. global context.
We also make use of the following basic types: We also make use of the following basic types:
o Boolean: Instances take the value "true" or "false". * Boolean: Instances take the value "true" or "false".
o Integer: Instances take positive or negative numeric integer * Integer: Instances take positive or negative numeric integer
values, or sometimes special non-numeric (symbolic) values. values, or sometimes special non-numeric (symbolic) values.
o Numeric: Instances take positive or negative numeric values, or * Numeric: Instances take positive or negative numeric values, or
sometimes special non-numeric (symbolic) values. sometimes special non-numeric (symbolic) values.
o Enumeration: A family of types in which each instance takes one of * Enumeration: A family of types in which each instance takes one of
a fixed, predefined set of values specific to a given enumerated a fixed, predefined set of values specific to a given enumerated
type. type.
o Tuple: An ordered grouping of multiple value types, represented as * Tuple: An ordered grouping of multiple value types, represented as
a comma-separated list in parentheses, e.g., "(Enumeration, a comma-separated list in parentheses, e.g., "(Enumeration,
Preference)". Instances take a sequence of values each valid for Preference)". Instances take a sequence of values each valid for
the corresponding value type. The composition of types and their the corresponding value type. The composition of types and their
order depends on the property and is fixed for the property. order depends on the property and is fixed for the property.
o Array: Denoted []Type, an instance takes a value for each of zero * Array: Denoted []Type, an instance takes a value for each of zero
or more elements in a sequence of the given Type. An array may be or more elements in a sequence of the given Type. An array may be
of fixed or variable length. of fixed or variable length.
o Collection: An unordered grouping of one or more values of the * Collection: An unordered grouping of one or more values of the
same type. same type.
For guidance on how these abstract concepts may be implemented in For guidance on how these abstract concepts may be implemented in
languages in accordance with native design patterns and language and languages in accordance with native design patterns and language and
platform features, see Appendix A. platform features, see Appendix A.
1.2. Specification of Requirements 1.2. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
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14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Overview of Interface Design 2. Overview of Interface Design
The design of the interface specified in this document is based on a The design of the interface specified in this document is based on a
set of principles, themselves an elaboration on the architectural set of principles, themselves an elaboration on the architectural
design principles defined in [I-D.ietf-taps-arch]. The interface design principles defined in [I-D.ietf-taps-arch]. The interface
defined in this document provides: defined in this document provides:
o Access to a variety of transport protocols, independent of the the * Access to a variety of transport protocols, independent of the the
Protocol Stacks that will be used at runtime, such that all common Protocol Stacks that will be used at runtime, such that all common
features of these protocol stacks are made available to the features of these protocol stacks are made available to the
application in a transport-independent way to the degree possible, application in a transport-independent way to the degree possible,
enabling applications written to a single API to make use of enabling applications written to a single API to make use of
transport protocols in terms of the features they provide; transport protocols in terms of the features they provide;
o Message-orientation, as opposed to stream-orientation, using * Message-orientation, as opposed to stream-orientation, using
application-assisted framing and deframing where the underlying application-assisted framing and deframing where the underlying
transport does not provide these; transport does not provide these;
o Asynchronous Connection establishment, transmission, and * Asynchronous Connection establishment, transmission, and
reception, allowing concurrent operations during establishment and reception, allowing concurrent operations during establishment and
supporting event-driven application interactions with the supporting event-driven application interactions with the
transport layer, in line with developments in modern platforms and transport layer, in line with developments in modern platforms and
programming languages; programming languages;
o Explicit support for transport-specific features to be applied * Explicit support for transport-specific features to be applied
should that particular transport be part of a chosen Protocol should that particular transport be part of a chosen Protocol
Stack. Stack.
o Explicit support for security properties as first-order transport * Explicit support for security properties as first-order transport
features, and for configuration of cryptographic identities and features, and for configuration of cryptographic identities and
transport security parameters persistent across multiple transport security parameters persistent across multiple
Connections; and Connections; and
o Explicit support for multistreaming and multipath transport * Explicit support for multistreaming and multipath transport
protocols, and the grouping of related Connections into Connection protocols, and the grouping of related Connections into Connection
Groups through cloning of Connections, to allow applications to Groups through cloning of Connections, to allow applications to
take full advantage of new transport protocols supporting these take full advantage of new transport protocols supporting these
features. features.
3. API Summary 3. API Summary
The Transport Services API is the basic common abstract application The Transport Services API is the basic common abstract application
programming interface to the Transport Services Architecture defined programming interface to the Transport Services Architecture defined
in the TAPS Architecture [I-D.ietf-taps-arch]. in the TAPS Architecture [I-D.ietf-taps-arch].
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Preconnections and Connections. A Preconnection represents a set of Preconnections and Connections. A Preconnection represents a set of
properties and constraints on the selection and configuration of properties and constraints on the selection and configuration of
paths and protocols to establish a Connection with a Remote Endpoint. paths and protocols to establish a Connection with a Remote Endpoint.
A Connection represents a transport Protocol Stack on which data can A Connection represents a transport Protocol Stack on which data can
be sent to and/or received from a Remote Endpoint (i.e., depending on be sent to and/or received from a Remote Endpoint (i.e., depending on
the kind of transport, connections can be bi-directional or the kind of transport, connections can be bi-directional or
unidirectional). Connections can be created from Preconnections in unidirectional). Connections can be created from Preconnections in
three ways: by initiating the Preconnection (i.e., actively opening, three ways: by initiating the Preconnection (i.e., actively opening,
as in a client), through listening on the Preconnection (i.e., as in a client), through listening on the Preconnection (i.e.,
passively opening, as in a server), or rendezvousing on the passively opening, as in a server), or rendezvousing on the
Preconnection (i.e. peer to peer establishment). Preconnection (i.e. peer to peer establishment).
Once a Connection is established, data can be sent and received on it Once a Connection is established, data can be sent and received on it
in the form of Messages. The interface supports the preservation of in the form of Messages. The interface supports the preservation of
message boundaries both via explicit Protocol Stack support, and via message boundaries both via explicit Protocol Stack support, and via
application support through a Message Framer which finds message application support through a Message Framer which finds message
boundaries in a stream. Messages are received asynchronously through boundaries in a stream. Messages are received asynchronously through
event handlers registered by the application. Errors and other event handlers registered by the application. Errors and other
notifications also happen asynchronously on the Connection. It is notifications also happen asynchronously on the Connection. It is
not necessary for an application to handle all Events; some Events not necessary for an application to handle all Events; some Events
may have implementation-specific default handlers. The application may have implementation-specific default handlers. The application
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describe the details of application interaction with Objects through describe the details of application interaction with Objects through
Actions and Events in each phase of a Connection, following the Actions and Events in each phase of a Connection, following the
phases (Pre-Establishment, Establishment, Data Transfer, and phases (Pre-Establishment, Establishment, Data Transfer, and
Termination) described in Section 4.1 of [I-D.ietf-taps-arch]. Termination) described in Section 4.1 of [I-D.ietf-taps-arch].
3.1. Usage Examples 3.1. Usage Examples
The following usage examples illustrate how an application might use The following usage examples illustrate how an application might use
a Transport Services Interface to: a Transport Services Interface to:
o Act as a server, by listening for incoming connections, receiving * Act as a server, by listening for incoming connections, receiving
requests, and sending responses, see Section 3.1.1. requests, and sending responses, see Section 3.1.1.
o Act as a client, by connecting to a Remote Endpoint using * Act as a client, by connecting to a Remote Endpoint using
Initiate, sending requests, and receiving responses, see Initiate, sending requests, and receiving responses, see
Section 3.1.2. Section 3.1.2.
o Act as a peer, by connecting to a Remote Endpoint using Rendezvous * Act as a peer, by connecting to a Remote Endpoint using Rendezvous
while simultaneously waiting for incoming Connections, sending while simultaneously waiting for incoming Connections, sending
Messages, and receiving Messages, see Section 3.1.3. Messages, and receiving Messages, see Section 3.1.3.
The examples in this section presume that a transport protocol is The examples in this section presume that a transport protocol is
available between the Local and Remote Endpoints that provides available between the Local and Remote Endpoints that provides
Reliable Data Transfer, Preservation of data ordering, and Reliable Data Transfer, Preservation of data ordering, and
Preservation of Message Boundaries. In this case, the application Preservation of Message Boundaries. In this case, the application
can choose to receive only complete messages. can choose to receive only complete messages.
If none of the available transport protocols provides Preservation of If none of the available transport protocols provides Preservation of
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// Close the Connection in a Receive event handler // Close the Connection in a Receive event handler
Connection.Close() Connection.Close()
3.2. Transport Properties 3.2. Transport Properties
Each application using the Transport Services Interface declares its Each application using the Transport Services Interface declares its
preferences for how the transport service should operate using preferences for how the transport service should operate using
properties at each stage of the lifetime of a connection using properties at each stage of the lifetime of a connection using
Transport Properties, as defined in [I-D.ietf-taps-arch]. Transport Properties, as defined in [I-D.ietf-taps-arch].
Transport Properties are divided into Selection, Connection, and Transport Properties are divided into Selection, Connection, and
Message Properties. Selection Properties (see Section 4.2) can only Message Properties. Selection Properties (see The behavior of the
be set during pre-establishment. They are only used to specify which selected protocol stack(s) when sending Messages is controlled by
paths and protocol stacks can be used and are preferred by the Message Properties (see Section 4.2) can only be set during pre-
application. Although Connection Properties (see Section 6.1) can be establishment. They are only used to specify which paths and
set during pre-establishment, they may be changed later. They are protocol stacks can be used and are preferred by the application.
used to inform decisions made during establishment and to fine-tune Although Connection Properties (see Section 6.1) can be set during
the established connection. pre-establishment, they may be changed later. They are used to
The behavior of the selected protocol stack(s) when sending Messages inform decisions made during establishment and to fine-tune the
is controlled by Message Properties (see Section 7.1.3). established connection.Section 7.1.3).
All Transport Properties, regardless of the phase in which they are All Transport Properties, regardless of the phase in which they are
used, are organized within a single namespace. This enables setting used, are organized within a single namespace. This enables setting
them as defaults at earlier stages and querying them in later stages: them as defaults at earlier stages and querying them in later stages:
o Connection Properties can be set on Preconnections and Connections * Connection Properties can be set on Preconnections and Connections
o Message Properties can be set on Preconnections, Connections and * Message Properties can be set on Preconnections, Connections and
Messages Messages
o The effect of Selection Properties can be queried on Connections * The effect of Selection Properties can be queried on Connections
and Messages and Messages
Note that configuring Connection Properties and Message Properties on Note that configuring Connection Properties and Message Properties on
Preconnections is preferred over setting them later. Early Preconnections is preferred over setting them later. Early
specification of Connection Properties allows their use as additional specification of Connection Properties allows their use as additional
input to the selection process. Protocol Specific Properties, which input to the selection process. Protocol Specific Properties, which
enable configuration of specialized features of a specific protocol, enable configuration of specialized features of a specific protocol,
see Section 3.2 of [I-D.ietf-taps-arch], are not used as an input to see Section 3.2 of [I-D.ietf-taps-arch], are not used as an input to
the selection process but only support configuration if the the selection process but only support configuration if the
respective protocol has been selected. respective protocol has been selected.
3.2.1. Transport Property Names 3.2.1. Transport Property Names
Transport Properties are referred to by property names. For the Transport Properties are referred to by property names. For the
purposes of this document, these names are alphanumeric strings in purposes of this document, these names are alphanumeric strings in
which words may be separated by hyphens. These names serve two which words may be separated by hyphens. These names serve two
purposes: purposes:
o Allowing different components of a TAPS implementation to pass * Allowing different components of a TAPS implementation to pass
Transport Properties, e.g., between a language frontend and a Transport Properties, e.g., between a language frontend and a
policy manager, or as a representation of properties retrieved policy manager, or as a representation of properties retrieved
from a file or other storage. from a file or other storage.
o Making the code of different TAPS implementations look similar. * Making the code of different TAPS implementations look similar.
While individual programming languages may preclude strict While individual programming languages may preclude strict
adherence to the aforementioned naming convention (for instance, adherence to the aforementioned naming convention (for instance,
by prohibiting the use of hyphens in symbols), users interacting by prohibiting the use of hyphens in symbols), users interacting
with multiple implementations will still benefit from the with multiple implementations will still benefit from the
consistency resulting from the use of visually similar symbols. consistency resulting from the use of visually similar symbols.
Transport Property Names are hierarchically organized in the form Transport Property Names are hierarchically organized in the form
[<Namespace>.]<PropertyName>. [<Namespace>.]<PropertyName>.
o The Namespace component MUST be empty for well-known, generic * The Namespace component MUST be empty for well-known, generic
properties, i.e., for properties that are not specific to a properties, i.e., for properties that are not specific to a
protocol and are defined in an RFC. protocol and are defined in an RFC.
o Protocol Specific Properties MUST use the protocol acronym as the * Protocol Specific Properties MUST use the protocol acronym as the
Namespace, e.g., "tcp" for TCP specific Transport Properties. For Namespace, e.g., "tcp" for TCP specific Transport Properties. For
IETF protocols, property names under these namespaces SHOULD be IETF protocols, property names under these namespaces SHOULD be
defined in an RFC. defined in an RFC.
o Vendor or implementation specific properties MUST use a string * Vendor or implementation specific properties MUST use a string
identifying the vendor or implementation as the Namespace. identifying the vendor or implementation as the Namespace.
Namespaces for each of the keywords provided in the IANA protocol Namespaces for each of the keywords provided in the IANA protocol
numbers registry (see https://www.iana.org/assignments/protocol- numbers registry (see https://www.iana.org/assignments/protocol-
numbers/protocol-numbers.xhtml), reformatted where necessary to numbers/protocol-numbers.xhtml), reformatted where necessary to
conform to an implementation's naming conventions, are reserved for conform to an implementation's naming conventions, are reserved for
Protocol Specific Properties and MUST NOT be used for vendor or Protocol Specific Properties and MUST NOT be used for vendor or
implementation-specific properties. implementation-specific properties.
3.2.2. Transport Property Types 3.2.2. Transport Property Types
Transport Properties each have a type, which can be: Transport Properties each have a type, which can be:
o One of the basic types described in Section 1.1; or * One of the basic types described in Section 1.1; or
o Preference, which is an Enumeration with five possible values: * Preference, which is an Enumeration with five possible values:
Prohibit, Avoid, Ignore, Prefer, or Require. Each of these Prohibit, Avoid, Ignore, Prefer, or Require. Each of these
denotes a level of preference of a given property during protocol denotes a level of preference of a given property during protocol
selection. (See Section 4.2.) The Preference type is used only selection. (See Section 4.2.) The Preference type is used only
on Preconnections, and only for Selection Properties. on Preconnections, and only for Selection Properties.
3.3. Scope of the Interface Definition 3.3. Scope of the Interface Definition
This document defines a language- and platform-independent interface This document defines a language- and platform-independent interface
to a Transport Services system. Given the wide variety of languages to a Transport Services system. Given the wide variety of languages
and language conventions used to write applications that use the and language conventions used to write applications that use the
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There is no interoperability benefit in tightly defining how the There is no interoperability benefit in tightly defining how the
interface is presented to application programmers across diverse interface is presented to application programmers across diverse
platforms. However, maintaining the "shape" of the abstract platforms. However, maintaining the "shape" of the abstract
interface across different platforms reduces the effort for interface across different platforms reduces the effort for
programmers who learn the transport services interface to then apply programmers who learn the transport services interface to then apply
their knowledge to another platform. their knowledge to another platform.
We therefore make the following recommendations: We therefore make the following recommendations:
o Actions, Events, and Errors in implementations of this interface * Actions, Events, and Errors in implementations of this interface
SHOULD use the names given for them in the document, subject to SHOULD use the names given for them in the document, subject to
capitalization, punctuation, and other typographic conventions in capitalization, punctuation, and other typographic conventions in
the language of the implementation, unless the implementation the language of the implementation, unless the implementation
itself uses different names for substantially equivalent objects itself uses different names for substantially equivalent objects
for networking by convention. for networking by convention.
o Implementations of this interface SHOULD implement each Selection * Implementations of this interface SHOULD implement each Selection
Property, Connection Property, and Message Context Property Property, Connection Property, and Message Context Property
specified in this document. Each interface SHOULD be implemented specified in this document. Each interface SHOULD be implemented
even when in a specific implementation/platform it will always even when in a specific implementation/platform it will always
result in no operation, e.g. there is no action when the API result in no operation, e.g. there is no action when the API
specifies a Property that is not available in a transport protocol specifies a Property that is not available in a transport protocol
implemented on a specific platform. For example, if TCP is the implemented on a specific platform. For example, if TCP is the
only underlying transport protocol, the Message Property only underlying transport protocol, the Message Property
"msgOrdered" can be implemented (trivially, as a no-op) as "msgOrdered" can be implemented (trivially, as a no-op) as
disabling the requirement for ordering will not have any effect on disabling the requirement for ordering will not have any effect on
delivery order for Connections over TCP. Similarly, the "msg- delivery order for Connections over TCP. Similarly, the "msg-
lifetime" Message Property can be implemented but ignored, as the lifetime" Message Property can be implemented but ignored, as the
description of this Property states that "it is not guaranteed description of this Property states that "it is not guaranteed
that a Message will not be sent when its Lifetime has expired". that a Message will not be sent when its Lifetime has expired".
o Implementations may use other representations for Transport * Implementations may use other representations for Transport
Property Names, e.g., by providing constants, but should provide a Property Names, e.g., by providing constants, but should provide a
straight-forward mapping between their representation and the straight-forward mapping between their representation and the
property names specified here. property names specified here.
4. Pre-Establishment Phase 4. Pre-Establishment Phase
The Pre-Establishment phase allows applications to specify properties The Pre-Establishment phase allows applications to specify properties
for the Connections that they are about to make, or to query the API for the Connections that they are about to make, or to query the API
about potential Connections they could make. about potential Connections they could make.
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state that describes the properties of a Connection that might exist state that describes the properties of a Connection that might exist
in the future. This state comprises Local Endpoint and Remote in the future. This state comprises Local Endpoint and Remote
Endpoint Objects that denote the endpoints of the potential Endpoint Objects that denote the endpoints of the potential
Connection (see Section 4.1), the Selection Properties (see Connection (see Section 4.1), the Selection Properties (see
Section 4.2), any preconfigured Connection Properties (Section 6.1), Section 4.2), any preconfigured Connection Properties (Section 6.1),
and the security parameters (see Section 4.3): and the security parameters (see Section 4.3):
Preconnection := NewPreconnection([]LocalEndpoint, Preconnection := NewPreconnection([]LocalEndpoint,
[]RemoteEndpoint, []RemoteEndpoint,
TransportProperties, TransportProperties,
SecurityParameters) SecurityParameters?)
At least one Local Endpoint MUST be specified if the Preconnection is At least one Local Endpoint MUST be specified if the Preconnection is
used to Listen() for incoming Connections, but the list of Local used to Listen() for incoming Connections, but the list of Local
Endpoints MAY be empty if the Preconnection is used to Initiate() Endpoints MAY be empty if the Preconnection is used to Initiate()
connections. If no Local Endpoint is specified, the Transport connections. If no Local Endpoint is specified, the Transport
Services system will assign an ephemeral local port to the Connection Services system will assign an ephemeral local port to the Connection
on the appropriate interface(s). At least one Remote Endpoint MUST on the appropriate interface(s). At least one Remote Endpoint MUST
be specified if the Preconnection is used to Initiate() Connections, be specified if the Preconnection is used to Initiate() Connections,
but the list of Remote Endpoints MAY be empty if the Preconnection is but the list of Remote Endpoints MAY be empty if the Preconnection is
used to Listen() for incoming Connections. At least one Local used to Listen() for incoming Connections. At least one Local
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LocalSpecifier := NewLocalEndpoint() LocalSpecifier := NewLocalEndpoint()
A single Endpoint Object represents the identity of a network host. A single Endpoint Object represents the identity of a network host.
That endpoint can be more or less specific depending on which That endpoint can be more or less specific depending on which
identifiers are set. For example, an Endpoint that only specifies a identifiers are set. For example, an Endpoint that only specifies a
hostname may in fact end up corresponding to several different IP hostname may in fact end up corresponding to several different IP
addresses on different hosts. addresses on different hosts.
An Endpoint Object can be configured with the following identifiers: An Endpoint Object can be configured with the following identifiers:
o Hostname (string) * Hostname (string)
RemoteSpecifier.WithHostname("example.com") RemoteSpecifier.WithHostname("example.com")
o Port (a 16-bit integer) or a Service (string) that maps to a port * Port (a 16-bit integer) or a Service (string) that maps to a port
RemoteSpecifier.WithPort(443) RemoteSpecifier.WithPort(443)
RemoteSpecifier.WithService("https") RemoteSpecifier.WithService("https")
o IP address (IPv4 or IPv6 address) * IP address (IPv4 or IPv6 address)
RemoteSpecifier.WithIPv4Address(192.0.2.21) RemoteSpecifier.WithIPv4Address(192.0.2.21)
RemoteSpecifier.WithIPv6Address(2001:db8:4920:e29d:a420:7461:7073:0a) RemoteSpecifier.WithIPv6Address(2001:db8:4920:e29d:a420:7461:7073:0a)
o Interface (string name) * Interface (string name)
LocalSpecifier.WithInterface("en0") LocalSpecifier.WithInterface("en0")
An Endpoint cannot have multiple identifiers of a same type set. An Endpoint cannot have multiple identifiers of a same type set.
That is, an endpoint cannot have two IP addresses specified. Two That is, an endpoint cannot have two IP addresses specified. Two
separate IP addresses are represented as two Endpoint Objects. If a separate IP addresses are represented as two Endpoint Objects. If a
Preconnection specifies a Remote Endpoint with a specific IP address Preconnection specifies a Remote Endpoint with a specific IP address
set, it will only establish Connections to that IP address. If, on set, it will only establish Connections to that IP address. If, on
the other hand, the Remote Endpoint specifies a hostname but no the other hand, the Remote Endpoint specifies a hostname but no
addresses, the Connection can perform name resolution and attempt addresses, the Connection can perform name resolution and attempt
using any address derived from the original hostname of the Remote using any address derived from the original hostname of the Remote
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Since there could be paths over which some transport protocols are Since there could be paths over which some transport protocols are
unable to operate, or remote endpoints that support only specific unable to operate, or remote endpoints that support only specific
network addresses or transports, transport protocol selection is network addresses or transports, transport protocol selection is
necessarily tied to path selection. This may involve choosing necessarily tied to path selection. This may involve choosing
between multiple local interfaces that are connected to different between multiple local interfaces that are connected to different
access networks. access networks.
Most Selection Properties are represented as Preferences, which can Most Selection Properties are represented as Preferences, which can
take one of five values: take one of five values:
+------------+------------------------------------------------------+ +============+========================================+
| Preference | Effect | | Preference | Effect |
+------------+------------------------------------------------------+ +============+========================================+
| Require | Select only protocols/paths providing the property, | | Require | Select only protocols/paths providing |
| | fail otherwise | | | the property, fail otherwise |
| | | +------------+----------------------------------------+
| Prefer | Prefer protocols/paths providing the property, | | Prefer | Prefer protocols/paths providing the |
| | proceed otherwise | | | property, proceed otherwise |
| | | +------------+----------------------------------------+
| Ignore | No preference | | Ignore | No preference |
| | | +------------+----------------------------------------+
| Avoid | Prefer protocols/paths not providing the property, | | Avoid | Prefer protocols/paths not providing |
| | proceed otherwise | | | the property, proceed otherwise |
| | | +------------+----------------------------------------+
| Prohibit | Select only protocols/paths not providing the | | Prohibit | Select only protocols/paths not |
| | property, fail otherwise | | | providing the property, fail otherwise |
+------------+------------------------------------------------------+ +------------+----------------------------------------+
Table 1: Selection Property Preference Levels Table 1: Selection Property Preference Levels
The implementation MUST ensure an outcome that is consistent with all The implementation MUST ensure an outcome that is consistent with all
application requirements expressed using Require and Prohibit. While application requirements expressed using Require and Prohibit. While
preferences expressed using Prefer and Avoid influence protocol and preferences expressed using Prefer and Avoid influence protocol and
path selection as well, outcomes can vary given the same Selection path selection as well, outcomes can vary given the same Selection
Properties, because the available protocols and paths can differ Properties, because the available protocols and paths can differ
across systems and contexts. However, implementations are across systems and contexts. However, implementations are
RECOMMENDED to seek to provide a consistent outcome to an RECOMMENDED to seek to provide a consistent outcome to an
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prevent linking connections over time when a stable address, prevent linking connections over time when a stable address,
sometimes called "permanent" address, is not needed. There are some sometimes called "permanent" address, is not needed. There are some
caveats to note when specifying this property. First, if an caveats to note when specifying this property. First, if an
application Requires the use of temporary addresses, the resulting application Requires the use of temporary addresses, the resulting
Connection cannot use IPv4, because temporary addresses do not exist Connection cannot use IPv4, because temporary addresses do not exist
in IPv4. Second, temporary local addresses might involve trading off in IPv4. Second, temporary local addresses might involve trading off
privacy for performance. For instance, temporary addresses can privacy for performance. For instance, temporary addresses can
interfere with resumption mechanisms that some protocols rely on to interfere with resumption mechanisms that some protocols rely on to
reduce initial latency. reduce initial latency.
4.2.14. Multi-Paths Transport 4.2.14. Multipath Transport
Name: multipath Name: multipath
Type: Enumeration Type: Enumeration
Default: Disabled for connections created through initiate and Default: Disabled for connections created through initiate and
rendezvous, Passive for listeners rendezvous, Passive for listeners
This property specifies whether and how applications want to take This property specifies whether and how applications want to take
advantage of transferring data across multiple paths between the same advantage of transferring data across multiple paths between the same
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values whenever possible. However, as discussed in [RFC8922], many values whenever possible. However, as discussed in [RFC8922], many
transport security protocols require specific security parameters and transport security protocols require specific security parameters and
constraints from the client at the time of configuration and actively constraints from the client at the time of configuration and actively
during a handshake. These configuration parameters need to be during a handshake. These configuration parameters need to be
specified in the pre-connection phase and are created as follows: specified in the pre-connection phase and are created as follows:
SecurityParameters := NewSecurityParameters() SecurityParameters := NewSecurityParameters()
Security configuration parameters and sample usage follow: Security configuration parameters and sample usage follow:
o Local identity and private keys: Used to perform private key * Local identity and private keys: Used to perform private key
operations and prove one's identity to the Remote Endpoint. operations and prove one's identity to the Remote Endpoint.
(Note, if private keys are not available, e.g., since they are (Note, if private keys are not available, e.g., since they are
stored in hardware security modules (HSMs), handshake callbacks stored in hardware security modules (HSMs), handshake callbacks
must be used. See below for details.) must be used. See below for details.)
SecurityParameters.Set(identity, myIdentity) SecurityParameters.Set(identity, myIdentity)
SecurityParameters.Set(key-pair, myPrivateKey, myPublicKey) SecurityParameters.Set(key-pair, myPrivateKey, myPublicKey)
o Supported algorithms: Used to restrict what parameters are used by * Supported algorithms: Used to restrict what parameters are used by
underlying transport security protocols. When not specified, underlying transport security protocols. When not specified,
these algorithms should use known and safe defaults for the these algorithms should use known and safe defaults for the
system. Parameters include: ciphersuites, supported groups, and system. Parameters include: ciphersuites, supported groups, and
signature algorithms. These parameters take a collection of signature algorithms. These parameters take a collection of
supported algorithms as parameter. supported algorithms as parameter.
SecurityParameters.Set(supported-group, "secp256k1") SecurityParameters.Set(supported-group, "secp256k1")
SecurityParameters.Set(ciphersuite, "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256") SecurityParameters.Set(ciphersuite, "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256")
SecurityParameters.Set(signature-algorithm, "ed25519") SecurityParameters.Set(signature-algorithm, "ed25519")
o Pre-Shared Key import: Used to install pre-shared keying material * Pre-Shared Key import: Used to install pre-shared keying material
established out-of-band. Each pre-shared keying material is established out-of-band. Each pre-shared keying material is
associated with some identity that typically identifies its use or associated with some identity that typically identifies its use or
has some protocol-specific meaning to the Remote Endpoint. has some protocol-specific meaning to the Remote Endpoint.
SecurityParameters.Set(pre-shared-key, key, identity) SecurityParameters.Set(pre-shared-key, key, identity)
o Session cache management: Used to tune session cache capacity, * Session cache management: Used to tune session cache capacity,
lifetime, and other policies. lifetime, and other policies.
SecurityParameters.Set(max-cached-sessions, 16) SecurityParameters.Set(max-cached-sessions, 16)
SecurityParameters.Set(cached-session-lifetime-seconds, 3600) SecurityParameters.Set(cached-session-lifetime-seconds, 3600)
Representation of Security Parameters in implementations should Representation of Security Parameters in implementations should
parallel that chosen for Transport Property names as recommended in parallel that chosen for Transport Property names as recommended in
Section 3.3. Section 3.3.
4.3.2. Connection Establishment Callbacks 4.3.2. Connection Establishment Callbacks
Security decisions, especially pertaining to trust, are not static. Security decisions, especially pertaining to trust, are not static.
Once configured, parameters may also be supplied during connection Once configured, parameters may also be supplied during connection
establishment. These are best handled as client-provided callbacks. establishment. These are best handled as client-provided callbacks.
Security handshake callbacks that may be invoked during connection Security handshake callbacks that may be invoked during connection
establishment include: establishment include:
o Trust verification callback: Invoked when a Remote Endpoint's * Trust verification callback: Invoked when a Remote Endpoint's
trust must be validated before the handshake protocol can trust must be validated before the handshake protocol can
continue. continue.
TrustCallback := NewCallback({ TrustCallback := NewCallback({
// Handle trust, return the result // Handle trust, return the result
}) })
SecurityParameters.SetTrustVerificationCallback(trustCallback) SecurityParameters.SetTrustVerificationCallback(trustCallback)
o Identity challenge callback: Invoked when a private key operation * Identity challenge callback: Invoked when a private key operation
is required, e.g., when local authentication is requested by a is required, e.g., when local authentication is requested by a
remote. remote.
ChallengeCallback := NewCallback({ ChallengeCallback := NewCallback({
// Handle challenge // Handle challenge
}) })
SecurityParameters.SetIdentityChallengeCallback(challengeCallback) SecurityParameters.SetIdentityChallengeCallback(challengeCallback)
5. Establishing Connections 5. Establishing Connections
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Entangled Connections can be created using the Clone Action: Entangled Connections can be created using the Clone Action:
Connection := Connection.Clone() Connection := Connection.Clone()
Calling Clone on a Connection yields a group of Connections: the Calling Clone on a Connection yields a group of Connections: the
parent Connection on which Clone was called, and a resulting cloned parent Connection on which Clone was called, and a resulting cloned
Connection. The connections within a group are "entangled" with each Connection. The connections within a group are "entangled" with each
other, and become part of a Connection Group. Calling Clone on any other, and become part of a Connection Group. Calling Clone on any
of these Connections adds another Connection to the Connection Group, of these Connections adds another Connection to the Connection Group,
and so on. "Entangled" Connections share all Connection Properties and so on. "Entangled" Connections share all Connection Properties
except "Connection Priority" (see Section 6.1.2) . Like all other except "Connection Priority" (see Section 6.1.2) . Like all other
Properties, Connection Priority is copied to the new Connection when Properties, Connection Priority is copied to the new Connection when
calling Clone(), but it is not entangled: Changing Connection calling Clone(), but it is not entangled: Changing Connection
Priority on one Connection does not change it on the other Priority on one Connection does not change it on the other
Connections in the same Connection Group. Connections in the same Connection Group.
The stack of Message Framers associated with a Connection are also The stack of Message Framers associated with a Connection are also
copied to the cloned Connection when calling Clone. In other words, copied to the cloned Connection when calling Clone. In other words,
a cloned Connection has the same stack of Message Framers as the a cloned Connection has the same stack of Message Framers as the
Connection from which they are Cloned, but these Framers may Connection from which they are Cloned, but these Framers may
internally maintain per-Connection state. internally maintain per-Connection state.
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At any point, the application can query Connection Properties. At any point, the application can query Connection Properties.
ConnectionProperties := Connection.GetProperties() ConnectionProperties := Connection.GetProperties()
value := ConnectionProperties.Get(property) value := ConnectionProperties.Get(property)
if ConnectionProperties.Has(boolean_or_preference_property) then ... if ConnectionProperties.Has(boolean_or_preference_property) then ...
Depending on the status of the connection, the queried Connection Depending on the status of the connection, the queried Connection
Properties will include different information: Properties will include different information:
o The connection state, which can be one of the following: * The connection state, which can be one of the following:
Establishing, Established, Closing, or Closed. Establishing, Established, Closing, or Closed.
o Whether the connection can be used to send data. A connection can * Whether the connection can be used to send data. A connection can
not be used for sending if the connection was created with the not be used for sending if the connection was created with the
Selection Property "Direction of Communication" set to Selection Property "Direction of Communication" set to
"unidirectional receive" or if a Message marked as "Final" was "unidirectional receive" or if a Message marked as "Final" was
sent over this connection. See Section 7.1.3.5. sent over this connection. See Section 7.1.3.5.
o Whether the connection can be used to receive data. A connection * Whether the connection can be used to receive data. A connection
cannot be used for reading if the connection was created with the cannot be used for reading if the connection was created with the
Selection Property "Direction of Communication" set to Selection Property "Direction of Communication" set to
"unidirectional send" or if a Message marked as "Final" was "unidirectional send" or if a Message marked as "Final" was
received. See Section 7.3.3.3. The latter is only supported by received. See Section 7.3.3.3. The latter is only supported by
certain transport protocols, e.g., by TCP as half-closed certain transport protocols, e.g., by TCP as half-closed
connection. connection.
o For Connections that are Established or Closing: Transport * For Connections that are Established or Closing: Transport
Properties that the application specified on the Preconnection. Properties that the application specified on the Preconnection.
See Section 4.2. Selection properties of type "Preference" will See Section 4.2. Selection properties of type "Preference" will
be exposed as boolean values indicating whether or not the be exposed as boolean values indicating whether or not the
property applies to the selected transport. property applies to the selected transport.
o For Connections that are Established, Closing, or Closed: * For Connections that are Established, Closing, or Closed:
Selection (Section 4.2) and Connection Properties (Section 6.1) of Selection (Section 4.2) and Connection Properties (Section 6.1) of
the actual protocols that were selected and instantiated. the actual protocols that were selected and instantiated.
Selection Properties indicate whether or not the Connection has or Selection Properties indicate whether or not the Connection has or
offers a certain Selection Property. The actually instantiated offers a certain Selection Property. The actually instantiated
protocol stack might not match all Protocol Selection Properties protocol stack might not match all Protocol Selection Properties
that the application specified on the Preconnection. For example, that the application specified on the Preconnection. For example,
a certain Protocol Selection Property that an application a certain Protocol Selection Property that an application
specified as Preferred might not actually be present in the chosen specified as Preferred might not actually be present in the chosen
protocol stack because none of the currently available transport protocol stack because none of the currently available transport
protocols had this feature. protocols had this feature.
o For Connections that are Established, additional properties of the * For Connections that are Established, additional properties of the
path(s) in use. These properties can be derived from the local path(s) in use. These properties can be derived from the local
provisioning domain [RFC7556], measurements by the Protocol Stack, provisioning domain [RFC7556], measurements by the Protocol Stack,
or other sources. or other sources.
6.1. Generic Connection Properties 6.1. Generic Connection Properties
Generic Connection Properties are defined independent of the chosen Generic Connection Properties are defined independent of the chosen
protocol stack and therefore available on all Connections. protocol stack and therefore available on all Connections.
Many Connection Properties have a corresponding Selection Property Many Connection Properties have a corresponding Selection Property
skipping to change at page 42, line 42 skipping to change at page 42, line 42
relatively long period of time. Transport Services system relatively long period of time. Transport Services system
implementations that map the requested capacity profile onto per- implementations that map the requested capacity profile onto per-
connection DSCP signaling without multiplexing SHOULD assign a connection DSCP signaling without multiplexing SHOULD assign a
DSCP Assured Forwarding (AF11,AF12,AF13,AF14) [RFC2597] PHB per DSCP Assured Forwarding (AF11,AF12,AF13,AF14) [RFC2597] PHB per
Section 4.8 of [RFC4594]. Section 4.8 of [RFC4594].
The Capacity Profile for a selected protocol stack may be modified on The Capacity Profile for a selected protocol stack may be modified on
a per-Message basis using the Transmission Profile Message Property; a per-Message basis using the Transmission Profile Message Property;
see Section 7.1.3.8. see Section 7.1.3.8.
6.1.7. Policy for using Multi-Path Transports 6.1.7. Policy for using Multipath Transports
Name: multipath-policy Name: multipath-policy
Type: Enumeration Type: Enumeration
Default: Handover Default: Handover
This property specifies the local policy for transferring data across This property specifies the local policy for transferring data across
multiple paths between the same end hosts if Parallel Use of Multiple multiple paths between the same end hosts if Multipath Transport is
Paths is not set to Disabled (see Section 4.2.14). Possible values not set to Disabled (see Section 4.2.14). Possible values are:
are:
Handover: The connection ought only to attempt to migrate between Handover: The connection ought only to attempt to migrate between
different paths when the original path is lost or becomes different paths when the original path is lost or becomes
unusable. The thresholds used to declare a path unusable are unusable. The thresholds used to declare a path unusable are
implementation specific. implementation specific.
Interactive: The connection ought only to attempt to minimize the Interactive: The connection ought only to attempt to minimize the
latency for interactive traffic patterns by transmitting data latency for interactive traffic patterns by transmitting data
across multiple paths when this is beneficial. The goal of across multiple paths when this is beneficial. The goal of
minimizing the latency will be balanced against the cost of each minimizing the latency will be balanced against the cost of each
skipping to change at page 44, line 26 skipping to change at page 44, line 28
Type: Boolean Type: Boolean
Default: false Default: false
When set to true, this property will initiate new Connections using When set to true, this property will initiate new Connections using
as little cached information (such as session tickets or cookies) as as little cached information (such as session tickets or cookies) as
possible from previous connections that are not entangled with it. possible from previous connections that are not entangled with it.
Any state generated by this Connection will only be shared with Any state generated by this Connection will only be shared with
entangled connections. Cloned Connections will use saved state from entangled connections. Cloned Connections will use saved state from
within the Connection Group. within the Connection Group. This is used for separating Connection
Contexts as specified in [I-D.ietf-taps-arch].
Note that this does not guarantee no leakage of information, as Note that this does not guarantee no leakage of information, as
implementations may not be able to fully isolate all caches (e.g. implementations may not be able to fully isolate all caches (e.g.
RTT estimates). Note that this property may degrade connection RTT estimates). Note that this property may degrade connection
performance. performance.
6.1.11. Read-only Connection Properties 6.1.11. Read-only Connection Properties
The following generic Connection Properties are read-only, i.e. they The following generic Connection Properties are read-only, i.e. they
cannot be changed by an application. cannot be changed by an application.
skipping to change at page 55, line 38 skipping to change at page 55, line 38
This only takes effect when the transport uses a network layer that This only takes effect when the transport uses a network layer that
supports this functionality. When it does take effect, setting this supports this functionality. When it does take effect, setting this
property to true will cause the Don't Fragment bit to be set in the property to true will cause the Don't Fragment bit to be set in the
IP header, and attempts to send a message with this property set to a IP header, and attempts to send a message with this property set to a
size greater than the transport's current estimate of its maximum size greater than the transport's current estimate of its maximum
packet size ("singularTransmissionMsgMaxLen") will result in a packet size ("singularTransmissionMsgMaxLen") will result in a
"SendError". "SendError".
7.1.3.10. No Segmentation 7.1.3.10. No Segmentation
Name: noTransportFragmentation Name: noSegmentation
Type: Boolean Type: Boolean
Default: false Default: false
When set to true, this property requests the network layer at the When set to true, this property requests the network layer at the
sending endpoint to not fragment the packets generated by the sending endpoint to not fragment the packets generated by the
transport layer. When running over IPv4, setting this property to transport layer. When running over IPv4, setting this property to
true will also cause the Don't Fragment bit to be set in the IP true will also cause the Don't Fragment bit to be set in the IP
header. When this property is set, an attempt to send a message size header. When this property is set, an attempt to send a message size
skipping to change at page 62, line 31 skipping to change at page 62, line 31
ReceivedPartial may deliver them in a sequence like this: A1, B1, B2, ReceivedPartial may deliver them in a sequence like this: A1, B1, B2,
A2, A3, B3, because the messageContext allows the application to A2, A3, B3, because the messageContext allows the application to
identify the pieces as belonging to Message A and B, respectively. identify the pieces as belonging to Message A and B, respectively.
However, a sequence like: A1, A3 will never occur. However, a sequence like: A1, A3 will never occur.
If the minIncompleteLength in the Receive request was set to be If the minIncompleteLength in the Receive request was set to be
infinite (indicating a request to receive only complete Messages), infinite (indicating a request to receive only complete Messages),
the ReceivedPartial event may still be delivered if one of the the ReceivedPartial event may still be delivered if one of the
following conditions is true: following conditions is true:
o the underlying Protocol Stack supports message boundary * the underlying Protocol Stack supports message boundary
preservation, and the size of the Message is larger than the preservation, and the size of the Message is larger than the
buffers available for a single message; buffers available for a single message;
o the underlying Protocol Stack does not support message boundary * the underlying Protocol Stack does not support message boundary
preservation, and the Message Framer (see Section 7.1.2) cannot preservation, and the Message Framer (see Section 7.1.2) cannot
determine the end of the message using the buffer space it has determine the end of the message using the buffer space it has
available; or available; or
o the underlying Protocol Stack does not support message boundary * the underlying Protocol Stack does not support message boundary
preservation, and no Message Framer was supplied by the preservation, and no Message Framer was supplied by the
application application
Note that in the absence of message boundary preservation or a Note that in the absence of message boundary preservation or a
Message Framer, all bytes received on the Connection will be Message Framer, all bytes received on the Connection will be
represented as one large Message of indeterminate length. represented as one large Message of indeterminate length.
7.3.2.3. ReceiveError 7.3.2.3. ReceiveError
Connection -> ReceiveError<messageContext, reason?> Connection -> ReceiveError<messageContext, reason?>
skipping to change at page 64, line 40 skipping to change at page 64, line 40
Connection that is entangled with this one in a Connection Group. Connection that is entangled with this one in a Connection Group.
Connection.Close() Connection.Close()
The Closed Event informs the application that the Remote Endpoint has The Closed Event informs the application that the Remote Endpoint has
closed the Connection. There is no guarantee that a remote Close closed the Connection. There is no guarantee that a remote Close
will indeed be signaled. will indeed be signaled.
Connection -> Closed<> Connection -> Closed<>
Abort terminates a Connection without delivering any remaining data. Abort terminates a Connection without delivering any remaining
This action does not affect any other Connection that is entangled Messages. This action does not affect any other Connection that is
with this one in a Connection Group. entangled with this one in a Connection Group.
Connection.Abort() Connection.Abort()
AbortGroup terminates a Connection and also terminates any other CloseGroup gracefully terminates a Connection and any other
Connections that are entangled with this one in a Connection Group. Connections that are entangled with this one in a Connection Group.
For example, all of the Connections in a group might be streams of a For example, all of the Connections in a group might be streams of a
single session for a multistreaming protocol; aborting the entire single session for a multistreaming protocol; closing the entire
group would close the underlying session. See also Section 5.4. group will close the underlying session. See also Section 5.4. As
with Close, any Messages remaining to be processed on a Connection
will be handled prior to closing.
Connection.CloseGroup()
AbortGroup terminates a Connection and any other Connections that are
entangled with this one in a Connection Group without delivering any
remaining Messages.
Connection.AbortGroup() Connection.AbortGroup()
A ConnectionError informs the application that: 1) data could not be A ConnectionError informs the application that: 1) data could not be
delivered to the peer after a timeout, or 2) the Connection has been delivered to the peer after a timeout, or 2) the Connection has been
aborted (e.g., because the peer has called Abort). There is no aborted (e.g., because the peer has called Abort). There is no
guarantee that an Abort will indeed be signaled. guarantee that an Abort will indeed be signaled.
Connection -> ConnectionError<reason?> Connection -> ConnectionError<reason?>
9. Connection State and Ordering of Operations and Events 9. Connection State and Ordering of Operations and Events
This interface is designed to be independent of an implementation's This interface is designed to be independent of an implementation's
skipping to change at page 65, line 20 skipping to change at page 65, line 29
9. Connection State and Ordering of Operations and Events 9. Connection State and Ordering of Operations and Events
This interface is designed to be independent of an implementation's This interface is designed to be independent of an implementation's
concurrency model. The details of how exactly actions are handled, concurrency model. The details of how exactly actions are handled,
and how events are dispatched, are implementation dependent. and how events are dispatched, are implementation dependent.
Each transition of connection state is associated with one of more Each transition of connection state is associated with one of more
events: events:
o Ready<> occurs when a Connection created with Initiate() or * Ready<> occurs when a Connection created with Initiate() or
InitiateWithSend() transitions to Established state. InitiateWithSend() transitions to Established state.
o ConnectionReceived<> occurs when a Connection created with * ConnectionReceived<> occurs when a Connection created with
Listen() transitions to Established state. Listen() transitions to Established state.
o RendezvousDone<> occurs when a Connection created with * RendezvousDone<> occurs when a Connection created with
Rendezvous() transitions to Established state. Rendezvous() transitions to Established state.
o Closed<> occurs when a Connection transitions to Closed state * Closed<> occurs when a Connection transitions to Closed state
without error. without error.
o InitiateError<> occurs when a Connection created with Initiate() * InitiateError<> occurs when a Connection created with Initiate()
transitions from Establishing state to Closed state due to an transitions from Establishing state to Closed state due to an
error. error.
o ConnectionError<> occurs when a Connection transitions to Closed * ConnectionError<> occurs when a Connection transitions to Closed
state due to an error in all other circumstances. state due to an error in all other circumstances.
The following diagram shows the possible states of a Connection and The following diagram shows the possible states of a Connection and
the events that occur upon a transition from one state to another. the events that occur upon a transition from one state to another.
(*) (**) (*) (**)
Establishing -----> Established -----> Closed Establishing -----> Established -----> Closing ------> Closed
| ^ | ^
| | | |
+-----------------------------------+ +---------------------------------------------------+
InitiateError<> InitiateError<>
(*) Ready<>, ConnectionReceived<>, RendezvousDone<> (*) Ready<>, ConnectionReceived<>, RendezvousDone<>
(**) Closed<>, ConnectionError<> (**) Closed<>, ConnectionError<>
Figure 2: Connection State Diagram Figure 2: Connection State Diagram
The interface provides the following guarantees about the ordering of The interface provides the following guarantees about the ordering of
operations: operations:
o Sent<> events will occur on a Connection in the order in which the * Sent<> events will occur on a Connection in the order in which the
Messages were sent (i.e., delivered to the kernel or to the Messages were sent (i.e., delivered to the kernel or to the
network interface, depending on implementation). network interface, depending on implementation).
o Received<> will never occur on a Connection before it is * Received<> will never occur on a Connection before it is
Established; i.e. before a Ready<> event on that Connection, or a Established; i.e. before a Ready<> event on that Connection, or a
ConnectionReceived<> or RendezvousDone<> containing that ConnectionReceived<> or RendezvousDone<> containing that
Connection. Connection.
o No events will occur on a Connection after it is Closed; i.e., * No events will occur on a Connection after it is Closed; i.e.,
after a Closed<> event, an InitiateError<> or ConnectionError<> after a Closed<> event, an InitiateError<> or ConnectionError<>
will not occur on that connection. To ensure this ordering, will not occur on that connection. To ensure this ordering,
Closed<> will not occur on a Connection while other events on the Closed<> will not occur on a Connection while other events on the
Connection are still locally outstanding (i.e., known to the Connection are still locally outstanding (i.e., known to the
interface and waiting to be dealt with by the application). interface and waiting to be dealt with by the application).
10. IANA Considerations 10. IANA Considerations
RFC-EDITOR: Please remove this section before publication. RFC-EDITOR: Please remove this section before publication.
skipping to change at page 69, line 6 skipping to change at page 69, line 4
Thanks to Stuart Cheshire, Josh Graessley, David Schinazi, and Eric Thanks to Stuart Cheshire, Josh Graessley, David Schinazi, and Eric
Kinnear for their implementation and design efforts, including Happy Kinnear for their implementation and design efforts, including Happy
Eyeballs, that heavily influenced this work. Thanks to Laurent Chuat Eyeballs, that heavily influenced this work. Thanks to Laurent Chuat
and Jason Lee for initial work on the Post Sockets interface, from and Jason Lee for initial work on the Post Sockets interface, from
which this work has evolved. Thanks to Maximilian Franke for asking which this work has evolved. Thanks to Maximilian Franke for asking
good questions based on implementation experience and for good questions based on implementation experience and for
contributing text, e.g., on multicast. contributing text, e.g., on multicast.
13. References 13. References
13.1. Normative References 13.1. Normative References
[I-D.ietf-taps-arch] [I-D.ietf-taps-arch]
Pauly, T., Trammell, B., Brunstrom, A., Fairhurst, G., Pauly, T., Trammell, B., Brunstrom, A., Fairhurst, G.,
Perkins, C., Tiesel, P., and C. Wood, "An Architecture for Perkins, C., Tiesel, P., and C. Wood, "An Architecture for
Transport Services", draft-ietf-taps-arch-09 (work in Transport Services", Work in Progress, Internet-Draft,
progress), November 2020. draft-ietf-taps-arch-09, 2 November 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-taps-arch-
09.txt>.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, [RFC2914] Floyd, S., "Congestion Control Principles", BCP 41,
RFC 2914, DOI 10.17487/RFC2914, September 2000, RFC 2914, DOI 10.17487/RFC2914, September 2000,
<https://www.rfc-editor.org/info/rfc2914>. <https://www.rfc-editor.org/info/rfc2914>.
skipping to change at page 70, line 9 skipping to change at page 70, line 7
<https://www.rfc-editor.org/info/rfc8303>. <https://www.rfc-editor.org/info/rfc8303>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
13.2. Informative References 13.2. Informative References
[I-D.ietf-httpbis-priority] [I-D.ietf-httpbis-priority]
Oku, K. and L. Pardue, "Extensible Prioritization Scheme Oku, K. and L. Pardue, "Extensible Prioritization Scheme
for HTTP", draft-ietf-httpbis-priority-03 (work in for HTTP", Work in Progress, Internet-Draft, draft-ietf-
progress), January 2021. httpbis-priority-03, 11 January 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-httpbis-
priority-03.txt>.
[I-D.ietf-taps-impl] [I-D.ietf-taps-impl]
Brunstrom, A., Pauly, T., Enghardt, T., Grinnemo, K., Brunstrom, A., Pauly, T., Enghardt, T., Grinnemo, K.,
Jones, T., Tiesel, P., Perkins, C., and M. Welzl, Jones, T., Tiesel, P., Perkins, C., and M. Welzl,
"Implementing Interfaces to Transport Services", draft- "Implementing Interfaces to Transport Services", Work in
ietf-taps-impl-08 (work in progress), November 2020. Progress, Internet-Draft, draft-ietf-taps-impl-08, 2
November 2020, <http://www.ietf.org/internet-drafts/draft-
ietf-taps-impl-08.txt>.
[I-D.ietf-tsvwg-datagram-plpmtud] [I-D.ietf-tsvwg-datagram-plpmtud]
Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and
T. Voelker, "Packetization Layer Path MTU Discovery for T. Voelker, "Packetization Layer Path MTU Discovery for
Datagram Transports", draft-ietf-tsvwg-datagram-plpmtud-22 Datagram Transports", Work in Progress, Internet-Draft,
(work in progress), June 2020. draft-ietf-tsvwg-datagram-plpmtud-22, 10 June 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-
datagram-plpmtud-22.txt>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>. <https://www.rfc-editor.org/info/rfc2474>.
[RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski, [RFC2597] Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
"Assured Forwarding PHB Group", RFC 2597, "Assured Forwarding PHB Group", RFC 2597,
DOI 10.17487/RFC2597, June 1999, DOI 10.17487/RFC2597, June 1999,
<https://www.rfc-editor.org/info/rfc2597>. <https://www.rfc-editor.org/info/rfc2597>.
[RFC3246] Davie, B., Charny, A., Bennet, J., Benson, K., Le Boudec, [RFC3246] Davie, B., Charny, A., Bennet, J.C.R., Benson, K., Le
J., Courtney, W., Davari, S., Firoiu, V., and D. Boudec, J.Y., Courtney, W., Davari, S., Firoiu, V., and D.
Stiliadis, "An Expedited Forwarding PHB (Per-Hop Stiliadis, "An Expedited Forwarding PHB (Per-Hop
Behavior)", RFC 3246, DOI 10.17487/RFC3246, March 2002, Behavior)", RFC 3246, DOI 10.17487/RFC3246, March 2002,
<https://www.rfc-editor.org/info/rfc3246>. <https://www.rfc-editor.org/info/rfc3246>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<https://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
skipping to change at page 73, line 13 skipping to change at page 73, line 21
could be implemented via event queues, handler functions or classes, could be implemented via event queues, handler functions or classes,
communicating sequential processes, or other asynchronous calling communicating sequential processes, or other asynchronous calling
conventions. conventions.
A.1. Types A.1. Types
The basic types mentioned in Section 1.1 typically have natural The basic types mentioned in Section 1.1 typically have natural
correspondences in practical programming languages, perhaps correspondences in practical programming languages, perhaps
constrained by implementation-specific limitations. For example: constrained by implementation-specific limitations. For example:
o An Integer can typically be represented in C by an "int" or * An Integer can typically be represented in C by an "int" or
"long", subject to the underlying platform's ranges for each. To "long", subject to the underlying platform's ranges for each. To
accommodate special values, a C function that returns a non- accommodate special values, a C function that returns a non-
negative "int" on success may return -1 on failure. In Python, negative "int" on success may return -1 on failure. In Python,
such a function might return "None" or raise an exception. such a function might return "None" or raise an exception.
o In C, a Tuple may be represented as a "struct" with one member for * In C, a Tuple may be represented as a "struct" with one member for
each of the value types in the ordered grouping. In Python, by each of the value types in the ordered grouping. In Python, by
contrast, a Tuple may be represented natively as a "tuple", a contrast, a Tuple may be represented natively as a "tuple", a
sequence of dynamically-typed elements. sequence of dynamically-typed elements.
o A Collection may be represented as a "std::set" in C++ or as a * A Collection may be represented as a "std::set" in C++ or as a
"set" in Python. In C, it may be represented as an array or as a "set" in Python. In C, it may be represented as an array or as a
higher-level data structure with appropriate accessors defined. higher-level data structure with appropriate accessors defined.
A.2. Events and Errors A.2. Events and Errors
This specification treats Events and Errors similarly. Errors, just This specification treats Events and Errors similarly. Errors, just
as any other Events, may occur asynchronously in network as any other Events, may occur asynchronously in network
applications. However, implementations of this interface may report applications. However, implementations of this interface may report
Errors synchronously, according to the error handling idioms of the Errors synchronously, according to the error handling idioms of the
implementation platform, where they can be immediately detected, such implementation platform, where they can be immediately detected, such
skipping to change at page 74, line 32 skipping to change at page 74, line 35
Property objects (see Section 4.2) that are pre-configured with Property objects (see Section 4.2) that are pre-configured with
frequently used sets of properties. Implementations should at least frequently used sets of properties. Implementations should at least
offer short-hands to specify the following property profiles: offer short-hands to specify the following property profiles:
B.2.1. reliable-inorder-stream B.2.1. reliable-inorder-stream
This profile provides reliable, in-order transport service with This profile provides reliable, in-order transport service with
congestion control. TCP is an example of a protocol that provides congestion control. TCP is an example of a protocol that provides
this service. It should consist of the following properties: this service. It should consist of the following properties:
+-----------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+-----------------------+---------+ +=======================+=========+
| reliability | require | | reliability | require |
| | | +-----------------------+---------+
| preserveOrder | require | | preserveOrder | require |
| | | +-----------------------+---------+
| congestionControl | require | | congestionControl | require |
| | | +-----------------------+---------+
| preserveMsgBoundaries | ignore | | preserveMsgBoundaries | ignore |
+-----------------------+---------+ +-----------------------+---------+
Table 2
B.2.2. reliable-message B.2.2. reliable-message
This profile provides message-preserving, reliable, in-order This profile provides message-preserving, reliable, in-order
transport service with congestion control. SCTP is an example of a transport service with congestion control. SCTP is an example of a
protocol that provides this service. It should consist of the protocol that provides this service. It should consist of the
following properties: following properties:
+-----------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+-----------------------+---------+ +=======================+=========+
| reliability | require | | reliability | require |
| | | +-----------------------+---------+
| preserveOrder | require | | preserveOrder | require |
| | | +-----------------------+---------+
| congestionControl | require | | congestionControl | require |
| | | +-----------------------+---------+
| preserveMsgBoundaries | require | | preserveMsgBoundaries | require |
+-----------------------+---------+ +-----------------------+---------+
Table 3
B.2.3. unreliable-datagram B.2.3. unreliable-datagram
This profile provides unreliable datagram transport service. An This profile provides unreliable datagram transport service. An
example of a protocol that provides this service is UDP. It consists example of a protocol that provides this service is UDP. It consists
of the following properties: of the following properties:
+-----------------------+---------+ +=======================+=========+
| Property | Value | | Property | Value |
+-----------------------+---------+ +=======================+=========+
| reliability | ignore | | reliability | ignore |
| | | +-----------------------+---------+
| preserveOrder | ignore | | preserveOrder | ignore |
| | | +-----------------------+---------+
| congestionControl | ignore | | congestionControl | ignore |
| | | +-----------------------+---------+
| preserveMsgBoundaries | require | | preserveMsgBoundaries | require |
| | | +-----------------------+---------+
| safely replayable | true | | safely replayable | true |
+-----------------------+---------+ +-----------------------+---------+
Table 4
Applications that choose this Transport Property Profile for latency Applications that choose this Transport Property Profile for latency
reasons should also consider setting an appropriate Capacity Profile reasons should also consider setting an appropriate Capacity Profile
Property, see Section 6.1.6 and could benefit from controlling Property, see Section 6.1.6 and could benefit from controlling
checksum coverage, see Section 4.2.7 and Section 4.2.8. checksum coverage, see Section 4.2.7 and Section 4.2.8.
Appendix C. Relationship to the Minimal Set of Transport Services for Appendix C. Relationship to the Minimal Set of Transport Services for
End Systems End Systems
[RFC8923] identifies a minimal set of transport services that end [RFC8923] identifies a minimal set of transport services that end
systems should offer. These services make all non-security-related systems should offer. These services make all non-security-related
skipping to change at page 76, line 12 skipping to change at page 76, line 24
is reflected in the present API. For brevity, it is based on the is reflected in the present API. For brevity, it is based on the
list in Section 4.1 of [RFC8923], updated according to the discussion list in Section 4.1 of [RFC8923], updated according to the discussion
in Section 5 of [RFC8923]. The present API covers all elements of in Section 5 of [RFC8923]. The present API covers all elements of
this section except "Notification of Excessive Retransmissions (early this section except "Notification of Excessive Retransmissions (early
warning below abortion threshold)". This list is a subset of the warning below abortion threshold)". This list is a subset of the
transport features in Appendix A of [RFC8923], which refers to the transport features in Appendix A of [RFC8923], which refers to the
primitives in "pass 2" (Section 4) of [RFC8303] for further details primitives in "pass 2" (Section 4) of [RFC8303] for further details
on the implementation with TCP, MPTCP, UDP, UDP-Lite, SCTP and on the implementation with TCP, MPTCP, UDP, UDP-Lite, SCTP and
LEDBAT. LEDBAT.
o Connect: "Initiate" Action (Section 5.1). * Connect: "Initiate" Action (Section 5.1).
o Listen: "Listen" Action (Section 5.2). * Listen: "Listen" Action (Section 5.2).
o Specify number of attempts and/or timeout for the first * Specify number of attempts and/or timeout for the first
establishment message: "timeout" parameter of "Initiate" establishment message: "timeout" parameter of "Initiate"
(Section 5.1) or "InitiateWithSend" Action (Section 7.2.5). (Section 5.1) or "InitiateWithSend" Action (Section 7.2.5).
o Disable MPTCP: "Parallel Use of Multiple Paths" Property * Disable MPTCP: "Multipath Transport" Property (Section 4.2.14).
(Section 4.2.14).
o Hand over a message to reliably transfer (possibly multiple times) * Hand over a message to reliably transfer (possibly multiple times)
before connection establishment: "InitiateWithSend" Action before connection establishment: "InitiateWithSend" Action
(Section 7.2.5). (Section 7.2.5).
o Change timeout for aborting connection (using retransmit limit or * Change timeout for aborting connection (using retransmit limit or
time value): "Timeout for Aborting Connection" property, using a time value): "Timeout for Aborting Connection" property, using a
time value (Section 6.1.3). time value (Section 6.1.3).
o Timeout event when data could not be delivered for too long: * Timeout event when data could not be delivered for too long:
"ConnectionError" Event (Section 8). "ConnectionError" Event (Section 8).
o Suggest timeout to the peer: "TCP-specific Property: User Timeout" * Suggest timeout to the peer: "TCP-specific Properties: User
(Section 6.2). Timeout Option (UTO)" (Section 6.2).
o Notification of ICMP error message arrival: "Notification of ICMP * Notification of ICMP error message arrival: "Notification of ICMP
soft error message arrival" property (Section 4.2.17). soft error message arrival" property (Section 4.2.17).
o Choose a scheduler to operate between streams of an association: * Choose a scheduler to operate between streams of an association:
"Connection Group Transmission Scheduler" property "Connection Group Transmission Scheduler" property
(Section 6.1.5). (Section 6.1.5).
o Configure priority or weight for a scheduler: "Connection * Configure priority or weight for a scheduler: "Connection
Priority" property (Section 6.1.2). Priority" property (Section 6.1.2).
o "Specify checksum coverage used by the sender" and "Disable * "Specify checksum coverage used by the sender" and "Disable
checksum when sending": "Corruption Protection Length" property checksum when sending": "Sending Corruption Protection Length"
(Section 7.1.3.6) and "Full Checksum Coverage on Sending" property property (Section 7.1.3.6) and "Full Checksum Coverage on Sending"
(Section 4.2.7). property (Section 4.2.7).
o "Specify minimum checksum coverage required by receiver" and * "Specify minimum checksum coverage required by receiver" and
"Disable checksum requirement when receiving": "Required Minimum "Disable checksum requirement when receiving": "Required Minimum
Corruption Protection Coverage for Receiving" property Corruption Protection Coverage for Receiving" property
(Section 6.1.1) and "Full Checksum Coverage on Receiving" property (Section 6.1.1) and "Full Checksum Coverage on Receiving" property
(Section 4.2.8). (Section 4.2.8).
o "Specify DF field": "No Network-Layer Fragmentation" property * "Specify DF field": "No Network-Layer Fragmentation" property
(Section 7.1.3.9). (Section 7.1.3.9).
o "Request not to bundle messages": "No Transport-Layer * "Request not to bundle messages": "No Segmentation" property
Fragmentation" property (Section 7.1.3.10). (Section 7.1.3.10).
o Get max. transport-message size that may be sent using a non- * Get max. transport-message size that may be sent using a non-
fragmented IP packet from the configured interface: "Maximum fragmented IP packet from the configured interface: "Maximum
Message Size Before Fragmentation or Segmentation" property Message Size Before Fragmentation or Segmentation" property
(Section 6.1.11.2). (Section 6.1.11.2).
o Get max. transport-message size that may be received from the * Get max. transport-message size that may be received from the
configured interface: "Maximum Message Size on Receive" property configured interface: "Maximum Message Size on Receive" property
(Section 6.1.11.4). (Section 6.1.11.4).
o Obtain ECN field: "ECN" is a defined UDP(-Lite)-specific read-only * Obtain ECN field: "UDP(-Lite)-specific Property: ECN" is a read-
Message Property of the MessageContext object (Section 7.3.3.1). only Message Property of the MessageContext object
(Section 7.3.3.1).
o "Specify DSCP field", "Disable Nagle algorithm", "Enable and * "Specify DSCP field", "Disable Nagle algorithm", "Enable and
configure a "Low Extra Delay Background Transfer"": as suggested configure a "Low Extra Delay Background Transfer"": as suggested
in Section 5.5 of [RFC8923], these transport features are in Section 5.5 of [RFC8923], these transport features are
collectively offered via the "Capacity Profile" property collectively offered via the "Capacity Profile" property
(Section 6.1.6). Per-Message control is offered via the "Message (Section 6.1.6). Per-Message control is offered via the "Message
Capacity Profile Override" property (Section 7.1.3.8). Capacity Profile Override" property (Section 7.1.3.8).
o Close after reliably delivering all remaining data, causing an * Close after reliably delivering all remaining data, causing an
event informing the application on the other side: this is offered event informing the application on the other side: this is offered
by the "Close" Action with slightly changed semantics in line with by the "Close" Action with slightly changed semantics in line with
the discussion in Section 5.2 of [RFC8923] (Section 8). the discussion in Section 5.2 of [RFC8923] (Section 8).
o "Abort without delivering remaining data, causing an event * "Abort without delivering remaining data, causing an event
informing the application on the other side" and "Abort without informing the application on the other side" and "Abort without
delivering remaining data, not causing an event informing the delivering remaining data, not causing an event informing the
application on the other side": this is offered by the "Abort" application on the other side": this is offered by the "Abort"
action without promising that this is signaled to the other side. action without promising that this is signaled to the other side.
If it is, a "ConnectionError" Event will fire at the peer If it is, a "ConnectionError" Event will fire at the peer
(Section 8). (Section 8).
o "Reliably transfer data, with congestion control", "Reliably * "Reliably transfer data, with congestion control", "Reliably
transfer a message, with congestion control" and "Unreliably transfer a message, with congestion control" and "Unreliably
transfer a message": data is transferred via the "Send" action transfer a message": data is transferred via the "Send" action
(Section 7.2). Reliability is controlled via the "Reliable Data (Section 7.2). Reliability is controlled via the "Reliable Data
Transfer (Connection)" (Section 4.2.1) property and the "Reliable Transfer (Connection)" (Section 4.2.1) property and the "Reliable
Data Transfer (Message)" Message Property (Section 7.1.3.7). Data Transfer (Message)" Message Property (Section 7.1.3.7).
Transmitting data as a message or without delimiters is controlled Transmitting data as a message or without delimiters is controlled
via Message Framers (Section 7.1.2). The choice of congestion via Message Framers (Section 7.1.2). The choice of congestion
control is provided via the "Congestion control" property control is provided via the "Congestion control" property
(Section 4.2.9). (Section 4.2.9).
o Configurable Message Reliability: the "Lifetime" Message Property * Configurable Message Reliability: the "Lifetime" Message Property
implements a time-based way to configure message reliability implements a time-based way to configure message reliability
(Section 7.1.3.1). (Section 7.1.3.1).
o "Ordered message delivery (potentially slower than unordered)" and * "Ordered message delivery (potentially slower than unordered)" and
"Unordered message delivery (potentially faster than ordered)": "Unordered message delivery (potentially faster than ordered)":
these two transport features are controlled via the Message these two transport features are controlled via the Message
Property "Ordered" (Section 7.1.3.3). Property "Ordered" (Section 7.1.3.3).
o Request not to delay the acknowledgement (SACK) of a message: * Request not to delay the acknowledgement (SACK) of a message:
should the protocol support it, this is one of the transport should the protocol support it, this is one of the transport
features the Transport Services system can apply when an features the Transport Services system can apply when an
application uses the "Capacity Profile" Property (Section 6.1.6) application uses the "Capacity Profile" Property (Section 6.1.6)
or the "Message Capacity Profile Override" Message Property or the "Message Capacity Profile Override" Message Property
(Section 7.1.3.8) with value "Low Latency/Interactive". (Section 7.1.3.8) with value "Low Latency/Interactive".
o Receive data (with no message delimiting): "Received" Event * Receive data (with no message delimiting): "Received" Event
(Section 7.3.2.1). See Section 7.1.2 for handling Message framing (Section 7.3.2.1). See Section 7.1.2 for handling Message framing
in situations where the Protocol Stack only provides a byte-stream in situations where the Protocol Stack only provides a byte-stream
transport. transport.
o Receive a message: "Received" Event (Section 7.3.2.1), using * Receive a message: "Received" Event (Section 7.3.2.1), using
Message Framers (Section 7.1.2). Message Framers (Section 7.1.2).
o Information about partial message arrival: "ReceivedPartial" Event * Information about partial message arrival: "ReceivedPartial" Event
(Section 7.3.2.2). (Section 7.3.2.2).
o Notification of send failures: "Expired" Event (Section 7.2.2.2) * Notification of send failures: "Expired" Event (Section 7.2.2.2)
and "SendError" Event (Section 7.2.2.3). and "SendError" Event (Section 7.2.2.3).
o Notification that the stack has no more user data to send: * Notification that the stack has no more user data to send:
applications can obtain this information via the "Sent" Event applications can obtain this information via the "Sent" Event
(Section 7.2.2.1). (Section 7.2.2.1).
o Notification to a receiver that a partial message delivery has * Notification to a receiver that a partial message delivery has
been aborted: "ReceiveError" Event (Section 7.3.2.3). been aborted: "ReceiveError" Event (Section 7.3.2.3).
Authors' Addresses Authors' Addresses
Brian Trammell (editor) Brian Trammell (editor)
Google Switzerland GmbH Google Switzerland GmbH
Gustav-Gull-Platz 1 Gustav-Gull-Platz 1
8004 Zurich CH- 8004 Zurich
Switzerland Switzerland
Email: ietf@trammell.ch Email: ietf@trammell.ch
Michael Welzl (editor) Michael Welzl (editor)
University of Oslo University of Oslo
PO Box 1080 Blindern PO Box 1080 Blindern
0316 Oslo 0316 Oslo
Norway Norway
Email: michawe@ifi.uio.no Email: michawe@ifi.uio.no
Theresa Enghardt Theresa Enghardt
Netflix Netflix
121 Albright Way 121 Albright Way
Los Gatos, CA 95032 Los Gatos, CA 95032,
United States of America United States of America
Email: ietf@tenghardt.net Email: ietf@tenghardt.net
Godred Fairhurst Godred Fairhurst
University of Aberdeen University of Aberdeen
Fraser Noble Building Fraser Noble Building
Aberdeen, AB24 3UE Aberdeen, AB24 3UE
Scotland
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
URI: http://www.erg.abdn.ac.uk/ URI: http://www.erg.abdn.ac.uk/
Mirja Kuehlewind Mirja Kuehlewind
Ericsson Ericsson
Ericsson-Allee 1 Ericsson-Allee 1
Herzogenrath Herzogenrath
Germany Germany
skipping to change at page 80, line 4 skipping to change at page 80, line 8
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
URI: http://www.erg.abdn.ac.uk/ URI: http://www.erg.abdn.ac.uk/
Mirja Kuehlewind Mirja Kuehlewind
Ericsson Ericsson
Ericsson-Allee 1 Ericsson-Allee 1
Herzogenrath Herzogenrath
Germany Germany
Email: mirja.kuehlewind@ericsson.com Email: mirja.kuehlewind@ericsson.com
Colin Perkins Colin Perkins
University of Glasgow University of Glasgow
School of Computing Science School of Computing Science
Glasgow G12 8QQ Glasgow G12 8QQ
United Kingdom United Kingdom
Email: csp@csperkins.org Email: csp@csperkins.org
Philipp S. Tiesel Philipp S. Tiesel
TU Berlin SAP SE
Einsteinufer 25 Konrad-Zuse-Ring 10
10587 Berlin 14469 Potsdam
Germany Germany
Email: philipp@tiesel.net Email: philipp@tiesel.net
Christopher A. Wood Christopher A. Wood
Cloudflare Cloudflare
101 Townsend St 101 Townsend St
San Francisco San Francisco,
United States of America United States of America
Email: caw@heapingbits.net Email: caw@heapingbits.net
Tommy Pauly Tommy Pauly
Apple Inc. Apple Inc.
One Apple Park Way One Apple Park Way
Cupertino, California 95014 Cupertino, California 95014,
United States of America United States of America
Email: tpauly@apple.com Email: tpauly@apple.com
Kyle Rose Kyle Rose
Akamai Technologies, Inc. Akamai Technologies, Inc.
145 Broadway 145 Broadway
Cambridge, MA Cambridge, MA,
United States of America United States of America
Email: krose@krose.org Email: krose@krose.org
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