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Versions: (draft-yang-alto-path-vector) 00 01
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ALTO K. Gao
Internet-Draft Sichuan University
Intended status: Standards Track Y. Lee
Expires: 24 May 2021 Samsung
S. Randriamasy
Nokia Bell Labs
Y.R. Yang
Yale University
J. Zhang
Tongji University
20 November 2020
ALTO Extension: Path Vector
draft-ietf-alto-path-vector-13
Abstract
This document is an extension to the base Application-Layer Traffic
Optimization (ALTO) protocol. It extends the ALTO Cost Map service
and ALTO Property Map service so that the application can decide
which endpoint(s) to connect based on not only numerical/ordinal cost
values but also details of the paths. This is useful for
applications whose performance is impacted by specified components of
a network on the end-to-end paths, e.g., they may infer that several
paths share common links and prevent traffic bottlenecks by avoiding
such paths. This extension introduces a new abstraction called
Abstract Network Element (ANE) to represent these components and
encodes a network path as a vector of ANEs. Thus, it provides a more
complete but still abstract graph representation of the underlying
network(s) for informed traffic optimization among endpoints.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 May 2021.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Languages . . . . . . . . . . . . . . . . . . . 6
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Design Requirements . . . . . . . . . . . . . . . . . . . 7
4.2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2.1. Large-scale Data Analytics . . . . . . . . . . . . . 10
4.2.2. Context-aware Data Transfer . . . . . . . . . . . . . 10
4.2.3. CDN and Service Edge . . . . . . . . . . . . . . . . 10
5. Path Vector Extension: Overview . . . . . . . . . . . . . . . 11
5.1. Abstract Network Element . . . . . . . . . . . . . . . . 11
5.1.1. ANE Domain . . . . . . . . . . . . . . . . . . . . . 12
5.1.2. Ephemeral ANE and Persistent ANE . . . . . . . . . . 12
5.1.3. Property Filtering . . . . . . . . . . . . . . . . . 12
5.2. Path Vector Cost Type . . . . . . . . . . . . . . . . . . 13
5.3. Multipart Path Vector Response . . . . . . . . . . . . . 13
5.3.1. Identifying the Media Type of the Root Object . . . . 15
5.3.2. References to Part Messages . . . . . . . . . . . . . 15
5.3.3. Order and Completeness of Part Messages . . . . . . . 16
6. Specification: Basic Data Types . . . . . . . . . . . . . . . 16
6.1. ANE Name . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . 16
6.2.1. Entity Domain Type . . . . . . . . . . . . . . . . . 16
6.2.2. Domain-Specific Entity Identifier . . . . . . . . . . 16
6.2.3. Hierarchy and Inheritance . . . . . . . . . . . . . . 17
6.2.4. Media Type of Defining Resource . . . . . . . . . . . 17
6.3. ANE Property Name . . . . . . . . . . . . . . . . . . . . 17
6.4. Initial ANE Property Types . . . . . . . . . . . . . . . 17
6.4.1. New ANE Property Type: Maximum Reservable
Bandwidth . . . . . . . . . . . . . . . . . . . . . . 18
6.4.2. New ANE Property Type: Persistent Entity ID . . . . . 19
6.5. Path Vector Cost Type . . . . . . . . . . . . . . . . . . 19
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6.5.1. Cost Metric: ane-path . . . . . . . . . . . . . . . . 19
6.5.2. Cost Mode: array . . . . . . . . . . . . . . . . . . 20
6.6. Part Resource ID . . . . . . . . . . . . . . . . . . . . 20
7. Specification: Service Extensions . . . . . . . . . . . . . . 20
7.1. Multipart Filtered Cost Map for Path Vector . . . . . . . 20
7.1.1. Media Type . . . . . . . . . . . . . . . . . . . . . 20
7.1.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 21
7.1.3. Accept Input Parameters . . . . . . . . . . . . . . . 21
7.1.4. Capabilities . . . . . . . . . . . . . . . . . . . . 22
7.1.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1.6. Response . . . . . . . . . . . . . . . . . . . . . . 22
7.2. Multipart Endpoint Cost Service for Path Vector . . . . . 26
7.2.1. Media Type . . . . . . . . . . . . . . . . . . . . . 26
7.2.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 26
7.2.3. Accept Input Parameters . . . . . . . . . . . . . . . 26
7.2.4. Capabilities . . . . . . . . . . . . . . . . . . . . 27
7.2.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 27
7.2.6. Response . . . . . . . . . . . . . . . . . . . . . . 27
8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.1. Example: Information Resource Directory . . . . . . . . . 30
8.2. Example: Multipart Filtered Cost Map . . . . . . . . . . 32
8.3. Example: Multipart Endpoint Cost Resource . . . . . . . . 33
8.4. Example: Incremental Updates . . . . . . . . . . . . . . 36
9. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 37
9.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 37
9.2. Compatibility with Multi-Cost Extension . . . . . . . . . 37
9.3. Compatibility with Incremental Update . . . . . . . . . . 37
9.4. Compatibility with Cost Calendar . . . . . . . . . . . . 37
10. General Discussions . . . . . . . . . . . . . . . . . . . . . 38
10.1. Constraint Tests for General Cost Types . . . . . . . . 38
10.2. General Multipart Resources Query . . . . . . . . . . . 39
11. Security Considerations . . . . . . . . . . . . . . . . . . . 39
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
12.1. ALTO Entity Domain Type Registry . . . . . . . . . . . . 40
12.2. ALTO Entity Property Type Registry . . . . . . . . . . . 40
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 41
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 41
14.1. Normative References . . . . . . . . . . . . . . . . . . 41
14.2. Informative References . . . . . . . . . . . . . . . . . 42
Appendix A. Changes since -12 . . . . . . . . . . . . . . . . . 44
Appendix B. Changes since -11 . . . . . . . . . . . . . . . . . 44
Appendix C. Changes since -10 . . . . . . . . . . . . . . . . . 44
Appendix D. Changes since -09 . . . . . . . . . . . . . . . . . 45
Appendix E. Changes since -08 . . . . . . . . . . . . . . . . . 45
Appendix F. Changes Since Version -06 . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
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1. Introduction
Network performance metrics are crucial to the Quality of Experience
(QoE) of today's applications. The ALTO protocol allows Internet
Service Providers (ISPs) to provide guidance, such as topological
distance between different end hosts, to overlay applications. Thus,
the overlay applications can potentially improve the QoE by better
orchestrating their traffic to utilize the resources in the
underlying network infrastructure.
Existing ALTO Cost Map and Endpoint Cost Service provide only cost
information on an end-to-end path defined by its <source,
destination> endpoints: The base protocol [RFC7285] allows the
services to expose the topological distances of end-to-end paths,
while various extensions have been proposed to extend the capability
of these services, e.g., to express other performance metrics
[I-D.ietf-alto-performance-metrics], to query multiple costs
simultaneously [RFC8189], and to obtain the time-varying values
[I-D.ietf-alto-cost-calendar].
While the existing extensions are sufficient for many overlay
applications, however, the QoE of some overlay applications depends
not only on the cost information of end-to-end paths, but also on
particular components of a network on the paths and their properties.
For example, job completion time, which is an important QoE metric
for a large-scale data analytics application, is impacted by shared
bottleneck links inside the carrier network. We refer to such
components of a network as Abstract Network Elements (ANE).
Predicting such information can be very complex without the help of
the ISP [AAAI2019]. With proper guidance from the ISP, an overlay
application may be able to schedule its traffic for better QoE. In
the meantime, it may be helpful as well for ISPs if applications
could avoid using bottlenecks or challenging the network with poorly
scheduled traffic.
Despite the benefits, ISPs are not likely to expose details on their
network paths: first for the sake of confidentiality, second because
it may result in a huge volume and overhead, and last because it is
difficult for ISPs to figure out what information and what details an
application needs. Likewise, applications do not necessarily need
all the network path details and are likely not able to understand
them.
Therefore, it is beneficial for both parties if an ALTO server
provides ALTO clients with an "abstract network state" that provides
the necessary details to applications, while hiding the network
complexity and confidential information. An "abstract network state"
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is a selected set of abstract representations of Abstract Network
Elements traversed by the paths between <source, destination> pairs
combined with properties of these Abstract Network Elements that are
relevant to the overlay applications' QoE. Both an application via
its ALTO client and the ISP via the ALTO server can achieve better
confidentiality and resource utilization by appropriately abstracting
relevant Abstract Network Elements. The pressure on the server
scalability can also be reduced by combining Abstract Network
Elements and their properties in a single response.
This document extends [RFC7285] to allow an ALTO server convey
"abstract network state", for paths defined by their <source,
destination> pairs. To this end, it introduces a new cost type
called "Path Vector". A Path Vector is an array of identifiers that
each identifies an Abstract Network Element, which can be associated
with various properties. The associations between ANEs and their
properties are encoded in an ALTO information resource called Unified
Property Map, which is specified in
[I-D.ietf-alto-unified-props-new].
For better confidentiality, this document aims to minimize
information exposure. In particular, this document enables and
recommends that first ANEs are constructed on demand, and second an
ANE is only associated with properties that are requested by an ALTO
client. A Path Vector response involves two ALTO Maps: the Cost Map
that contains the Path Vector results and the up-to-date Unified
Property Map that contains the properties requested for these ANEs.
To enforce consistency and improve server scalability, this document
uses the "multipart/related" message defined in [RFC2387] to return
the two maps in a single response.
The rest of the document is organized as follows. Section 3
introduces the extra terminologies that are used in this document.
Section 4 uses an illustrative example to introduce the additional
requirements of the ALTO framework, and discusses potential use
cases. Section 5 gives an overview of the protocol design.
Section 6 and Section 7 specify the Path Vector extension to the ALTO
IRD and the information resources, with some concrete examples
presented in Section 8. Section 9 discusses the backward
compatibility with the base protocol and existing extensions.
Security and IANA considerations are discussed in Section 11 and
Section 12 respectively.
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2. Requirements Languages
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
When the words appear in lower case, they are to be interpreted with
their natural language meanings.
3. Terminology
NOTE: This document depends on the Unified Property Map extension
[I-D.ietf-alto-unified-props-new] and should be processed after the
Unified Property Map document.
This document extends the ALTO base protocol [RFC7285] and the
Unified Property Map extension [I-D.ietf-alto-unified-props-new]. In
addition to the terms defined in these documents, this document also
uses the following additional terms:
* Abstract Network Element (ANE): An Abstract Network Element is an
abstract representation for a component in a network that handle
data packets and whose properties can potentially have an impact
on the end-to-end performance of traffic. An ANE can be a
physical device such as a router, a link or an interface, or an
aggregation of devices such as a subnetwork, or a data center.
The definition of Abstract Network Element is similar to Network
Element defined in [RFC2216] in the sense that they both provide
an abstract representation of particular components of a network.
However, they have different criteria on how these particular
components are selected. Specifically, Network Element requires
the components to be potentially capable of exercising QoS
control, while Abstract Network Element only requires the
components to have an impact on the end-to-end performance.
* ANE Name: An ANE can be constructed either statically in advance
or on demand based on the requested information. Thus, different
ANEs may only be valid within a particular scope, either ephemeral
or persistent. Within each scope, an ANE is uniquely identified
by an ANE Name, as defined in Section 6.1. Note that an ALTO
client must not assume ANEs in different scopes but with the same
ANE Name refer to the same component(s) of the network.
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* Path Vector: A Path Vector, or an ANE Path Vector, is a JSON array
of ANE Names. It is a generalization of BGP path vector. While
standard BGP path vector specifies a sequence of autonomous
systems for a destination IP prefix, the Path Vector defined in
this extension specifies a sequence of ANEs either for a source
PID and a destination PID as in a cost map or for a source
endpoint and a destination endpoint as in an endpoint cost map.
* Path Vector resource: A Path Vector resource refers to an ALTO
resource which supports the extension defined in this document.
* Path Vector cost type: The Path Vector cost type is a special cost
type, which is specified in Section 6.5. When this cost type is
present in an IRD entry, it indicates that the information
resource is a Path Vector resource. When this cost type is
present in a Cost Map or an Endpoint Cost Map, it indicates each
cost value must be interpreted as a Path Vector.
* Path Vector request: A Path Vector request refers to the POST
message sent to an ALTO Path Vector resource.
* Path Vector response: A Path Vector response refers to the
multipart/related message returned by a Path Vector resource.
4. Problem Statement
4.1. Design Requirements
This section gives an illustrative example of how an overlay
application can benefit from the Path Vector extension.
Assume that an application has control over a set of flows, which may
go through shared links or switches and share a bottleneck. The
application hopes to schedule the traffic among multiple flows to get
better performance. The capacity region information for those flows
will benefit the scheduling. However, existing cost maps can not
reveal such information.
Specifically, consider a network as shown in Figure 1. The network
has 7 switches (sw1 to sw7) forming a dumb-bell topology. Switches
sw1/sw3 provide access on one side, sw2/sw4 provide access on the
other side, and sw5-sw7 form the backbone. Endhosts eh1 to eh4 are
connected to access switches sw1 to sw4 respectively. Assume that
the bandwidth of link eh1 -> sw1 and link sw1 -> sw5 are 150 Mbps,
and the bandwidth of the rest links are 100 Mbps.
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+------+
| |
--+ sw6 +--
/ | | \
PID1 +-----+ / +------+ \ +-----+ PID2
eh1__| |_ / \ ____| |__eh2
1.2.3.4 | sw1 | \ +--|---+ +---|--+ / | sw2 | 2.3.4.5
+-----+ \ | | | |/ +-----+
\_| sw5 +---------+ sw7 |
PID3 +-----+ / | | | |\ +-----+ PID4
eh3__| |__/ +------+ +------+ \____| |__eh4
3.4.5.6 | sw3 | | sw4 | 4.5.6.7
+-----+ +-----+
Figure 1: Raw Network Topology
The single-node ALTO topology abstraction of the network is shown in
Figure 2.
+----------------------+
{eh1} | | {eh2}
PID1 | | PID2
+------+ +------+
| |
| |
{eh3} | | {eh4}
PID3 | | PID4
+------+ +------+
| |
+----------------------+
Figure 2: Base Single-Node Topology Abstraction
Consider an application overlay (e.g., a large-scale data analytics
system) which wants to optimize the total throughput of the traffic
among a set of end host <source, destination> pairs, say eh1 -> eh2
and eh1 -> eh4. The application can request a cost map providing
end-to-end available bandwidth, using "availbw" as cost-metric and
"numerical" as cost-mode.
The application will receive from the ALTO server that the bandwidth
of eh1 -> eh2 and eh1 -> eh4 are both 100 Mbps. But this information
is not enough to determine the optimal total throughput. Consider
the following two cases:
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* Case 1: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw6 ->
sw7 -> sw2 -> eh2 and eh1 -> eh4 uses path eh1 -> sw1 -> sw5 ->
sw7 -> sw4 -> eh4, then the application will obtain 150 Mbps at
most.
* Case 2: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw7 ->
sw2 -> eh2 and eh1 -> eh4 uses the path eh1 -> sw1 -> sw5 -> sw7
-> sw4 -> eh4, then the application will obtain only 100 Mbps at
most.
To allow applications to distinguish the two aforementioned cases,
the network needs to provide more details. In particular:
* For eh1 -> eh2, the ALTO server must give more details which is
critical for the overlay application to distinguish between Case 1
and Case 2 and to compute the optimal total throughput
accordingly.
* The ALTO server must allow the client to distinguish the common
ANE shared by eh1 -> eh2 and eh1 -> eh4, e.g., eh1 - sw1 and sw1 -
sw5 in Case 1.
* The ALTO server must give details on the properties of the ANEs
used by eh1 -> eh2 and eh1 -> eh4, e.g., the available bandwidth
between eh1 - sw1, sw1 - sw5, sw5 - sw7, sw5 - sw6, sw6 - sw7, sw7
- sw2, sw7 - sw4, sw2 - eh2, sw4 - eh4 in Case 1.
In general, we can conclude that to support the multiple flow
scheduling use case, the ALTO framework must be extended to satisfy
the following additional requirements:
AR1: An ALTO server must provide essential information on ANEs on
the path of a <source, destination> pair that are critical to the
QoE of the overlay application.
AR2: An ALTO server must provide essential information on how the
paths of different <source, destination> pairs share a common ANE.
AR3: An ALTO server must provide essential information on the
properties associated to the ANEs.
The Path Vector extension defined in this document propose a solution
to provide these details.
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4.2. Use Cases
While the multiple flow scheduling problem is used to help identify
the additional requirements, the Path Vector extension can be applied
to a wide range of applications. This section highlights some real
use cases that are reported.
4.2.1. Large-scale Data Analytics
One potential use case of the Path Vector extension is for large-
scale data analytics such as [SENSE] and [LHC], where data of
Gigabytes, Terabytes and even Petabytes are transferred. For these
applications, the QoE is usually measured as the job completion time,
which is related to the completion time of the slowest data transfer.
With the Path Vector extension, an ALTO client can identify
bottlenecks inside the network. Therefore, the overlay application
can make optimal traffic distribution or resource reservation (i.e.,
proportional to the size of the transferred data), leading to optimal
job completion time and network resource utilization.
4.2.2. Context-aware Data Transfer
It is getting important to know the capabilities of various ANEs
between two end hosts, especially in the mobile environment. With
the Path Vector extension, an ALTO client may query the "network
context" information, i.e., whether the two hosts are connected to
the access network through a wireless link or a wire, and the
capabilities of the access network. Thus, the client may use
different data transfer mechanisms, or even deploy different 5G User
Plane Functions (UPF) [I-D.ietf-dmm-5g-uplane-analysis] to optimize
the data transfer.
4.2.3. CDN and Service Edge
A growing trend in today's applications is to bring storage and
computation closer to the end user for better QoE, such as Content
Delivery Network (CDN), AR/VR, and cloud gaming, as reported in
various documents ([I-D.contreras-alto-service-edge],
[I-D.huang-alto-mowie-for-network-aware-app], and
[I-D.yang-alto-deliver-functions-over-networks]).
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With the Path Vector extension, an ALTO server can selectively reveal
the CDNs and service edges that reside along the paths between
different end hosts, together with their properties such as available
Service Level Agreement (SLA) plans. Otherwise, the ALTO client may
have to make multiple queries and potentially with the complete list
of CDNs and/or service edges. While both approaches offer the same
information, making multiple queries introduces larger delay and more
overhead on both the ALTO server and the ALTO client.
5. Path Vector Extension: Overview
This section gives a non-normative overview of the Path Vector
extension. It is assumed that readers are familiar with both the
base protocol [RFC7285] and the Unified Property Map extension
[I-D.ietf-alto-unified-props-new].
To satisfies the additional requirements, this extension:
1. introduces Abstract Network Element (ANE) as the abstraction of
components in a network whose properties may have an impact on
the end-to-end performance of the traffic handled by those
component,
2. extends the Cost Map and Endpoint Cost Service to convey the ANEs
traversed by the path of a <source, destination> pair as Path
Vectors,
3. uses the Unified Property Map to convey the association between
the ANEs and their properties.
Thus, an ALTO client can learn about the ANEs that are critical to
the QoE of a <source, destination> pair by investigating the
corresponding Path Vector value (AR1), identify common ANEs if an ANE
appears in the Path Vectors of multiple <source, destination> pairs
(AR2), and retrieve the properties of the ANEs by searching the
Unified Property Map (AR3).
5.1. Abstract Network Element
This extension introduces Abstract Network Element (ANE) as an
indirect and network-agnostic way to specify a component or an
aggregation of components of a network whose properties have an
impact on the end-to-end performance for traffic between a source and
a destination.
When an ANE is defined by the ALTO server, it MUST be assigned an
identifier, i.e., string of type ANEName as specified in Section 6.1,
and a set of associated properties.
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5.1.1. ANE Domain
In this extension, the associations between ANE and the properties
are conveyed in a Unified Property Map. Thus, they must follow the
mechanisms specified in the [I-D.ietf-alto-unified-props-new].
Specifically, this document defines a new entity domain called "ane"
as specified in Section 6.2 and defines two initial properties for
the "ane" domain.
5.1.2. Ephemeral ANE and Persistent ANE
For different requests, there can be different ways of grouping
components of a network and assigning ANEs. For example, an ALTO
server may define an ANE for each aggregated bottleneck link between
the sources and destinations specified in the request. As the
aggregated bottleneck links vary for different combinations of
sources and destinations, the ANEs are ephemeral and are no longer
valid after the request completes. Thus, the scope of ephemeral ANEs
are limited to the corresponding Path Vector response.
While ephemeral ANEs returned by a Path Vector response do not exist
beyond that response, some of them may represent entities that are
persistent and defined in a standalone Property Map. Indeed, it may
be useful for clients to occasionally query properties on persistent
entities, without caring about the path that traverses them.
Persistent entities have a persistent ID that is registered in a
Property Map, together with their properties.
5.1.3. Property Filtering
Resource-constrained ALTO clients may benefit from the filtering of
Path Vector query results at the ALTO server, as an ALTO client may
only require a subset of the available properties.
Specifically, the available properties for a given resource are
announced in the Information Resource Directory as a new capability
called "ane-property-names". The selected properties are specified
in a filter called "ane-property-names" in the request body, and the
response MUST include and only include the selected properties for
the ANEs in the response.
The "ane-property-names" capability for Cost Map and for Endpoint
Cost Service are specified in Section 7.1.4 and Section 7.2.4
respectively. The "ane-property-names" filter for Cost Map and
Endpoint Cost Service are specified in Section 7.1.3 and
Section 7.2.3 accordingly.
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5.2. Path Vector Cost Type
For an ALTO client to correctly interpret the Path Vector, this
extension specifies a new cost type called the Path Vector cost type,
which must be included both in the Information Resource Directory and
the ALTO Cost Map or Endpoint Cost Map so that an ALTO client can
correctly interpret the cost values.
The Path Vector cost type must convey both the interpretation and
semantics in the "cost-mode" and "cost-metric" respectively.
Unfortunately, a single "cost-mode" value cannot fully specify the
interpretation of a Path Vector, which is a compound data type. For
example, in programming languages such as Java, a Path Vector will
have the type of JSONArray[ANEName].
Instead of extending the "type system" of ALTO, this document takes a
simple and backward compatible approach. Specifically, the "cost-
mode" of the Path Vector cost type is "array", which indicates the
value is a JSON array. Then, an ALTO client must check the value of
the "cost-metric". If the value is "ane-path", meaning the JSON
array should be further interpreted as a path of ANENames.
The Path Vector cost type is specified in Section 6.5.
5.3. Multipart Path Vector Response
For a basic ALTO information resource, a response contains only one
type of ALTO resources, e.g., Network Map, Cost Map, or Property Map.
Thus, only one round of communication is required: An ALTO client
sends a request to an ALTO server, and the ALTO server returns a
response, as shown in Figure 3.
ALTO client ALTO server
|-------------- Request ---------------->|
|<------------- Response ----------------|
Figure 3: A Typical ALTO Request and Response
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The Path Vector extension, on the other hand, involves two types of
information resources: Path Vectors conveyed in a Cost Map or an
Endpoint Cost Map, and ANE properties conveyed in a Unified Property
Map. Instead of two consecutive message exchanges, the Path Vector
extension enforces one round of communication. Specifically, the
ALTO client MUST include the source and destination pairs and the
requested ANE properties in a single request, and the ALTO server
MUST return a single response containing both the Path Vectors and
properties associated with the ANEs in the Path Vectors, as shown in
Figure 4. Since the two parts are bundled together in one response
message, their orders are interchangeable. See Section 7.1.6 and
Section 7.2.6 for details.
ALTO client ALTO server
|------------- PV Request -------------->|
|<----- PV Response (Cost Map Part) -----|
|<--- PV Response (Property Map Part) ---|
Figure 4: The Path Vector Extension Request and Response
This design is based on the following considerations:
1. Since ANEs may be constructed on demand, and potentially based on
the requested properties (See Section 5.1 for more details). If
sources and destinations are not in the same request as the
properties, an ALTO server either cannot construct ANEs on-
demand, or must wait until both requests are received.
2. As ANEs may be constructed on demand, mappings of each ANE to its
underlying network devices and resources can be specific to the
request. In order to respond to the Property Map request
correctly, an ALTO server must store the mapping of each Path
Vector request until the client fully retrieves the property
information. The "stateful" behavior may substantially harm the
server scalability and potentially lead to Denial-of-Service
attacks.
One approach to realize the one-round communication is to define a
new media type to contain both objects, but this violates modular
design. This document follows the standard-conforming usage of
"multipart/related" media type defined in [RFC2387] to elegantly
combine the objects. Path Vectors are encoded as a Cost Map or an
Endpoint Cost Map, and the Property Map is encoded as a Unified
Propert Map. They are encapsulated as parts of a multipart message.
The modular composition allows ALTO servers and clients to reuse the
data models of the existing information resources. Specifically,
this document addresses the following practical issues using
"multipart/related".
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5.3.1. Identifying the Media Type of the Root Object
ALTO uses media type to indicate the type of an entry in the
Information Resource Directory (IRD) (e.g., "application/alto-
costmap+json" for Cost Map and "application/alto-endpointcost+json"
for Endpoint Cost Map). Simply putting "multipart/related" as the
media type, however, makes it impossible for an ALTO client to
identify the type of service provided by related entries.
To address this issue, this document uses the "type" parameter to
indicate the root object of a multipart/related message. For a Cost
Map resource, the "media-type" in the IRD entry must be "multipart/
related" with the parameter "type=application/alto-costmap+json"; for
an Endpoint Cost Service, the parameter must be "type=application/
alto-endpointcost+json".
5.3.2. References to Part Messages
The ALTO SSE extension (see [I-D.ietf-alto-incr-update-sse]) uses
"client-id" to demultiplex push updates. However, "client-id" is
provided for each request, which introduces ambiguity when applying
SSE to a Path Vector resource.
To address this issue, an ALTO server must assign a unique identifier
to each part of the "multipart/related" response message. This
identifier, referred to as a Part Resource ID (See Section 6.6 for
details), must be present in the part message's "Resource-Id" header.
The MIME part header must also contain the "Content-Type" header,
whose value is the media type of the part (e.g., "application/alto-
costmap+json", "application/alto-endpointcost+json", or "application/
alto-propmap+json").
If an ALTO server provides incremental updates for this Path Vector
resource, it must generate incremental updates for each part
separately. The client-id must have the following format:
pv-client-id '.' part-resource-id
where pv-client-id is the client-id assigned to the Path Vector
request, and part-resource-id is the "Resource-Id" header value of
the part. The media-type must match the "Content-Type" of the part.
The same problem applies to the part messages as well. The two parts
must contain a version tag, which SHOULD contain a unique Resource
ID. This document requires the resource-id in a Version Tag to have
the following format:
pv-resource-id '.' part-resource-id
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where pv-resource-id is the resource ID of the Path Vector resource
in the IRD entry, and the part-resource-id has the same value as the
"Resource-Id" header of the part.
5.3.3. Order and Completeness of Part Messages
According to [RFC2387], the Path Vector part, whose media type is the
same as the "type" parameter of the multipart response message, is
the root object. Thus, it is the element the application processes
first. Even though the "start" parameter allows it to be placed
anywhere in the part sequence, it is RECOMMENDED that the parts
arrive in the same order as they are processed, i.e., the Path Vector
part is always put as the first part, followed by the property map
part. It is also RECOMMENDED that when doing so, an ALTO server
SHOULD NOT set the "start" parameter, which implies the first part is
the root object.
A complete and valid response MUST include both the Path Vector part
and the Property Map part in the multipart message.
6. Specification: Basic Data Types
6.1. ANE Name
An ANE Name is encoded as a JSON string with the same format as that
of the type PIDName (Section 10.1 of [RFC7285]).
The type ANEName is used in this document to indicate a string of
this format.
6.2. ANE Domain
The ANE domain associates property values with the Abstract Network
Elements in a Property Map. Accordingly, the ANE domain always
depends on a Property Map.
6.2.1. Entity Domain Type
ane
6.2.2. Domain-Specific Entity Identifier
The entity identifiers are the ANE Names in the associated Property
Map.
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6.2.3. Hierarchy and Inheritance
There is no hierarchy or inheritance for properties associated with
ANEs.
6.2.4. Media Type of Defining Resource
When resource specific domains are defined with entities of domain
type "ane", the defining resource for entity domain type "pid" MUST
be a Property Map. The media type of defining resources for the "ane"
domain is:
application/alto-propmap+json
Specifically, for ephemeral ANEs that appear in a Path Vector
response, their entity domain names MUST be ".ane" and the defining
resource of these ANEs is the Property Map part of the multipart
response. Meanwhile, for persistent ANEs whose entity domain name
has the format of "PROPMAP.ane" where PROPMAP is the name of a
Property Map resource, PROPMAP is the defining resource of these
ANEs. Persistent entities are "persistent" because standalone
queries can be made by an ALTO client to their defining resources
when the connection to the Path Vector service is closed.
For example, the defining resource of ".ane:NET1" is the Property Map
part that contains this identifier, i.e., the ANE entity ".ane:NET1"
is self-defined. The defining resource of "dc-props.ane:DC1" is the
Property Map with the resource ID "dc-props".
6.3. ANE Property Name
An ANE Property Name is encoded as a JSON string with the same format
as that of Entity Property Name (Section 5.2.2 of
[I-D.ietf-alto-unified-props-new]).
6.4. Initial ANE Property Types
In this document, two initial ANE property types are specified, "max-
reservable-bandwidth" and "persistent-entity-id".
Note that the two property types defined in this document do not
depend on any information resource, so their ResourceID part must be
empty.
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----- L1
/
PID1 +---------------+ 10 Gbps +----------+ PID3
1.2.3.0/24+---+ +-----------+ +---------+ +---+3.4.5.0/24
| | MEC1 | | | |
| +-----------+ | +-----+ |
PID2 | | | +----------+
2.3.4.0/24+---+ | | NET3
| | | 15 Gbps
| | | \
+---------------+ | -------- L2
NET1 |
+---------------+
| +-----------+ | PID4
| | MEC2 | +---+4.5.6.0/24
| +-----------+ |
+---------------+
NET2
Figure 5: Examples of ANE Properties
In this document, Figure 5 is used to illustrate the use of the two
initial ANE property types. There are 3 sub-networks (NET1, NET2 and
NET3) and two interconnection links (L1 and L2). It is assumed that
each sub-network has sufficiently large bandwidth to be reserved.
6.4.1. New ANE Property Type: Maximum Reservable Bandwidth
Identifier: "max-reservable-bandwidth"
Intended Semantics: The maximum reservable bandwidth property stands
for the maximum bandwidth that can be reserved for all the traffic
that traverses an ANE. The value MUST be encoded as a non-
negative numerical cost value as defined in Section 6.1.2.1 of
[RFC7285] and the unit is bit per second. If this property is
requested but not present in an ANE, it MUST be interpreted as
that the ANE does not support bandwidth reservation.
Security Considerations: ALTO entity properties expose information
to ALTO clients. ALTO service providers should be made aware of
the security ramifications related to the exposure of an entity
property.
To illustrate the use of "max-reservable-bandwidth", consider the
network in Figure 5. An ALTO server can create an ANE for each
interconnection link, where the initial value for "max-reservable-
bandwidth" is the link capacity.
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6.4.2. New ANE Property Type: Persistent Entity ID
Identifier: "persistent-entity-id"
Intended Semantics: The persistent entity ID property is the entity
identifier of the persistent ANE which an ephemeral ANE presents
(See Section 5.1.2 for details). The value of this property is
encoded with the format defined in Section 5.1.3 of
[I-D.ietf-alto-unified-props-new]. In this format, the entity ID
combines:
* a defining information resource for the ANE on which a
"persistent-entity-id" is queried, which is the property map
defining the ANE as a persistent entity, together with the
properties
* the persistent name of the ANE in this property map
With this format, the client has all the needed information for
further standalone query properties on the persistent ANE.
Security Considerations: ALTO entity properties expose information
to ALTO clients. ALTO service providers should be made aware of
the security ramifications related to the exposure of an entity
property.
To illustrate the use of "persistent-entity-id", consider the network
in Figure 5. Assume the ALTO server has a Property Map resource
called "mec-props" that defines persistent ANEs "MEC1" and "MEC2"
that represent the corresponding mobile edge computing (MEC)
clusters. Since MEC1 is associated with NET1, the "persistent-
entity-id" of the ephemeral ANE ".ane:NET1" is the persistent entity
id "mec-props.ane:MEC1".
6.5. Path Vector Cost Type
This document defines a new cost type, which is referred to as the
"Path Vector" cost type. An ALTO server MUST offer this cost type if
it supports the Path Vector extension.
6.5.1. Cost Metric: ane-path
The cost metric "ane-path" indicates the value of such a cost type
conveys an array of ANE names, where each ANE name uniquely
represents an ANE traversed by traffic from a source to a
destination.
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An ALTO client MUST interpret the Path Vector as if the traffic
between a source and a destination logically traverses the ANEs in
the same order as they appear in the Path Vector. However, under
certain scenarios where the traversal order is not crucial, an ALTO
server implementation may choose to not follow strictly the physical
traversal order and may even obfuscate the order intentionally, for
security and performance considerations. For example, in the multi-
flow bandwidth reservation use case as introduced in Section 4, only
the available bandwidth of the shared bottleneck link is crucial, and
the ALTO server may change the order of links appearing in the Path
Vector response.
6.5.2. Cost Mode: array
The cost mode "array" indicates that every cost value in a Cost Map
or an Endpoint Cost Map MUST be interpreted as a JSON array object.
Note that this cost mode only requires the cost value to be a JSON
array of JSONValue. However, an ALTO server that enables this
extension MUST return a JSON array of ANEName (Section 6.1) when the
cost metric is "ane-path".
6.6. Part Resource ID
A Part Resource ID is encoded as a JSON string with the same format
as that of the type ResourceID (Section 10.2 of [RFC7285]).
Even though the client-id assigned to a Path Vector request and the
Part Resource ID MAY contain up to 64 characters by their own
definition, their concatenation (see Section 5.3.2) MUST also conform
to the same length constraint. The same requirement applies to the
resource ID of the Path Vector resource, too. Thus, it is
RECOMMENDED to limit the length of resource ID and client ID related
to a Path Vector resource to 31 characters.
7. Specification: Service Extensions
7.1. Multipart Filtered Cost Map for Path Vector
This document introduces a new ALTO resource called multipart
filtered cost map resource, which allows an ALTO server to provide
other ALTO resources associated to the cost map resource in the same
response.
7.1.1. Media Type
The media type of the multipart filtered cost map resource is
"multipart/related;type=application/alto-costmap+json".
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7.1.2. HTTP Method
The multipart filtered cost map is requested using the HTTP POST
method.
7.1.3. Accept Input Parameters
The input parameters of the multipart filtered cost map are supplied
in the body of an HTTP POST request. This document extends the input
parameters to a filtered cost map with a data format indicated by the
media type "application/alto-costmapfilter+json", which is a JSON
object of type PVReqFilteredCostMap, where:
object {
[EntityPropertyName ane-property-names<0..*>;]
} PVReqFilteredCostMap : ReqFilteredCostMap;
with fields:
ane-property-names: A list of properties that are associated with
the ANEs. Each property in this list MUST match one of the
supported ANE properties indicated in the resource's "ane-
property-names" capability. If the field is NOT present, it MUST
be interpreted as an empty list, indicating that the ALTO server
MUST NOT return any property in the Unified Property part.
Example: Consider the network in Figure 1. If an ALTO client wants
to query the "max-reservable-bandwidth" between PID1 and PID2, it can
submit the following request.
POST /costmap/pv HTTP/1.1
Host: alto.example.com
Accept: multipart/related;type=application/alto-costmap+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-costmapfilter+json
{
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"pids": {
"srcs": [ "PID1" ],
"dsts": [ "PID2" ]
},
"ane-property-names": [ "max-reservable-bandwidth" ]
}
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7.1.4. Capabilities
The multipart filtered cost map resource extends the capabilities
defined in Section 11.3.2.4 of [RFC7285]. The capabilities are
defined by a JSON object of type PVFilteredCostMapCapabilities:
object {
[EntityPropertyName ane-property-names<0..*>;]
} PVFilteredCostMapCapabilities : FilteredCostMapCapabilities;
with fields:
cost-type-names: The "cost-type-names" field MUST only include the
Path Vector cost type, unless explicitly documented by a future
extension. This also implies that the Path Vector cost type MUST
be defined in the "cost-types" of the Information Resource
Directory's "meta" field.
cost-constraints: If the "cost-type-names" field includes the Path
Vector cost type, "cost-constraints" field MUST be "false" or not
present unless specifically instructed by a future document.
testable-cost-type-names: If the "cost-type-names" field includes
the Path Vector cost type, the Path Vector cost type MUST NOT be
included in the "testable-cost-type-names" field unless
specifically instructed by a future document.
ane-property-names: Defines a list of ANE properties that can be
returned. If the field is NOT present, it MUST be interpreted as
an empty list, indicating the ALTO server cannot provide any ANE
property.
7.1.5. Uses
This member MUST include the resource ID of the network map based on
which the PIDs are defined. If this resource supports "persistent-
entity-id", it MUST also include the defining resources of persistent
ANEs that may appear in the response.
7.1.6. Response
The response MUST indicate an error, using ALTO protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is
invalid.
The "Content-Type" header of the response MUST be "multipart/related"
as defined by [RFC2387] with the following parameters:
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type: The type parameter MUST be "application/alto-costmap+json".
Note that [RFC2387] permits both parameters with and without the
double quotes.
start: The start parameter is as defined in [RFC2387]. If present,
it MUST have the same value as the "Resource-Id" header of the
Path Vector part.
boundary: The boundary parameter is as defined in [RFC2387].
The body of the response MUST consist of two parts:
* The Path Vector part MUST include "Resource-Id" and "Content-Type"
in its header. The value of "Resource-Id" MUST has the format of
a Part Resource ID. The "Content-Type" MUST be "application/alto-
costmap+json".
The body of the Path Vector part MUST be a JSON object with the
same format as defined in Section 11.2.3.6 of [RFC7285]. The JSON
object MUST include the "vtag" field in the "meta" field, which
provides the version tag of the returned cost map. The resource
ID of the version tag MUST follow the format in Section 5.3.2.
The "meta" field MUST also include the "dependent-vtags" field,
whose value is a single-element array to indicate the version tag
of the network map used, where the network map is specified in the
"uses" attribute of the multipart filtered cost map resource in
IRD.
* The Unified Property Map part MUST also include "Resource-Id" and
"Content-Type" in its header. The value of "Resource-Id" has the
format of a Part Resource ID. The "Content-Type" MUST be
"application/alto-propmap+json".
The body of the Unified Property Map part MUST be a JSON object
with the same format as defined in Section 4.6 of
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include
the "dependent-vtags" field in the "meta" field. The value of the
"dependent-vtags" field MUST be an array of VersionTag objects as
defined by Section 10.3 of [RFC7285]. The "vtag" of the Path
Vector part MUST be included in the "dependent-vtags". If
"persistent-entity-id" is requested, the version tags of the
dependent resources that MAY expose the entities in the response
MUST also be included. The PropertyMapData has one member for
each ANEName that appears in the Path Vector part, which is an
entity identifier belonging to the self-defined entity domain as
defined in Section 5.1.2.3 of [I-D.ietf-alto-unified-props-new].
The EntityProps has one member for each property requested by an
ALTO client if applicable.
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If the "start" parameter is not present, the Path Vector part MUST be
the first part in the multipart response. If any part is NOT
present, the client MUST discard the received information and send
another request if necessary.
Example: Consider the network in Figure 1. The response of the
example request in Section 7.1.3 is as follows, where "ANE1"
represents the aggregation of all the switches in the network.
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HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: multipart/related; boundary=example-1;
type=application/alto-costmap+json
--example-1
Resource-Id: costmap
Content-Type: application/alto-costmap+json
{
"meta": {
"vtag": {
"resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
},
"dependent-vtags": [
{
"resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f6228"
}
],
"cost-type": { "cost-mode": "array", "cost-metric": "ane-path" }
},
"cost-map": {
"PID1": { "PID2": ["ANE1"] }
}
}
--example-1
Resource-Id: propmap
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
}
]
},
"property-map": {
".ane:ANE1": { "max-reservable-bandwidth": 100000000 }
}
}
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7.2. Multipart Endpoint Cost Service for Path Vector
This document introduces a new ALTO resource called multipart
endpoint cost resource, which allows an ALTO server to provide other
ALTO resources associated to the endpoint cost resource in the same
response.
7.2.1. Media Type
The media type of the multipart endpoint cost resource is
"multipart/related;type=application/alto-endpointcost+json".
7.2.2. HTTP Method
The multipart endpoint cost resource is requested using the HTTP POST
method.
7.2.3. Accept Input Parameters
The input parameters of the multipart endpoint cost resource are
supplied in the body of an HTTP POST request. This document extends
the input parameters to an endpoint cost map with a data format
indicated by the media type "application/alto-
endpointcostparams+json", which is a JSON object of type
PVEndpointCostParams, where
object {
[EntityPropertyName ane-property-names<0..*>;]
} PVReqEndpointcost : ReqEndpointcost;
with fields:
ane-property-names: This document defines the "ane-property-names"
in PVReqEndpointcost as the same as in PVReqFilteredCostMap. See
Section 7.1.3.
Example: Consider the network in Figure 1. If an ALTO client wants
to query the "max-reservable-bandwidth" between eh1 and eh2, it can
submit the following request.
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POST /ecs/pv HTTP/1.1
Host: alto.example.com
Accept: multipart/related;type=application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"endpoints": {
"srcs": [ "ipv4:1.2.3.4" ],
"dsts": [ "ipv4:2.3.4.5" ]
},
"ane-property-names": [ "max-reservable-bandwidth" ]
}
7.2.4. Capabilities
The capabilities of the multipart endpoint cost resource are defined
by a JSON object of type PVEndpointcostCapabilities, which is defined
as the same as PVFilteredCostMapCapabilities. See Section 7.1.4.
7.2.5. Uses
If this resource supports "persistent-entity-id", it MUST also
include the defining resources of persistent ANEs that may appear in
the response.
7.2.6. Response
The response MUST indicate an error, using ALTO protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is
invalid.
The "Content-Type" header of the response MUST be "multipart/related"
as defined by [RFC7285] with the following parameters:
type: The type parameter MUST be "application/alto-
endpointcost+json".
start: The start parameter is as defined in Section 7.1.6.
boundary: The boundary parameter is as defined in [RFC2387].
The body MUST consist of two parts:
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* The Path Vector part MUST include "Resource-Id" and "Content-Type"
in its header. The value of "Resource-Id" MUST has the format of
a Part Resource ID. The "Content-Type" MUST be "application/alto-
endpointcost+json".
The body of the Path Vector part MUST be a JSON object with the
same format as defined in Section 11.5.1.6 of [RFC7285]. The JSON
object MUST include the "vtag" field in the "meta" field, which
provides the version tag of the returned endpoint cost map. The
resource ID of the version tag MUST follow the format in
Section 5.3.2.
* The Unified Property Map part MUST also include "Resource-Id" and
"Content-Type" in its header. The value of "Resource-Id" MUST has
the format of a Part Resource ID. The "Content-Type" MUST be
"application/alto-propmap+json".
The body of the Unified Property Map part MUST be a JSON object
with the same format as defined in Section 4.6 of
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include
the "dependent-vtags" field in the "meta" field. The value of the
"dependent-vtags" field MUST be an array of VersionTag objects as
defined by Section 10.3 of [RFC7285]. The "vtag" of the Path
Vector part MUST be included in the "dependent-vtags". If
"persistent-entity-id" is requested, the version tags of the
dependent resources that MAY expose the entities in the response
MUST also be included. The PropertyMapData has one member for
each ANEName that appears in the Path Vector part, which is an
entity identifier belonging to the self-defined entity domain as
defined in Section 5.1.2.3 of [I-D.ietf-alto-unified-props-new].
The EntityProps has one member for each property requested by the
ALTO client if applicable.
If the "start" parameter is not present, the Path Vector part MUST be
the first part in the multipart response. If any part is NOT
present, the client MUST discard the received information and send
another request if necessary.
Example: Consider the network in Figure 1. The response of the
example request in Section 7.2.3 is as follows.
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HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: multipart/related; boundary=example-1;
type=application/alto-endpointcost+json
--example-1
Resource-Id: ecs
Content-Type: application/alto-endpointcost+json
{
"meta": {
"vtag": {
"resource-id": "ecs-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
},
"dependent-vtags": [
{
"resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f6228"
}
],
"cost-type": { "cost-mode": "array", "cost-metric": "ane-path" }
},
"cost-map": {
"ipv4:1.2.3.4": { "ipv4:2.3.4.5": ["ANE1"] }
}
}
--example-1
Resource-Id: propmap
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "ecs-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
}
]
},
"property-map": {
".ane:ANE1": { "max-reservable-bandwidth": 100000000 }
}
}
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8. Examples
This section lists some examples of Path Vector queries and the
corresponding responses. Some long lines are truncated for better
readability.
8.1. Example: Information Resource Directory
To give a comprehensive example of the Path Vector extension, we
consider the network in Figure 5. The example ALTO server provides
the following information resources:
* "my-default-networkmap": A Network Map resource which contains the
PIDs in the network.
* "filtered-cost-map-pv": A Multipart Filtered Cost Map resource for
Path Vector, which exposes the "max-reservable-bandwidth" property
for the PIDs in "my-default-networkmap".
* "ane-props": A filtered Unified Property resource that exposes the
information for persistent ANEs in the network.
* "endpoint-cost-pv": A Multipart Endpoint Cost Service for Path
Vector, which exposes the "max-reservable-bandwidth" and the
"persistent-entity-id" properties.
* "update-pv": An Update Stream service, which provides the
incremental update service for the "endpoint-cost-pv" service.
Below is the Information Resource Directory of the example ALTO
server. To enable the Path Vector extension, the "path-vector" cost
type (Section 6.5) is defined in the "cost-types" of the "meta"
field, and is included in the "cost-type-names" of resources
"filetered-cost-map-pv" and "endpoint-cost-pv".
{
"meta": {
"cost-types": {
"path-vector": {
"cost-mode": "array",
"cost-metric": "ane-path"
}
}
},
"resources": {
"my-default-networkmap": {
"uri" : "https://alto.example.com/networkmap",
"media-type" : "application/alto-networkmap+json"
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},
"filtered-cost-map-pv": {
"uri": "https://alto.example.com/costmap/pv",
"media-type": "multipart/related;
type=application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json",
"capabilities": {
"cost-type-names": [ "path-vector" ],
"ane-property-names": [ "max-reservable-bandwidth" ]
},
"uses": [ "my-default-networkmap" ]
},
"ane-props": {
"uri": "https://alto.example.com/ane-props",
"media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json",
"capabilities": {
"mappings": {
".ane": [ "cpu" ]
}
}
},
"endpoint-cost-pv": {
"uri": "https://alto.exmaple.com/endpointcost/pv",
"media-type": "multipart/related;
type=application/alto-endpointcost+json",
"accepts": "application/alto-endpointcostparams+json",
"capabilities": {
"cost-type-names": [ "path-vector" ],
"ane-property-names": [
"max-reservable-bandwidth", "persistent-entity-id"
]
},
"uses": [ "ane-props" ]
},
"update-pv": {
"uri": "https://alto.example.com/updates/pv",
"media-type": "text/event-stream",
"uses": [ "endpoint-cost-pv" ],
"accepts": "application/alto-updatestreamparams+json",
"capabilities": {
"support-stream-control": true
}
}
}
}
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8.2. Example: Multipart Filtered Cost Map
The following examples demonstrate the request to the "filtered-cost-
map-pv" resource and the corresponding response.
The request uses the "path-vector" cost type in the "cost-type"
field. The "ane-property-names" field is missing, indicating that
the client only requests for the Path Vector but not the ANE
properties.
The response consists of two parts. The first part returns the array
of ANEName for each source and destination pair. There are two ANEs,
where "L1" represents the interconnection link L1, and "L2"
represents the interconnection link L2.
The second part returns an empty Property Map. Note that the ANE
entries are omitted since they have no properties (See Section 3.1 of
[I-D.ietf-alto-unified-props-new]).
POST /costmap/pv HTTP/1.1
Host: alto.example.com
Accept: multipart/related;type=application/alto-costmap+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-costmapfilter+json
{
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"pids": {
"srcs": [ "PID1" ],
"dsts": [ "PID3", "PID4" ]
}
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: multipart/related; boundary=example-1;
type=application/alto-costmap+json
--example-1
Resource-Id: costmap
Content-Type: application/alto-costmap+json
{
"meta": {
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"vtag": {
"resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
},
"dependent-vtags": [
{
"resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f6228"
}
],
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
}
},
"cost-map": {
"PID1": {
"PID3": [ "L1" ],
"PID4": [ "L1", "L2" ]
}
}
}
--example-1
Resource-Id: propmap
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "filtered-cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
}
]
},
"property-map": {
}
}
8.3. Example: Multipart Endpoint Cost Resource
The following examples demonstrate the request to the "endpoint-cost-
pv" resource and the corresponding response.
The request uses the path vector cost type in the "cost-type" field,
and queries the Maximum Reservable Bandwidth ANE property and the
Persistent Entity property.
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The response consists of two parts. The first part returns the array
of ANEName for each valid source and destination pair, where "NET1"
represent sub-network NET1, and "AGGR" is the aggregation of L1 and
NET3.
The second part returns the requested properties of ANEs. Since NET1
has sufficient bandwidth, it sets the "max-reservable-bandwidth" to a
sufficiently large number. It also represents a persistent ANE
defined in the "ane-props" resource, identified by "ane-
props.ane:datacenter1". The aggregated "max-reservable-bandwidth" of
ane:AGGR is constrained by the link capacity of L1. The "persistent-
entity-id" property is omitted as both L1 and NET3 do not represent
any persistent entity.
POST /endpointcost/pv HTTP/1.1
Host: alto.example.com
Accept: multipart/related;
type=application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
},
"endpoints": {
"srcs": [ "ipv4:1.2.3.4", "ipv4:2.3.4.5" ],
"dsts": [ "ipv4:3.4.5.6" ]
},
"ane-property-names": [
"max-reservable-bandwidth",
"persistent-entity-id"
]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: multipart/related; boundary=example-2;
type=application/alto-endpointcost+json
--example-2
Resource-Id: ecs
Content-Type: application/alto-endpointcost+json
{
"meta": {
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"vtags": {
"resource-id": "endpoint-cost-pv.ecs",
"tag": "bb6bb72eafe8f9bdc4f335c7ed3b10822a391cef"
},
"cost-type": {
"cost-mode": "array",
"cost-metric": "ane-path"
}
},
"endpoint-cost-map": {
"ipv4:1.2.3.4": {
"ipv4:3.4.5.6": [ "NET1", "AGGR" ]
},
"ipv4:2.3.4.5": {
"ipv4:3.4.5.6": [ "NET1", "AGGR" ]
}
}
}
--example-2
Resource-Id: propmap
Content-Type: application/alto-propmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "endpoint-cost-pv.ecs",
"tag": "bb6bb72eafe8f9bdc4f335c7ed3b10822a391cef"
},
{
"resource-id": "ane-props",
"tag": "bf3c8c1819d2421c9a95a9d02af557a3"
}
]
},
"property-map": {
".ane:NET1": {
"max-reservable-bandwidth": 50000000000,
"persistent-entity-id": "ane-props.ane:datacenter1",
},
".ane:AGGR": {
"max-reservable-bandwidth": 10000000000
}
}
}
After the client obtains "ane-props.ane:datacenter1", it can query
the "ane-props" resource to get the properties of the persistent ANE.
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8.4. Example: Incremental Updates
In this example, an ALTO client subscribes to the incremental update
for the multipart endpoint cost resource "endpoint-cost-pv".
POST /updates/pv HTTP/1.1
Host: alto.example.com
Accept: text/event-stream
Content-Type: application/alto-updatestreamparams+json
Content-Length: [TBD]
{
"add": {
"ecspvsub1": {
"resource-id": "endpoint-cost-pv",
"input": <ecs-input>
}
}
}
Based on the server-side process defined in
[I-D.ietf-alto-incr-update-sse], the ALTO server will send the
"control-uri" first using Server-Sent Event (SSE), followed by the
full response of the multipart message.
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: text/event-stream
event: application/alto-updatestreamcontrol+json
data: {"control-uri": "https://alto.example.com/updates/streams/123"}
event: multipart/related;boundary=example-3;
type=application/alto-endpointcost+json,ecspvsub1
data: --example-3
data: Resource-ID: ecsmap
data: Content-Type: application/alto-endpointcost+json
data:
data: <endpoint-cost-map-entry>
data: --example-3
data: Resource-ID: propmap
data: Content-Type: application/alto-propmap+json
data:
data: <property-map-entry>
data: --example-3--
When the contents change, the ALTO server will publish the updates
for each node in this tree separately.
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event: application/merge-patch+json, ecspvsub1.ecsmap
data: <Merge patch for endpoint-cost-map-update>
event: application/merge-patch+json, ecspvsub1.propmap
data: <Merge patch for property-map-update>
9. Compatibility
9.1. Compatibility with Legacy ALTO Clients/Servers
The multipart filtered cost map resource and the multipart endpoint
cost resource has no backward compatibility issue with legacy ALTO
clients and servers. Although these two types of resources reuse the
media types defined in the base ALTO protocol for the accept input
parameters, they have different media types for responses. If the
ALTO server provides these two types of resources, but the ALTO
client does not support them, the ALTO client will ignore the
resources without conducting any incompatibility.
9.2. Compatibility with Multi-Cost Extension
This document does not specify how to integrate the Path Vector cost
type with the multi-cost extension [RFC8189]. While it is not
RECOMMENDED to put the Path Vector cost type with other cost types in
a single query, there is no compatibility issue.
9.3. Compatibility with Incremental Update
The extension specified in this document is NOT compatible with the
original incremental update extension
[I-D.ietf-alto-incr-update-sse]. A legacy ALTO client CANNOT
recognize the compound client-id, and a legacy ALTO server MAY use
the same client-id for updates of both parts.
ALTO clients and servers MUST follow the specifications given in this
document to support incremental updates for a Path Vector resource.
9.4. Compatibility with Cost Calendar
The extension specified in this document is compatible with the Cost
Calendar extension [I-D.ietf-alto-cost-calendar]. When used together
with the Cost Calendar extension, the cost value between a source and
a destination is an array of path vectors, where the k-th path vector
refers to the abstract network paths traversed in the k-th time
interval by traffic from the source to the destination.
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When used with time-varying properties, e.g., maximum reservable
bandwidth (maxresbw), a property of a single ANE may also have
different values in different time intervals. In this case, if such
an ANE has different property values in two time intervals, it MUST
be treated as two different ANEs, i.e., with different entity
identifiers. However, if it has the same property values in two time
intervals, it MAY use the same identifier.
This rule allows the Path Vector extension to represent both changes
of ANEs and changes of the ANEs' properties in a uniform way. The
Path Vector part is calendared in a compatible way, and the Property
Map part is not affected by the calendar extension.
The two extensions combined together can provide the historical
network correlation information for a set of source and destination
pairs. A network broker or client may use this information to derive
other resource requirements such as Time-Block-Maximum Bandwidth,
Bandwidth-Sliding-Window, and Time-Bandwidth-Product (TBP) (See
[SENSE] for details).
10. General Discussions
10.1. Constraint Tests for General Cost Types
The constraint test is a simple approach to query the data. It
allows users to filter the query result by specifying some boolean
tests. This approach is already used in the ALTO protocol.
[RFC7285] and [RFC8189] allow ALTO clients to specify the
"constraints" and "or-constraints" tests to better filter the result.
However, the current syntax can only be used to test scalar cost
types, and cannot easily express constraints on complex cost types,
e.g., the Path Vector cost type defined in this document.
In practice, developing a language for general-purpose boolean tests
can be complex and is likely to be a duplicated work. Thus, it is
worth looking into the direction of integrating existing well-
developed query languages, e.g., XQuery and JSONiq, or their subset
with ALTO.
Filtering the Path Vector results or developing a more sophisticated
filtering mechanism is beyond the scope of this document.
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10.2. General Multipart Resources Query
Querying multiple ALTO information resources continuously MAY be a
general requirement. And the coming issues like inefficiency and
inconsistency are also general. There is no standard solving these
issues yet. So we need some approach to make the ALTO client request
the compound ALTO information resources in a single query.
11. Security Considerations
This document is an extension of the base ALTO protocol, so the
Security Considerations [RFC7285] of the base ALTO protocol fully
apply when this extension is provided by an ALTO server.
The Path Vector extension requires additional considerations on two
security considerations discussed in the base protocol:
confidentiality of ALTO information (Section 15.3 of [RFC7285]) and
availability of ALTO service (Section 15.5 of [RFC7285]).
For confidentiality of ALTO information, a network operator should be
aware of that this extension may introduce a new risk: the Path
Vector information may make network attacks easier. For example, as
the Path Vector information may reveal more fine-grained internal
network structures than the base protocol, an ALTO client may detect
the bottleneck link and start a distributed denial-of-service (DDoS)
attack involving minimal flows to conduct the in-network congestion.
To mitigate this risk, the ALTO server should consider protection
mechanisms to reduce information exposure or obfuscate the real
information, in particular, in settings where the network and the
application do not belong to the same trust domain. But the
implementation of Path Vector extension involving reduction or
obfuscation should guarantee the requested properties are still
accurate, for example, by using minimal feasible region compression
algorithms [TON2019] or obfuscation protocols [SC2018][JSAC2019].
For availability of ALTO service, an ALTO server should be cognizant
that using Path Vector extension might have a new risk: frequent
requesting for Path Vectors might conduct intolerable increment of
the server-side storage and break the ALTO server, for example, if an
ALTO server implementation dynamically computes the Path Vectors for
each requests. Hence, the service providing Path Vectors may become
an entry point for denial-of-service attacks on the availability of
an ALTO server. To avoid this risk, authenticity and authorization
of this ALTO service may need to be better protected. Also, an ALTO
server may consider using optimizations such as precomputation-and-
projection mechanisms [JSAC2019].
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12. IANA Considerations
12.1. ALTO Entity Domain Type Registry
This document registers a new entry to the ALTO Domain Entity Type
Registry, as instructed by Section 12.2 of
[I-D.ietf-alto-unified-props-new]. The new entry is as shown below
in Table 1.
+============+=========================+=========================+
| Identifier | Entity Address Encoding | Hierarchy & Inheritance |
+============+=========================+=========================+
| ane | See Section 6.2.2 | None |
+------------+-------------------------+-------------------------+
Table 1: ALTO Entity Domain Type Registry
Identifier: See Section 6.2.1.
Entity Identifier Encoding: See Section 6.2.2.
Hierarchy: None
Inheritance: None
Media Type of Defining Resource: See Section 6.2.4.
Security Considerations: In some usage scenarios, ANE addresses
carried in ALTO Protocol messages may reveal information about an
ALTO client or an ALTO service provider. Applications and ALTO
service providers using addresses of ANEs will be made aware of
how (or if) the addressing scheme relates to private information
and network proximity, in further iterations of this document.
12.2. ALTO Entity Property Type Registry
Two initial entries are registered to the ALTO Domain "ane" in the
"ALTO Entity Property Type Registry", as instructed by Section 12.3
of [I-D.ietf-alto-unified-props-new]. The two new entries are shown
below in Table 2.
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+==========================+====================+
| Identifier | Intended Semantics |
+==========================+====================+
| max-reservable-bandwidth | See Section 6.4.1 |
+--------------------------+--------------------+
| persistent-entity-id | See Section 6.4.2 |
+--------------------------+--------------------+
Table 2: Initial Entries for ane Domain in
the ALTO Entity Property Types Registry
13. Acknowledgments
The authors would like to thank discussions with Andreas Voellmy,
Erran Li, Haibin Song, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan
Liu, Xiao Shi, Xin Wang, and Yan Luo. The authors thank Greg
Bernstein (Grotto Networks), Dawn Chen (Tongji University), Wendy
Roome, and Michael Scharf for their contributions to earlier drafts.
14. References
14.1. Normative References
[I-D.ietf-alto-cost-calendar]
Randriamasy, S., Yang, Y., WU, Q., Lingli, D., and N.
Schwan, "Application-Layer Traffic Optimization (ALTO)
Cost Calendar", Work in Progress, Internet-Draft, draft-
ietf-alto-cost-calendar-21, 17 March 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-cost-
calendar-21.txt>.
[I-D.ietf-alto-incr-update-sse]
Roome, W. and Y. Yang, "ALTO Incremental Updates Using
Server-Sent Events (SSE)", Work in Progress, Internet-
Draft, draft-ietf-alto-incr-update-sse-22, 20 March 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-alto-incr-
update-sse-22.txt>.
[I-D.ietf-alto-unified-props-new]
Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K.
Gao, "Unified properties for the ALTO protocol", Work in
Progress, Internet-Draft, draft-ietf-alto-unified-props-
new-14, 17 November 2020, <http://www.ietf.org/internet-
drafts/draft-ietf-alto-unified-props-new-14.txt>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2216] Shenker, S. and J. Wroclawski, "Network Element Service
Specification Template", RFC 2216, DOI 10.17487/RFC2216,
September 1997, <https://www.rfc-editor.org/info/rfc2216>.
[RFC2387] Levinson, E., "The MIME Multipart/Related Content-type",
RFC 2387, DOI 10.17487/RFC2387, August 1998,
<https://www.rfc-editor.org/info/rfc2387>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
Application-Layer Traffic Optimization (ALTO)", RFC 8189,
DOI 10.17487/RFC8189, October 2017,
<https://www.rfc-editor.org/info/rfc8189>.
14.2. Informative References
[AAAI2019] Xiang, Q., Yu, H., Aspnes, J., Le, F., Kong, L., and Y.R.
Yang, "Optimizing in the dark: Learning an optimal
solution through a simple request interface", Proceedings
of the AAAI Conference on Artificial Intelligence 33,
1674-1681 , 2019.
[I-D.contreras-alto-service-edge]
Contreras, L., Perez, D., and C. Rothenberg, "Use of ALTO
for Determining Service Edge", Work in Progress, Internet-
Draft, draft-contreras-alto-service-edge-02, 2 November
2020, <http://www.ietf.org/internet-drafts/draft-
contreras-alto-service-edge-02.txt>.
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[I-D.huang-alto-mowie-for-network-aware-app]
Huang, W., Zhang, Y., Yang, R., Xiong, C., Lei, Y., Han,
Y., and G. Li, "MoWIE for Network Aware Application", Work
in Progress, Internet-Draft, draft-huang-alto-mowie-for-
network-aware-app-01, 13 July 2020, <http://www.ietf.org/
internet-drafts/draft-huang-alto-mowie-for-network-aware-
app-01.txt>.
[I-D.ietf-alto-performance-metrics]
WU, Q., Yang, Y., Lee, Y., Dhody, D., Randriamasy, S., and
L. Contreras, "ALTO Performance Cost Metrics", Work in
Progress, Internet-Draft, draft-ietf-alto-performance-
metrics-12, 13 July 2020, <http://www.ietf.org/internet-
drafts/draft-ietf-alto-performance-metrics-12.txt>.
[I-D.ietf-dmm-5g-uplane-analysis]
Homma, S., Miyasaka, T., Matsushima, S., and D. Voyer,
"User Plane Protocol and Architectural Analysis on 3GPP 5G
System", Work in Progress, Internet-Draft, draft-ietf-dmm-
5g-uplane-analysis-04, 2 November 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-dmm-5g-
uplane-analysis-04.txt>.
[I-D.yang-alto-deliver-functions-over-networks]
Yang, S., Cui, L., Xu, M., Yang, Y., and R. Huang,
"Delivering Functions over Networks: Traffic and
Performance Optimization for Edge Computing using ALTO",
Work in Progress, Internet-Draft, draft-yang-alto-deliver-
functions-over-networks-01, 13 July 2020,
<http://www.ietf.org/internet-drafts/draft-yang-alto-
deliver-functions-over-networks-01.txt>.
[JSAC2019] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F.,
MacAuley, J., Newman, H., and Y.R. Yang, "Toward Fine-
Grained, Privacy-Preserving, Efficient Multi-Domain
Network Resource Discovery", IEEE/ACM IEEE Journal on
Selected Areas of Communication 37(8): 1924-1940, 2019.
[LHC] "CERN - LHC", 2019, <https://atlas.cern/tags/lhc>.
[SC2018] Xiang, Q., Zhang, J., Wang, X., Liu, Y., Guok, C., Le, F.,
MacAuley, J., Newman, H., and Y.R. Yang, "Fine-grained,
multi-domain network resource abstraction as a fundamental
primitive to enable high-performance, collaborative data
sciences", Proceedings of the Super Computing 2018,
5:1-5:13 , 2019.
[SENSE] "Services - SENSE", 2019, <http://sense.es.net/services>.
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[TON2019] Gao, K., Xiang, Q., Wang, X., Yang, Y.R., and J. Bi, "An
objective-driven on-demand network abstraction for
adaptive applications", IEEE/ACM Transactions on
Networking (TON) Vol 27, no. 2 (2019): 805-818., 2019.
Appendix A. Changes since -12
Revision -13
* changes the abstract based on the chairs' reviews
* integrates Richard's responds to WGLC reviews
Appendix B. Changes since -11
Revision -12
* clarifies the definition of ANEs in a similar way as how Network
Elements is defined in [RFC2216]
* restructures several paragraphs that are not clear (Sec 3, Path
Vector bullet, Sec 4.2, Sec 5.1.3, Sec 6.2.4, Sec 6.4.2, Sec 9.3)
* uses "ALTO Entity Domain Type Registry"
Appendix C. Changes since -10
Revision -11
* replaces "part" with "components" in the abstract;
* identifies additional requirements (AR) derived from the flow
scheduling example, and introduces how the extension addresses the
additional requirements
* fixes the inconsistent use of "start" parameter in multipart
responses;
* specifies explicitly how to handle "cost-constraints";
* uses the latest IANA registration mechanism defined in
[I-D.ietf-alto-unified-props-new];
* renames "persistent-entities" to "persistent-entity-id";
* makes "application/alto-propmap+json" as the media type of
defining resources for the "ane" domain;
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* updates the examples;
* adds the discussion on ephemeral and persistent ANEs.
Appendix D. Changes since -09
Revision -10
* revises the introduction which
- extends the scope where the PV extension can be applied beyond
the "path correlation" information
* brings back the capacity region use case to better illustrate the
problem
* revises the overview to explain and defend the concepts and
decision choices
* fixes inconsistent terms, typos
Appendix E. Changes since -08
This revision
* fixes a few spelling errors
* emphasizes that abstract network elements can be generated on
demand in both introduction and motivating use cases
Appendix F. Changes Since Version -06
* We emphasize the importance of the path vector extension in two
aspects:
1. It expands the problem space that can be solved by ALTO, from
preferences of network paths to correlations of network paths.
2. It is motivated by new usage scenarios from both application's
and network's perspectives.
* More use cases are included, in addition to the original capacity
region use case.
* We add more discussions to fully explore the design space of the
path vector extension and justify our design decisions, including
the concept of abstract network element, cost type (reverted to
-05), newer capabilities and the multipart message.
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* Fix the incremental update process to be compatible with SSE -16
draft, which uses client-id instead of resource-id to demultiplex
updates.
* Register an additional ANE property (i.e., persistent-entities) to
cover all use cases mentioned in the draft.
Authors' Addresses
Kai Gao
Sichuan University
No.24 South Section 1, Yihuan Road
Chengdu
610000
China
Email: kaigao@scu.edu.cn
Young Lee
Samsung
South Korea
Email: younglee.tx@gmail.com
Sabine Randriamasy
Nokia Bell Labs
Route de Villejust
91460 Nozay
France
Email: sabine.randriamasy@nokia-bell-labs.com
Yang Richard Yang
Yale University
51 Prospect Street
New Haven, CT
United States of America
Email: yry@cs.yale.edu
Jingxuan Jensen Zhang
Tongji University
4800 Caoan Road
Shanghai
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201804
China
Email: jingxuan.n.zhang@gmail.com
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