draft-ietf-alto-path-vector-03.txt   draft-ietf-alto-path-vector-04.txt 
ALTO WG G. Bernstein ALTO WG G. Bernstein
Internet-Draft Grotto Networking Internet-Draft Grotto Networking
Intended status: Standards Track S. Chen Intended status: Standards Track S. Chen
Expires: September 6, 2018 Tongji University Expires: January 3, 2019 Tongji University
K. Gao K. Gao
Tsinghua University Tsinghua University
Y. Lee Y. Lee
Huawei Huawei
W. Roome W. Roome
M. Scharf M. Scharf
Nokia Nokia
Y. Yang Y. Yang
Yale University Yale University
J. Zhang J. Zhang
Tongji University Tongji University
March 5, 2018 July 2, 2018
ALTO Extension: Path Vector Cost Type ALTO Extension: Path Vector Cost Type
draft-ietf-alto-path-vector-03.txt draft-ietf-alto-path-vector-04
Abstract Abstract
The Application-Layer Traffic Optimization (ALTO) protocol [RFC7285] The Application-Layer Traffic Optimization (ALTO) protocol [RFC7285]
has defined several resources and services to provide clients with has defined cost maps and endpoint cost maps to provide basic network
basic network information. However, the base ALTO protocol and information. However, they provide only scalar (numerical or
latest extensions only provide end-to-end metrics, which are ordinal) cost mode values, which are insufficient to satisfy the
insufficient to satisfy the demands of solving more complex network demands of solving more complex network optimization problems. This
optimization problems. This document introduces an extension to the document introduces an extension to the base ALTO protocol, namely
base ALTO protocol, namely the path-vector extension, which allows the path-vector extension, which allows ALTO clients to query
ALTO clients to query information such as capacity regions for a information such as capacity regions for a given set of flows. A
given set of flows. A non-normative example called multi-flow non-normative example called multi-flow scheduling is presented to
scheduling is presented to illustrate the limitations of existing illustrate the limitations of existing ALTO endpoint cost maps.
ALTO (endpoint) cost maps. After that, details of the extension are After that, details of the extension are defined.
defined.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on September 6, 2018. This Internet-Draft will expire on January 3, 2019.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Use Case: Capacity Region for Multi-Flow Scheduling . . . . . 5 3. Use Case: Capacity Region for Multi-Flow Scheduling . . . . . 5
4. Overview of Path Vector Extensions . . . . . . . . . . . . . 7 4. Overview of Path Vector Extensions . . . . . . . . . . . . . 7
4.1. New Cost Type to Encode Path Vectors . . . . . . . . . . 7 4.1. New Cost Type to Encode Path Vectors . . . . . . . . . . 7
4.2. New Entity Domain to Provide ANE Properties . . . . . . . 8 4.2. New ALTO Entity Domain to Provide ANE Properties . . . . 8
4.3. New Service to Enable Multipart Resources . . . . . . . . 8 4.3. Extended Cost Map/Endpoint Cost Service for Compound
5. Path Vector Extension: Basic Data Types . . . . . . . . . . . 9 Resources . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . 9 5. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1.1. Cost Mode: array . . . . . . . . . . . . . . . . . . 9 5.1. Cost Mode: array . . . . . . . . . . . . . . . . . . . . 9
5.1.2. Cost Metric: ane-path . . . . . . . . . . . . . . . . 9 5.2. Cost Metric: ane-path . . . . . . . . . . . . . . . . . . 9
5.1.3. Path Vector Cost Type Semantics . . . . . . . . . . . 9 5.3. Path Vector Cost Type Semantics . . . . . . . . . . . . . 9
5.2. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . 10 6. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2.1. Domain Name . . . . . . . . . . . . . . . . . . . . . 10 6.1. Domain Name . . . . . . . . . . . . . . . . . . . . . . . 10
5.2.2. Domain-Specific Entity Addresses . . . . . . . . . . 10 6.2. Domain-Specific Entity Addresses . . . . . . . . . . . . 10
5.2.3. Hierarchy and Inheritance . . . . . . . . . . . . . . 11 6.3. Hierarchy and Inheritance . . . . . . . . . . . . . . . . 10
5.3. Abstract Network Element Name . . . . . . . . . . . . . . 11 7. Protocol Extensions for Path Vector Compound Query . . . . . 10
6. Path Vector Extension: Services . . . . . . . . . . . . . . . 11 7.1. Filtered Cost Map Extensions . . . . . . . . . . . . . . 11
6.1. Filtered Cost Map Extensions . . . . . . . . . . . . . . 11 7.1.1. Capabilities . . . . . . . . . . . . . . . . . . . . 11
6.1.1. Capabilities . . . . . . . . . . . . . . . . . . . . 11 7.1.2. Accept Input Parameters . . . . . . . . . . . . . . . 12
6.1.2. Accept Input Parameters . . . . . . . . . . . . . . . 12 7.1.3. Response . . . . . . . . . . . . . . . . . . . . . . 12
6.1.3. Response . . . . . . . . . . . . . . . . . . . . . . 12
6.2. Endpoint Cost Service Extensions . . . . . . . . . . . . 12 7.2. Endpoint Cost Service Extensions . . . . . . . . . . . . 12
6.2.1. Capabilities . . . . . . . . . . . . . . . . . . . . 12 7.2.1. Capabilities . . . . . . . . . . . . . . . . . . . . 13
6.2.2. Accept Input Parameters . . . . . . . . . . . . . . . 12 7.2.2. Accept Input Parameters . . . . . . . . . . . . . . . 13
6.2.3. Response . . . . . . . . . . . . . . . . . . . . . . 13 7.2.3. Response . . . . . . . . . . . . . . . . . . . . . . 13
6.3. Multipart Cost Property Service . . . . . . . . . . . . . 13 8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.3.1. Media Type . . . . . . . . . . . . . . . . . . . . . 13 8.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 13
6.3.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 13 8.2. Information Resource Directory Example . . . . . . . . . 14
6.3.3. Accept Input Parameters . . . . . . . . . . . . . . . 13 8.3. Example # 1 . . . . . . . . . . . . . . . . . . . . . . . 16
6.3.4. Capabilities . . . . . . . . . . . . . . . . . . . . 14 8.4. Example # 2 . . . . . . . . . . . . . . . . . . . . . . . 18
6.3.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 14 8.5. Example #3 . . . . . . . . . . . . . . . . . . . . . . . 20
6.3.6. Response . . . . . . . . . . . . . . . . . . . . . . 14 9. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 22
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 22
7.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 15 9.2. Compatibility with Multi-Cost Extension . . . . . . . . . 23
7.2. Information Resource Directory Example . . . . . . . . . 15 9.3. Compatibility with Incremental Update . . . . . . . . . . 23
7.3. Example # 1 . . . . . . . . . . . . . . . . . . . . . . . 17 10. General Discussions . . . . . . . . . . . . . . . . . . . . . 23
7.4. Example # 2 . . . . . . . . . . . . . . . . . . . . . . . 18 10.1. Provide Calendar for Property Map . . . . . . . . . . . 23
8. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 19 10.2. Constraint Tests for General Cost Types . . . . . . . . 24
8.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 19 10.3. General Compound Resources Query . . . . . . . . . . . . 24
8.2. Compatibility with Multi-Cost Extensions . . . . . . . . 20 11. Security Considerations . . . . . . . . . . . . . . . . . . . 24
8.3. Compatibility with Incremental Update . . . . . . . . . . 20 11.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 24
9. Design Decisions and Discussions . . . . . . . . . . . . . . 20 11.2. Resource Consumption on ALTO Servers . . . . . . . . . . 25
9.1. Provide More General Calendar Extension . . . . . . . . . 20 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
10. Security Considerations . . . . . . . . . . . . . . . . . . . 21 12.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 25
10.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 21 12.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 25
10.2. Resource Consumption on ALTO Servers . . . . . . . . . . 21 12.3. ALTO Domain Registry . . . . . . . . . . . . . . . . . . 25
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 12.4. ALTO Network Element Property Type Registry . . . . . . 26
11.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 21 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
11.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 22 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
11.3. ALTO Entity Domain Registry . . . . . . . . . . . . . . 22 14.1. Normative References . . . . . . . . . . . . . . . . . . 26
11.4. ALTO Network Element Property Type Registry . . . . . . 22 14.2. Informative References . . . . . . . . . . . . . . . . . 26
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
13.1. Normative References . . . . . . . . . . . . . . . . . . 23
13.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
The base ALTO protocol [RFC7285] is designed to expose network The base ALTO protocol [RFC7285] is designed to expose network
information through services such as Cost Map and Endpoint Cost information through services such as cost map and endpoint cost
service. These services use an extreme "single-node" network view service. These services use an extreme "single-node" network view
abstraction, which represents the whole network with a single node abstraction, which represents the whole network with a single node
and hosts with "endpoint groups" directly connected to the node. and hosts with "endpoint groups" directly connected to the node.
Although the "single-node" network view abstraction works well in Although the "single-node" network view abstraction works well in
many settings, it lacks the ability to support emerging use cases, many settings, it lacks the ability to support emerging use cases,
such as inter-datacenter data transfers such as applications requiring large bandwidth or latency sensitivity
[I-D.bernstein-alto-topo], and inter-datacenter data transfers
[I-D.lee-alto-app-net-info-exchange]. For these use cases, [I-D.lee-alto-app-net-info-exchange]. For these use cases,
applications require a more powerful network view abstraction beyond applications require a more powerful network view abstraction beyond
the "single-node" abstraction to support application capabilities, in the "single-node" abstraction to support application capabilities, in
particular, the ability of multi-flow scheduling. particular, the ability multi-flow scheduling.
To support capabilities like multi-flow scheduling, To support capabilities like multi-flow scheduling, this document
[I-D.yang-alto-topology] provides many candidate network view uses a "path vector" abstraction to represent more detailed network
abstractions. This document uses one of those abstractions called graph information like capacity regions. The path vector abstraction
"path vector" abstraction. The path vector abstraction use path uses path vectors with abstract network elements to provide network
vectors with abstract network elements to provide network graph view graph view for applications. A path vector consists of a sequence of
for applications. Here, abstract network elements can be links, Abstract Network Elements (ANEs) that end-to-end traffic goes
switches, middleboxes and their aggregations. And a path vector through. ANEs can be links, switches, middleboxes, their
presents a sequence of abstract network elements that end-to-end aggregations, etc.; they have properties like "bandwidth", "delay",
traffic goes through. Each abstract network element can own several etc. These information may help the application avoid network
properties like "bandwidth" and "delay". These information may help congestion and achieve better application performance.
the application avoid network congestion, achieving better
application performance.
Providing path vector abstraction using ALTO introduces the following Providing path vector abstraction using ALTO introduces the following
requirements: additional requirements (ARs):
o Encoding path vectors rather than scalar cost values in cost maps: AR-1: The ALTO protocol SHOULD include the support for encoding
Cost maps allow only scalar (numerical or ordinal) cost values, array-like cost values rather than scalar cost values in cost maps
they cannot carry an array of abstract network elements as a cost. or endpoint cost maps.
A new cost type is required to encode path vectors as costs in
cost maps.
o Encoding the properties of abstract network elements: Unified The ALTO server providing path vector abstraction SHOULD convey
property map can provide properties of endpoints and pids, but it sequences of ANEs between sources and destinations the ALTO client
cannot convey the properties of abstract network elements. A new requests. Theses information cannot be encoded by the scalar
entity domain needs to be registered so that unified property map types (numerical or ordinal) which the base ALTO protocol
can encode the properties of abstract network elements. supports. A new cost type is required to encode path vectors as
costs.
o Encapsulating multiple map messages in a single session: Making AR-2: The ALTO protocol SHOULD include the support for encoding
multiple queries to get path vectors and the properties of properties of ANEs.
abstract network elements introduce additional communication
overhead. A mechanism to provide multiple map messages in a Only the sequences of ANEs are not enough for most use cases
single session is necessary. mentioned previously. The properties of ANEs like "bandwidth" and
"delay" are required by applications to build the capacity region
or realize the latency sensitivity.
AR-3: The ALTO server SHOULD allow the ALTO client to query path
vectors and the properties of abstract network elements
consistently.
Path vectors and the properties of abstract network elements are
correlated information, but can be separated into different ALTO
information resources. A mechanism to query both of them
consistently is necessary.
This document proposes the path vector extension which satisfies This document proposes the path vector extension which satisfies
these additional requirements to the ALTO protocol. Specifically, it these additional requirements to the ALTO protocol. Specifically,
encodes selected abstract network elements in an end-to-end path with the ALTO protocol encodes the array of ANEs over an end-to-end path
a new cost type called "path-vector", and conveys the properties of using a new cost type, and conveys the properties of ANEs using
abstract network elements using unified property map. unified property map [I-D.ietf-alto-unified-props-new]. We also
provide an optional solution to query separated path vectors and
properties of ANEs in a consistent way. But querying general
separated resources consistently is not the scope in this document.
The rest of this document is organized as follows. Section 3 gives The rest of this document is organized as follows. Section 3 gives
an example of multi-flow scheduling and illustrates the limitations an example of multi-flow scheduling and illustrates the limitations
of the base ALTO protocol in such a use case. Section 4 gives an of the base ALTO protocol in such a use case. Section 4 gives an
overview of the path vector extension. Section 5 and Section 6 overview of the path vector extension. Section 5 introduces a new
define the formal extension. Section 7 presents several examples. cost type. Section 6 registers a new domain in Domain Registry.
Section 8 and Section 9 discusses compatibility issues with other Section 7 extends Filtered Cost Map and Endpoint Cost Service to
existing ALTO extensions and design decisions. Section 10 and support the compound resource query. Section 8 presents several
Section 11 review the security and IANA considerations. examples. Section 9 and Section 10 discusses compatibility issues
with other existing ALTO extensions and design decisions. Section 11
and Section 12 review the security and IANA considerations.
2. Terminology 2. Terminology
Besides the terms defined in [RFC7285], [RFC8189] and Besides the terms defined in [RFC7285] and
[I-D.ietf-alto-unified-props-new], this document also uses the [I-D.ietf-alto-unified-props-new], this document also uses the
following additional terms: Abstract Network Element, Abstract following additional terms: Abstract Network Element, Path Vector.
Network Element Name, Abstract Network Element Property, Abstract
Network Element Property Map, Path Vector and Path-Vector.
o Abstract Network Element (ANE): An abstract network element is an o Abstract Network Element (ANE): An abstract network element is an
abstraction of network components, it can be an aggregation of abstraction of network components; it can be an aggregation of
links, middle boxes, virtualized network function (VNF), or even a links, middle boxes, virtualized network function (VNF), etc. An
sub-network. An abstract network element has two attributes: a abstract network element has two types of attributes: a name and a
name and a set of properties. set of properties.
o Abstract Network Element Name (ANE Name): An abstract network
element name is an identifier that uniquely identifies an abstract
network element, as defined in Section 5.3.
o Abstract Network Element Property (ANE Property): An abstract
network element property is a network-related property of an
abstract network element. It can be "bandwidth" for links and
"delay" between two switches.
o Abstract Network Element Property Map (ANE Property Map): An
abstract network element property map is a Filtered Property Map
defined in [I-D.ietf-alto-unified-props-new] which supports the
"ane" domain in its "domain-types" capability.
o Path Vector: A path vector is an array of ALTO Abstract Network o Path Vector: A path vector is an array of ANEs. It presents an
Elements (ANEs). It presents an abstract network path between abstract network path between source/destination points such as
entities such as PIDs or endpoints. An ANE represents a selected PIDs or endpoints.
part of an end-to-end path that the ALTO Server considers worth
exposing.
3. Use Case: Capacity Region for Multi-Flow Scheduling 3. Use Case: Capacity Region for Multi-Flow Scheduling
Assume that an application has control over a set of flows, some Assume that an application has control over a set of flows, which may
flows may go through shared links or switches and share a bottleneck. go through shared links or switches and share a bottleneck. The
Existing cost maps can not reveal such information. 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 Specifically, consider a network as shown in Figure 1. The network
has 7 switches (sw1 to sw7) forming a dumb-bell topology. Switches 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 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 other side, and sw5-sw7 form the backbone. Endhosts eh1 to eh4 are
connected to access switches sw1 to sw4 respectively. Assume that connected to access switches sw1 to sw4 respectively. Assume that
the bandwidth of link eh1 -> sw1 and link sw1 -> sw5 are 150 Mbps, the bandwidth of link eh1 -> sw1 and link sw1 -> sw5 are 150 Mbps,
and the bandwidth of the rest links are 100 Mbps. and the bandwidth of the rest links are 100 Mbps.
+------+ +------+
skipping to change at page 6, line 50 skipping to change at page 6, line 42
+------+ +------+ +------+ +------+
| | | |
+----------------------+ +----------------------+
Figure 2: Base Single-Node Topology Abstraction. Figure 2: Base Single-Node Topology Abstraction.
Consider an application overlay (e.g., a large data analysis system) Consider an application overlay (e.g., a large data analysis system)
which wants to schedule the traffic among a set of end host source- which wants to schedule the traffic among a set of end host source-
destination pairs, say eh1 -> eh2 and eh1 -> eh4. The application destination pairs, say eh1 -> eh2 and eh1 -> eh4. The application
can request a cost map providing end-to-end available bandwidth, can request a cost map providing end-to-end available bandwidth,
using 'availbw' as cost-metric and 'numerical' as cost-mode. using "availbw" as cost-metric and "numerical" as cost-mode.
The application will receive from ALTO server that the bandwidth of The application will receive from ALTO server that the bandwidth of
eh1 -> eh2 and eh1 -> eh4 are both 100 Mbps. But this information is eh1 -> eh2 and eh1 -> eh4 are both 100 Mbps. But this information is
not enough. Consider the following two cases: not enough. Consider the following two cases:
o Case 1: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw6 -> o Case 1: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw6 ->
sw7 -> sw2 -> eh2 and eh1 -> eh4 uses path eh1 -> sw1 -> sw5 -> sw7 -> sw2 -> eh2 and eh1 -> eh4 uses path eh1 -> sw1 -> sw5 ->
sw7 -> sw4 -> eh4, then the application will obtain 150 Mbps. sw7 -> sw4 -> eh4, then the application will obtain 150 Mbps at
most.
o Case 2: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw7 -> o Case 2: If eh1 -> eh2 uses the path eh1 -> sw1 -> sw5 -> sw7 ->
sw2 -> eh2 and eh1 -> eh4 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. -> sw4 -> eh4, then the application will obtain only 100 Mbps at
most.
To allow applications to distinguish the two aforementioned cases, To allow applications to distinguish the two aforementioned cases,
the network needs to provide more details. In particular: the network needs to provide more details. In particular:
o The network needs to expose more detailed routing information to o The network needs to expose more detailed routing information to
show the shared bottlenecks. show the shared bottlenecks.
o The network needs to provide the necessary abstraction to hide the o The network needs to provide the necessary abstraction to hide the
real topology information while providing enough information to real topology information while providing enough information to
applications. applications.
The path-vector extension defined in this document meets all the The path vector extension defined in this document propose a solution
requirements. to provide these details.
See [I-D.bernstein-alto-topo] for a survey of use-cases where See [I-D.bernstein-alto-topo] for a more comprehensive survey of use
extended network topology information is needed. cases where extended network topology information is needed.
4. Overview of Path Vector Extensions 4. Overview of Path Vector Extensions
This section presents an overview of approaches adopted by the path This section presents an overview of approaches adopted by the path
vector extension. It assumes the readers are familiar with vector extension. It assumes the readers are familiar with cost map
(Filtered) Cost Map and Endpoint Cost Service defined in [RFC7285] and endpoint cost service defined in [RFC7285]. The path vector
and their extensions defined in [RFC8189]. The path vector extension extension also requires the support of Filtered Property Map defined
also requires the support of Filtered Property Map defined in in [I-D.ietf-alto-unified-props-new].
[I-D.ietf-alto-unified-props-new].
The path vector extension is composed of three building blocks: (1) a The path vector extension is composed of three building blocks: (1) a
new cost type to encode path vectors; (2) a new entity domain for new cost type to encode path vectors; (2) a new ALTO entity domain
unified property extension [I-D.ietf-alto-unified-props-new] to for unified property extension [I-D.ietf-alto-unified-props-new] to
encode properties of abstract network elements; and (3) a new service encode properties of ANEs; and (3) an extension to the cost map and
to provide path vector messages in a single session; endpoint cost resource to provide path vectors and properties of ANEs
in a single response.
4.1. New Cost Type to Encode Path Vectors 4.1. New Cost Type to Encode Path Vectors
Existing cost types defined in [RFC7285] only allow scalar cost Existing cost types defined in [RFC7285] allow only scalar cost
values, they cannot be used to convey vector format information. values. However, the "path vector" abstraction requires to convey
This document defines a new cost mode to enable the cost value to vector format information. To achieve this requirement, this
carry an array of elements, and a new cost metric to pass ANE names document defines a new cost mode to enable the cost value to carry an
as elements in the array. Detailed information and specifications array of elements, and a new cost metric to take names of ANEs as
are given in Section 5.1.1 and Section 5.1.2. elements in the array. We call such an array of ANEs a path vector.
In this way, the cost map and endpoint cost service can convey the
4.2. New Entity Domain to Provide ANE Properties path vector to represent the routing information. Detailed
information and specifications are given in Section 5.1 and
Section 5.2.
Given the new cost type introduced by Section 4.1, Cost Map and 4.2. New ALTO Entity Domain to Provide ANE Properties
Endpoint Cost Service can provide the ANE names along a flow path.
However, only providing the ANE names without properties is not
enough. To detect shared bottlenecks, ALTO clients may expect
information on specific ANE properties such as link capacity or
delay.
This document adopts the property map defined in The path vector can only represent the route between the source and
[I-D.ietf-alto-unified-props-new] to encode the properties of the destination. Although the application can find the shared ANEs
abstract network elements. A new domain "ane" is registered in the among different paths, it is not enough for most use cases, which
property map. Each entity in the "ane" domain has an identifier of requires the bandwidth or delay information of the ANEs. So this
an ANE. An ANE identifier is the ANE name used in the values of the document adopts the property map defined in
"ane-path" metric defined in the present draft. ANE properties are [I-D.ietf-alto-unified-props-new] to provide the general properties
provided in information resources called "Property Map Resource" and of ANEs. The document registers a new entity domain called "ane" to
"Filtered Property Map Resource". The "Filtered Property Map" represent the ANE. The address of the ANE entity is just the ANE
resource which supports the "ane" domain is used to encode the name used by the path vector. By requesting the property map of
properties of ane entities, and it is called an ANE Property Map in entities in the "ane" domain, the client can retrieve the properties
this document. of ANEs in path vectors.
4.3. New Service to Enable Multipart Resources 4.3. Extended Cost Map/Endpoint Cost Service for Compound Resources
In the base ALTO protocol, ALTO servers use media types in the HTTP Providing the path vector information and the ANE properties by
header to indicate the type of the response. Typically one response separated resources have several known benefits: (1) can be better
only contains a single media type, such as "application/alto- compatible with the base ALTO protocol; (2) can make different
costmap+json" or "application/alto-propmap+json". This has limited property map resources reuse the same cost map or endpoint cost
the capability of ALTO servers to return multiple map messages in a resource. However, it conducts two issues:
single response.
Thus, an ALTO client needs to make separate queries to get the o Efficiency: The separated resources will require the ALTO client
information of related services. This may cause a data to invoke multiple requests/responses to collect all needed
synchronization problem between dependent ALTO services because when information. It increases the communication overhead.
making the second query, the result for the first query may have
already changed. The same problem can happen to Network Map and Cost
Map resources. However, unlike Network Map and Cost Map which are
considered more stable, Path Vectors and the dependent ANE Property
Maps might change more frequently.
Instead of introducing a new media type to encapsulate multiple types o Consistency: The path vectors and properties of ANEs are
in a single response, this document adopts the "multipart/related" correlated. So querying them one by one may conduct consistency
media type defined in [RFC2387]. In this way, a response can contain issue. Once the path vector changes during the client requests
both the path vectors in a filtered cost map (or endpoint cost map) the ANE properties, the ANE properties may be inconsistent with
and the associated ANE Property Map. The media types of the cost map the previous path vector.
and the property map can still be retrieved from the response. The
interpretation of each media type in the "multipart/related" response
is consistent with the base ALTO protocol.
5. Path Vector Extension: Basic Data Types To solve these issues, this document introduces an extension to cost
map and endpoint cost service, which allows the ALTO server to attach
a property map in the data entry of a cost map or an endpoint cost
service response.
This section formally specifies a new cost type and a new entity These issues may exist in all general cases for querying separated
domain. ALTO information resources. But solving this general problem is not
in the scope of this document.
5.1. Cost Type 5. Cost Type
This document extends the cost types defined in Section 6.1 of This document extends the cost types defined in Section 6.1 of
[RFC7285] by introducing a new cost mode "array" and a new cost [RFC7285] by introducing a new cost mode "array" and a new cost
metric "ane-path". In the rest content, this document use "path- metric "ane-path". In the rest content, this document uses "path-
vector" to indicate the combination cost type of the cost mode vector" to indicate the combination cost type of the cost mode
"array" and the cost metric "ane-path". "array" and the cost metric "ane-path".
5.1.1. Cost Mode: array 5.1. Cost Mode: array
This document extends the CostMode defined in Section 10.5 of This document extends the CostMode defined in Section 10.5 of
[RFC7285] with a new cost mode: "array". This cost mode indicates [RFC7285] with a new cost mode: "array". This cost mode indicates
that every cost value in a cost map represents an array rather than a that every cost value in a cost map represents an array rather than a
simple value. The values are arrays of JSONValue. The specific type simple value. The values are arrays of JSONValue. The specific type
of each element in the array depends on the cost metric. of each element in the array depends on the cost metric.
5.1.2. Cost Metric: ane-path 5.2. Cost Metric: ane-path
This document specifies a new cost metric: "ane-path". This cost This document specifies a new cost metric: "ane-path". This cost
metric indicates that the cost value is a list of abstract network metric indicates that the cost value is a list of ANEs which the path
elements which the path from a source to a destination goes across. from a source to a destination goes across. The values are arrays of
The values are arrays of ANE names which are defined in Section 5.3. ANE names which are defined in Section 6.2.
The cost metric "ane-path" SHOULD NOT be used when the cost mode is The cost metric "ane-path" SHOULD NOT be used when the cost mode is
not "array" unless it is explicitly specified by a future extension. not "array" unless it is explicitly specified by a future extension.
If an ALTO client send queries with the cost metric "ane-path" and a If an ALTO client send queries with the cost metric "ane-path" and a
non "array" cost mode, the ALTO server SHOULD return an error with non "array" cost mode, the ALTO server SHOULD return an error with
the error code "E_INVALID_FIELD_VALUE"; If an ALTO server declares the error code "E_INVALID_FIELD_VALUE"; If an ALTO server declares
the support of a cost type with the cost metric "ane-path" and a non the support of a cost type with the cost metric "ane-path" and a non
"array" cost mode, the ALTO client SHOULD assume such a cost type is "array" cost mode, the ALTO client SHOULD assume such a cost type is
invalid and ignore it. invalid and ignore it.
5.1.3. Path Vector Cost Type Semantics 5.3. Path Vector Cost Type Semantics
The new cost type follows the convention of the cost types in the The new cost type follows the convention of the cost types in the
base ALTO protocol. Table 1 lists some of the current defined cost base ALTO protocol. Table 1 lists some of the current defined cost
types and their semantics. types and their semantics.
+------------+--------------+---------------------------------------+ +------------+--------------+---------------------------------------+
| Cost Mode | Cost Metric | Semantics | | Cost Mode | Cost Metric | Semantics |
+------------+--------------+---------------------------------------+ +------------+--------------+---------------------------------------+
| numerical | routingcost | a number representing the routing | | numerical | routingcost | a number representing the routing |
| | | cost | | | | cost |
skipping to change at page 10, line 28 skipping to change at page 10, line 9
The "routingcost" and "hopcount" can encoded in "numerical" or The "routingcost" and "hopcount" can encoded in "numerical" or
"ordinal", however, the cost metric "ane-path" can only be applied to "ordinal", however, the cost metric "ane-path" can only be applied to
the cost mode "array" defined in this document to convey path vector the cost mode "array" defined in this document to convey path vector
information. The cost metric "ane-path" can not be used in information. The cost metric "ane-path" can not be used in
"numerical" or "ordinal" unless it is defined in future extensions. "numerical" or "ordinal" unless it is defined in future extensions.
If the ALTO server declares that it support cost type with cost If the ALTO server declares that it support cost type with cost
metric being "ane-path" and cost mode not being "array", the ALTO metric being "ane-path" and cost mode not being "array", the ALTO
client SHOULD ignore them. client SHOULD ignore them.
5.2. ANE Domain 6. ANE Domain
This document specifies a new entity domain in addition to the ones This document specifies a new ALTO entity domain called "ane" in
in [I-D.ietf-alto-unified-props-new]. addition to the ones in [I-D.ietf-alto-unified-props-new]. The ANE
domain associates property values with the ANEs in a network. The
entity in ANE domain is often used in the path vector by cost maps or
endpoint cost resources. Accordingly, the ANE domain always depends
on a cost map or an endpoint cost map.
5.2.1. Domain Name 6.1. Domain Name
ane ane
5.2.2. Domain-Specific Entity Addresses 6.2. Domain-Specific Entity Addresses
The entity address of ane domain is encoded as a JSON string. The The entity address of ane domain is encoded as a JSON string. The
string MUST be no more than 64 characters, and it MUST NOT contain string MUST be no more than 64 characters, and it MUST NOT contain
characters other than US-ASCII alphanumeric characters characters other than US-ASCII alphanumeric characters
(U+0030-U+0039, U+0041-U+005A, and U+0061-U+007A), the hyphen ("-", (U+0030-U+0039, U+0041-U+005A, and U+0061-U+007A), the hyphen ("-",
U+002D), the colon (":", U+003A), the at sign ("@", code point U+002D), the colon (":", U+003A), the at sign ("@", code point
U+0040), the low line ("_", U+005F), or the "." separator (U+002E). U+0040), the low line ("_", U+005F), or the "." separator (U+002E).
The "." separator is reserved for future use and MUST NOT be used The "." separator is reserved for future use and MUST NOT be used
unless specifically indicated in this document, or an extension unless specifically indicated in this document, or an extension
document. document.
5.2.3. Hierarchy and Inheritance To simplify the description, we use "ANE name" to indicate the
address of an entity in ANE domain in this document.
There is no hierarchy or inheritance for properties associated with
ANEs.
5.3. Abstract Network Element Name
An Abstract Network Element Name is encoded as an EntityAddr of the
"ane" domain as defined in Section 3.4.2 of
[I-D.ietf-alto-unified-props-new].
6. Path Vector Extension: Services
This section extends Filtered Cost Map Service and Endpoint Cost
Service. It also introduce a new service called "Multipart Cost
Property Service".
6.1. Filtered Cost Map Extensions
This document extends the Filtered Cost Map defined in Section 4.1 of
[RFC8189].
The specifications for the "media type", "HTTP method" and "uses" are
the same as defined in Section 4.1 of [RFC8189].
6.1.1. Capabilities
The FilteredCostMapCapabilities object is extended with a new member
"property-map":
object {
[ResourceID property-map;]
} PathVectorFilteredCostMapCapabilities : FilteredCostMapCapabilities
property-map: A resource ID defined in the same IRD pointing to an
ANE Property Map as defined in Section 2. This field MUST be
present if the path vector cost type is present in the "cost-type-
names" field.
Other fields of the FilteredCostMapCapabilities object has the same
format as defined in Section 4.1.1 of [RFC8189] with the following
restriction:
testable-cost-type-names: The path vector cost type with "ane-path"
as the cost metric and "array" as the cost mode MUST NOT be
included in "testable-cost-type-names".
6.1.2. Accept Input Parameters
The ReqFilteredCostMap uses the same format as defined in The ANE name is usually unrelated to the physical device information.
Section 4.1.2 of [RFC8189], with the following restrictions: It is usually generated by the ALTO server on demand and used to
distinguish from other ANEs in its dependent cost map or endpoint
cost map.
constraints, or-constraints: If the path vector cost type is 6.3. Hierarchy and Inheritance
included in either "cost-type" or "multi-cost-types", ALTO clients
MUST NOT use it in "constraints" or "or-constraints". Otherwise,
the ALTO server MUST return an error with error code
"E_INVALID_FIELD_VALUE".
testable-cost-types: The path vector cost type MUST NOT be included There is no hierarchy or inheritance for properties associated with
in the "testable-cost-types" field. Otherwise, the ALTO server ANEs.
MUST return an error with error code "E_INVALID_FIELD_VALUE".
6.1.3. Response 7. Protocol Extensions for Path Vector Compound Query
If the ALTO client includes the cost type "path-vector" in the "cost- To make the ALTO client query the path vectors and properties of ANEs
type" or "multi-cost-types" field of the input parameter, the efficiently and consistently, this document extends the Filtered Cost
response use the same format as defined in Section 4.1.3 of Map and Endpoint Cost Service.
[RFC8189], but the corresponding cost value MUST be encoded as a
JSONArray of AbstractNetworkElementName.
6.2. Endpoint Cost Service Extensions 7.1. Filtered Cost Map Extensions
This document extends the Endpoint Cost Service defined in This document extends Filtered Cost Map, as defined in Section 11.3.2
Section 4.2 in [RFC8189]. of [RFC7285], by adding new input parameters and capabilities, and by
augmenting the property map into the data entry of the response.
The specifications for "HTTP method", "media-type" and "uses" are the The "media type", "HTTP method", and "uses" specifications (described
same as defined in Section 4.2 in [RFC8189]. in Sections 11.3.2.1, 11.3.2.2, and 11.3.2.5 of [RFC7285],
respectively) remain the same.
6.2.1. Capabilities 7.1.1. Capabilities
The same as defined in Section 6.1.1. The Filtered Cost Map capabilities are extended with two new members:
6.2.2. Accept Input Parameters o dependent-property-map
The ReqEndpointCostMap uses the same format as defined in o allow-compound-response
Section 4.2.2 of [RFC8189], with the following restrictions:
cost-type, multi-cost-types: ALTO clients MUST include the path The capability "dependent-property-map" indicates which property map
vector cost type, e.g. the one with "ane-path" as cost metric and this resource depends on, and the capability "allow-compound-
"array" as cost mode, in either "cost-type" or "multi-cost-types" response" indicates whether the ALTO server supports the resource to
to activate the path vector extension. compound the property map with its own response data. With these two
additional members, the FilteredCostMapCapabilities object in
Section 11.3.2.4 of [RFC7285] is extended as follows:
constraints, or-constraints: If the path vector cost type is object {
included in either "cost-type" or "multi-cost-types", ALTO clients [ResourceID dependent-property-map;]
MUST NOT use it in "constraints" or "or-constraints". Otherwise, [JSONBool allow-compound-response;]
the ALTO server MUST return an error with error code } PVFCMCapabilities : FilteredCostMapCapabilities;
"E_INVALID_FIELD_VALUE".
testable-cost-types: The path vector cost type MUST NOT be included dependent-property-map: This field MUST be specified when the "cost-
in the "testable-cost-types" field. Otherwise, the ALTO server type-names" includes a cost type name indicating a "ane-path"
MUST return an error with error code "E_INVALID_FIELD_VALUE". metric. Its value MUST be a resource id indicating a property map
including "ane" domain. If not, the ALTO client SHOULD consider
this resource is invalid.
6.2.3. Response allow-compound-response: If present, the true value means the ALTO
client can request the resource to augment its dependent property
map into the response automatically; the false value means the
ALTO client cannot request the compound response. If omitted, the
default value is false;
If the ALTO client specifies the path vector cost type in the "cost- To be noticed that the capability "cost-constraints" is unexpected
type" or "multi-cost-types" field of the input parameter, the for the "array" cost mode. The syntax and semantics of constraint
response use the same format as defined in Section 4.2.3 of tests on the "array" cost mode depends on the implementation and can
[RFC8189], but the corresponding cost value MUST be encoded as a be defined in the future documents. But it is not in the scope of
JSONArray of AbstractNetworkElementName. this document.
6.3. Multipart Cost Property Service 7.1.2. Accept Input Parameters
This document introduces a new ALTO service called "Multipart Cost The ReqFilteredCostMap object in Section 11.3.2.3 of [RFC7285] is
Property Service", which provides the path vector information and the extended as follows:
associated ANE property information in the same response.
6.3.1. Media Type object {
[PropertyName compound-properties<1..*>;]
} ReqPVFilteredCostMap : ReqFilteredCostMap;
The media type of the Multipart Cost Property service is "multipart/ compound-properties: If the capability "allow-compound-response" is
related". false, the ALTO client MUST NOT specify this field, and the ALTO
server MUST reject the request and return "E_INVALID_FILED_VALUE"
error when it receives a request including this field. If this
field is specified and accepted, the ALTO server MUST augment the
dependent property map with the properties in this field into the
response automatically.
6.3.2. HTTP Method 7.1.3. Response
The Multipart Cost Property service is requested using the HTTP POST If the ALTO client specifies the "cost-type" input parameter with
method. "ane-path" metric, the "dependent-vtags" field in the "meta" field of
the response MUST include the version tag of its dependent property
map following its dependent network map.
6.3.3. Accept Input Parameters If the ALTO client specifies the "compound-properties" input
parameter which is accepted by the ALTO server, the response MUST
include a "property-map" field following the "cost-map" field, and
its value MUST be a PropertyMapData object. This PropertyMapData
object MUST be equivalent to the result when query the dependent
property map resource using the following request: the "entities"
field includes all the ANE names appearing in the cost values of the
"cost-map" field, the "properties" field has the same value as the
"compound-properties" field does. The properties shown in the
"compound-properties" input parameter but are not supported by the
dependent property map SHOULD be omitted from the response.
The input parameters of the Multipart Cost Property service MUST be 7.2. Endpoint Cost Service Extensions
encoded as a JSON object in the body of an HTTP POST request. The
media type of the request SHOULD be one of "application/alto-
costmapfilter+json" and "application/alto-endpointcostparams+json".
The format of the request body depends on the media type:
o If the media type of the request is "application/alto- This document extends the Endpoint Cost Service, as defined in
costmapfilter+json", the request body MUST be the same type as Section 11.5.1 of [RFC7285], by adding new input parameters and
defined by Section 6.1.2. capabilities and by augmenting the property map into the data entry
of the response.
o If the media type of the request is "application/alto- The media type, HTTP method, and "uses" specifications (described in
endpointcostparams+json", the request body MUST be the same type Sections 11.5.1.1, 11.5.1.2, and 11.5.1.5 of [RFC7285], respectively)
as defined by Section 6.2.2. are unchanged.
The path vector cost type MUST be the only cost type in the input 7.2.1. Capabilities
parameter.
6.3.4. Capabilities The extensions to the Endpoint Cost Service capabilities are
identical to the extensions to the Filtered Cost Map (see
Section 7.1.1).
TBD 7.2.2. Accept Input Parameters
6.3.5. Uses The ReqEndpointCostMap object in Section 11.5.1.3 of [RFC7285] is
extended as follows:
The "uses" attribute MUST be an array with at least one resource id. object {
The first resource id MUST point to a Filtered Cost Map or an [PropertyName compound-properties<1..*>;]
Endpoint Cost Service resource. And the path vector cost type MUST } ReqPVEndpointCostMap : ReqEndpointCostMap;
be in its "cost-type" capability. If there are more than one
resource id in the "uses" attribute, the ALTO client SHOULD ignore
any additional resource ids.
According to Section 6.1.1, the "property-map" field MUST be present The "compound-properties" has the same interpretation as defined in
in the first resource. So the ALTO client MUST infer that the Section 7.1.2
Property Map pointed by the "property-map" field of the first
resource is also a dependent resource.
6.3.6. Response 7.2.3. Response
If an ALTO client sends a request of the media type "application/ If the ALTO client specifies the "cost-type" input parameter with
alto-costmapfilter+json" and accepts "multipart/related", the HTTP "ane-path" metric, the response MUST include the "meta" field with
body of the response MUST consist of two parts with the media types the "dependent-vtags" in it, and the "dependent-vtags" field MUST
"application/alto-costmap+json" and "application/alto-propmap+json" include the version tag of its dependent property map.
accordingly. The part with media type "application/alto-
costmap+json" MUST be the first part. The content of the
"application/alto-endpointcost+json" part has the same format as
defined in Section 6.1.3.
If an ALTO client sends a request of the media type "application/ If the ALTO client specifies the "compound-properties" input
alto-endpointcostparams+json" and accepts "multipart/related", the parameter which is accepted by the ALTO server, the response MUST
HTTP body of the response MUST consist of two parts with the media include a "property-map" field following the "endpoint-cost-map"
types "application/alto-endpointcost+json" and "application/alto- field, and its value MUST be a PropertyMapData object. This
propmap+json" accordingly. The part with media type "application/ PropertyMapData object MUST be equivalent to the result when query
alto-endpointcost+json" MUST be the first part. The content of the the dependent property map resource using the following request: the
"application/alto-endpointcost+json" part has the same format as "entities" field includes all the ANE names appearing in the cost
defined in Section 6.2.3. values of the "endpoint-cost-map" field, the "properties" field has
the same value as the "compound-properties" field does. The
properties shown in the "compound-properties" input parameter but are
not supported by the dependent property map SHOULD be omitted from
the response.
7. Examples 8. Examples
This section lists some examples of path vector queries and the This section lists some examples of path vector queries and the
corresponding responses. corresponding responses.
7.1. Workflow 8.1. Workflow
This section gives a typical workflow of an ALTO client using the This section gives a typical workflow of how an ALTO client query
path-vector extension. path vectors using the extension.
1. Send a GET request for the whole Information Resource Directory. 1. Send a GET request for the whole Information Resource Directory.
2. Look for the resource of the (Filtered) Cost Map/Endpoint Cost 2. Look for the resource of the (Filtered) Cost Map/Endpoint Cost
Service which contains the path vector cost type and get the Service which supports the "ane-path" cost metric and get the
resource ID of the dependent abstract network element property resource ID of the dependent property map.
map.
3. Check whether the capabilities of the property map includes the 3. Check whether the capabilities of the property map includes the
desired "prop-types". desired "prop-types".
4. Send a path-vector request which accepts "multipart/related" 4. Check whether the (Filtered) Cost Map/Endpoint Cost Service
media type following "application/alto-costmap+json" or allows the compound response.
"application/endpointcost+json".
7.2. Information Resource Directory Example 1. If allowed, the ALTO client can send a request including the
desired ANE properties to the ALTO server and receive a
compound response with the cost map/endpoint cost map and the
property map.
2. If not allowed, the ALTO client sends a query for the cost
map/endpoint cost map first. After receiving the response,
the ALTO client interprets all the ANE names appearing in the
response and sends another query for the property map on
those ANE names.
8.2. Information Resource Directory Example
Here is an example of an Information Resource Directory. In this Here is an example of an Information Resource Directory. In this
example, filtered cost map "cost-map-pv" doesn't support the multi- example, filtered cost map "cost-map-pv" doesn't support the multi-
cost extension but support the path-vector extension, "endpoint- cost extension but support the path-vector extension, "endpoint-
multicost-map" supports both multi-cost extension and path-vector multicost-map" supports both multi-cost extension and path-vector
extension. Filtered Property Map "propmap-delay-availbw" supports extension. Filtered Property Map "propmap-availbw-delay" supports
properties "availbw" and "delay", and "propmap-location" supports properties "availbw" and "delay".
property "location".
{ {
"meta": { "meta": {
"cost-types": { "cost-types": {
"pv": { "path-vector": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"num-routingcost": { "num-routingcost": {
"cost-mode": "numerical", "cost-mode": "numerical",
"cost-metric": "routingcost" "cost-metric": "routingcost"
}, },
"num-hopcount": { "num-hopcount": {
"cost-mode": "numerical", "cost-mode": "numerical",
"cost-metric": "hopcount" "cost-metric": "hopcount"
skipping to change at page 15, line 50 skipping to change at page 15, line 4
}, },
"num-routingcost": { "num-routingcost": {
"cost-mode": "numerical", "cost-mode": "numerical",
"cost-metric": "routingcost" "cost-metric": "routingcost"
}, },
"num-hopcount": { "num-hopcount": {
"cost-mode": "numerical", "cost-mode": "numerical",
"cost-metric": "hopcount" "cost-metric": "hopcount"
} }
} }
}, },
"resources": { "resources": {
"my-default-networkmap": { "my-default-networkmap": {
"uri" : "http://alto.example.com/networkmap", "uri" : "http://alto.example.com/networkmap",
"media-type" : "application/alto-networkmap+json" "media-type" : "application/alto-networkmap+json"
} },
"cost-map-pv" : { "my-default-cost-map": {
"uri": "http://alto.example.com/costmap/pv", "uri": "http://alto.example.com/costmap/pv",
"media-type": "application/alto-costmap+json", "media-type": "application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json", "accepts": "application/alto-costmapfilter+json",
"capabilities": { "capabilities": {
"cost-type-names": [ "pv", "num-hopcount" ] "cost-type-names": [ "num-hopcount",
"num-routingcost" ]
}, },
"property-map": "propmap-delay",
"uses": [ "my-default-networkmap" ] "uses": [ "my-default-networkmap" ]
}, },
"endpoint-multicost-map" : { "cost-map-pv": {
"uri": "http://alto.exmaple.com/endpointcostmap/multicost", "uri": "http://alto.example.com/costmap/pv",
"media-type": "application/alto-endpointcost+json", "media-type": "application/alto-costmap+json",
"accepts": "application/alto-endpointcostparams+json", "accepts": "application/alto-costmapfilter+json",
"capabilities": { "capabilities": {
"cost-constraints": true, "cost-type-names": [ "path-vector" ],
"cost-type-names": [ "pv", "num-routingcost" ], "dependent-property-map": "propmap-availbw-delay"
"max-cost-types": 2
}, },
"property-map": "propmap-availbw" "uses": [ "my-default-networkmap" ]
}, },
"propmap-availbw-delay" : { "endpoint-cost-pv": {
"uri": "http://alto.exmaple.com/propmap/availbw", "uri": "http://alto.exmaple.com/endpointcost/pv",
"media-type": "application/alto-propmap+json", "media-type": "application/alto-endpointcost+json",
"accepts": "application/alto-propmapparams+json", "accepts": "application/alto-endpointcostparams+json",
"capabilities": { "capabilities": {
"domain-types": [ "ane" ], "cost-type-names": [ "path-vector" ],
"prop-types": [ "availbw" ] "dependent-property-map": "propmap-availbw-delay",
"allow-compound-response": true
} }
}, },
"propmap-location" : { "invalid-cost-map" : {
"uri": "http://alto.exmaple.com/propmap/delay", "uri": "http://alto.example.com/costmap/invalid",
"media-type": "application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json",
"capabilities": {
"cost-type-names": [ "path-vector" ],
"allow-compound-response": true
},
"uses": [ "my-default-networkmap" ]
},
"propmap-availbw-delay": {
"uri": "http://alto.exmaple.com/propmap/ane-prop",
"media-type": "application/alto-propmap+json", "media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json", "accepts": "application/alto-propmapparams+json",
"capabilities": { "capabilities": {
"domain-types": [ "pid" ], "domain-types": [ "ane" ],
"prop-types": [ "location" ] "prop-types": [ "availbw", "delay" ]
} },
"uses": [ "cost-map-pv", "endpoint-cost-pv" ]
} }
} }
} }
7.3. Example # 1 8.3. Example # 1
Query filtered cost map to get the path vectors.
POST /costmap/pv HTTP/1.1 POST /costmap/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related, application/alto-costmap+json, Accept: application/alto-costmap+json,
application/alto-propmap+json, application/alto-error+json application/alto-error+json
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: application/alto-costmapfilter+json Content-Type: application/alto-costmapfilter+json
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"pids": { "pids": {
"srcs": [ "PID1" ], "srcs": [ "PID1" ],
skipping to change at page 17, line 24 skipping to change at page 17, line 4
{ {
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
"pids": { "pids": {
"srcs": [ "PID1" ], "srcs": [ "PID1" ],
"dsts": [ "PID2", "PID3" ] "dsts": [ "PID2", "PID3" ]
} }
} }
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: multipart/related; boundary=42
--42
Content-Type: application/alto-costmap+json Content-Type: application/alto-costmap+json
{ {
"meta": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "default-network-map", "resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f622838ce670f" "tag": "75ed013b3cb58f896e839582504f622838ce670f"
} }
], ],
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, }
}, },
"cost-map": { "cost-map": {
"PID1": { "PID1": {
"PID2": [ "ane:L001", "ane:L003" ], "PID2": [ "ane:L001", "ane:L003" ],
"PID3": [ "ane:L001", "ane:L004" ] "PID3": [ "ane:L001", "ane:L004" ]
} }
} }
} }
--42
Then query the properties of ANEs in path vectors.
POST /propmap/ane-prop HTTP/1.1
Host: alto.example.com
Accept: application/alto-propmap+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-propmapparams+json
{
"entities": [ "ane:L001", "ane:L003", "ane:L004" ],
"properties": [ "delay" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-propmap+json Content-Type: application/alto-propmap+json
{ {
"meta": {
"dependent-vtags": [
{
"resource-id": "cost-map-pv",
"tag": "a7d57e120ab63124e3c9a82f7a54bc120fc96216"
}
]
},
"property-map": { "property-map": {
"ane:L001": { "delay": 46}, "ane:L001": { "delay": 46},
"ane:L003": { "delay": 50}, "ane:L003": { "delay": 50},
"ane:L004": { "delay": 70} "ane:L004": { "delay": 70}
} }
} }
--42-- 8.4. Example # 2
7.4. Example # 2 POST /endpointcost/pv HTTP/1.1
Host: alto.example.com
Accept: application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
POST /endpointcostmap/multicost HTTP/1.1 {
Host: alto.example.com "multi-cost-types": [
Accept: multipart/related, application/alto-endpointcost+json, {
application/alto-propmap+json, application/alto-error+json "cost-mode": "array",
Content-Length: [TBD] "cost-metric": "ane-path"
Content-Type: application/alto-endpointcostparams+json },
{
"cost-mode": "numerical",
"cost-metric": "routingcost"
}
],
"endpoints": {
"srcs": [ "ipv4:192.0.2.2" ],
"dsts": [ "ipv4:192.0.2.89",
"ipv4:203.0.113.45",
"ipv6:2001:db8::10" ]
}
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-endpointcost+json
{ {
"multi-cost-types": [ "meta": {
{ "cost-type": [
"cost-mode": "array", {"cost-mode": "array", "cost-metric": "ane-path"}
"cost-metric": "ane-path" ]
}, },
{ "endpoint-cost-map": {
"cost-mode": "numerical", "ipv4:192.0.2.2": {
"cost-metric": "routingcost" "ipv4:192.0.2.89": [ "ane:L001", "ane:L003",
} "ane:L004" ],
], "ipv4:203.0.113.45": [ "ane:L001", "ane:L004",
"endpoints": { "ane:L005" ],
"srcs": [ "ipv4:192.0.2.2" ], "ipv6:2001:db8::10": [ "ane:L001", "ane:L005",
"dsts": [ "ipv4:192.0.2.89", "ane:L007" ]
"ipv4:203.0.113.45", }
"ipv6:2001:db8::10" ] }
} }
}
HTTP/1.1 200 OK POST /endpointcost/pv HTTP/1.1
Content-Length: [TBD] Host: alto.example.com
Content-Type: multipart/related; boundary=example-2 Accept: application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
Content-Type: application/alto-endpointcost+json {
{ "entities": [ "ane:L001", "ane:L003", "ane:L004",
"meta": { "ane:L005", "ane:L007" ],
"multi-cost-types": [ "properties": [ "availbw" ]
{"cost-mode": "array", "cost-metric": "ane-path"}, }
{"cost-mode": "numerical", "cost-metric": "routingcost"} HTTP/1.1 200 OK
] Content-Length: [TBD]
}, Content-Type: application/alto-propmap+json
"endpoint-cost-map": { {
"ipv4:192.0.2.2": { "meta": {
"ipv4:192.0.2.89": [[ "ane:L001", "ane:L003", "ane:L004" ], 77], "dependent-vtags": [
"ipv4:203.0.113.45": [[ "ane:L001", "ane:L004", "ane:L005" ], 68], {
"ipv6:2001:db8::10": [[ "ane:L001", "ane:L005", "ane:L007" ], 98] "resource-id": "endpoint-cost-pv",
} "tag": "12c0889c3c0892bb67df561ed16d93f5d1fa75cf"
} }
} ]
},
"property-map": {
"ane:L001": { "availbw": 50 },
"ane:L003": { "availbw": 48 },
"ane:L004": { "availbw": 55 },
"ane:L005": { "availbw": 60 },
"ane:L007": { "availbw": 35 }
}
}
Content-Type: application/alto-propmap+json 8.5. Example #3
POST /endpointcost/pv HTTP/1.1
Host: alto.example.com
Accept: application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{ {
"property-map": { "multi-cost-types": [
"ane:L001": { "availbw": 50 }, {
"ane:L003": { "availbw": 48 }, "cost-mode": "array",
"ane:L004": { "availbw": 55 }, "cost-metric": "ane-path"
"ane:L005": { "availbw": 60 }, },
"ane:L007": { "availbw": 35 } {
} "cost-mode": "numerical",
} "cost-metric": "routingcost"
}
],
"endpoints": {
"srcs": [ "ipv4:192.0.2.2" ],
"dsts": [ "ipv4:192.0.2.89",
"ipv4:203.0.113.45",
"ipv6:2001:db8::10" ]
},
"properties": [ "delay", "availbw" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-endpointcost+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "propmap-availbw-delay",
"tag": "bb6bb72eafe8f9bdc4f335c7ed3b10822a391cef"
}
],
"cost-type": [
{"cost-mode": "array", "cost-metric": "ane-path"}
]
},
"endpoint-cost-map": {
"ipv4:192.0.2.2": {
"ipv4:192.0.2.89": [ "ane:L001", "ane:L003",
"ane:L004" ],
"ipv4:203.0.113.45": [ "ane:L001", "ane:L004",
"ane:L005" ],
"ipv6:2001:db8::10": [ "ane:L001", "ane:L005",
"ane:L007" ]
}
},
"property-map": {
"ane:L001": { "availbw": 50, "delay": 46 },
"ane:L003": { "availbw": 48, "delay": 50 },
"ane:L004": { "availbw": 55, "delay": 70 },
"ane:L005": { "availbw": 60, "delay": 100 },
"ane:L007": { "availbw": 35, "delay": 100 }
}
}
8. Compatibility 9. Compatibility
8.1. Compatibility with Legacy ALTO Clients/Servers 9.1. Compatibility with Legacy ALTO Clients/Servers
The path vector extension on Filtered Cost Map and Endpoint Cost The path vector extension on Filtered Cost Map and Endpoint Cost
Service is backward compatible with the base ALTO protocol. If the Service is backward compatible with the base ALTO protocol:
ALTO server provides path vector extended Filtered Cost Map or
Endpoint Cost Service, but the client is a base ALTO client, then the
client will ignore the path vector cost type without conducting any
incompatibility. If the client sents a request with path vector cost
type, but the server is a base ALTO server, the server will return an
"E_INVALID_FIELD_VALUE" error.
8.2. Compatibility with Multi-Cost Extensions o If the ALTO server provides extended capabilities "dependent-
property-map" and "allow-compound-response" for Filtered Cost Map
or Endpoint Cost Service, but the client only supports the base
ALTO protocol, then the client will ignore those capabilities
without conducting any incompatibility.
Cost type path-vector is not a testable cost type. Any format of o If the client sends a request with the input parameter
constraints SHOULD NOT be applied to cost type path-vector in order "properties", but the server only supports the base ALTO protocol,
for multi-cost to support the path-vector extension. Specifically, the server will ignore this field.
o Cost type path-vector MUST NOT be included in "testable-cost- 9.2. Compatibility with Multi-Cost Extension
types-names" or "testable-cost-types".
o When "testable-cost-types-names" is omitted in the "capabilities" This document does not specify how to integrate the "array" cost mode
and "testable-cost-types" is omitted in the input parameters, and the "ane-path" cost metric with the multi-cost extension
"constraints" or "or-constraints" SHOULD NOT add any format of [RFC8189]. Although there is no reason why somebody has to compound
constraints on cost type path-vector. the path vectors with other cost types in a single query, there is no
compatible issue doing it without constraint tests.
8.3. Compatibility with Incremental Update As Section 7.1.1 mentions, the syntax and semantics of whether
"constraints" or "or-constraints" field for the "array" cost mode is
not specified in this document. So if an ALTO server provides a
resource with the "array" cost mode and the capability "cost-
constraints" or "testable-cost-types-names", the ALTO client MAY
ignore the capability "cost-constraints" or "testable-cost-types-
names" unless the implementation or future docuements specify the
behavior.
[I-D.ietf-alto-incr-update-sse] defines incremental updates to ALTO 9.3. Compatibility with Incremental Update
resources and hence it can be applied to the path-vector resource
defined in this document.
9. Design Decisions and Discussions As this document still follows the basic request/response protocol
with JSON encoding, it is surely compatible with the incremental
update service as defined by [I-D.ietf-alto-incr-update-sse]. But
the following details are to be noticed:
9.1. Provide More General Calendar Extension o When using the compound response, updates on both cost map and
property map SHOULD be notified.
Cost Calendar is proposed as a useful ALTO extension to provide the o When not using the compound response, because the cost map is in
historical cost values for Filtered Cost Map Service and Endpoint the "uses" attribute of the property map, once the path vectors in
Cost Service. Since path vector is an extension to these services, the cost map change, the ALTO server MUST send the updates of the
it SHOULD be compatible with Cost Calendar extension. cost map before the updates of the property map.
However, the calendar of a path-vector (Endpoint) Cost Map is 10. General Discussions
insufficient for the application which requires the historical data
of routing state information. The (Endpoint) Cost Map can only
provide the changes of the paths. But more useful information is the
history of network element properties which are recorded in the
dependent Network Element Property Map.
Before the Unified Property Map is introduced as an ALTO extension, 10.1. Provide Calendar for Property Map
Filtered Cost Map Service and Endpoint Cost Service are the only
resources which require the calendar supported. Because other
resources don't have to be updated frequently. But Network Element
Property Map as a use case of Unified Property Map will collect the
real-time information of the network. It SHOULD be updated as soon
as possible once the metrics of network elements change.
So the requirement is to provide a general calendar extension which Fetching the historical network information is useful for many
not only meets the Filtered Cost Map and Endpoint Cost Service but traffic optimization problem. [I-D.ietf-alto-cost-calendar] already
also applies to the Property Map Service. proposes an ALTO extension called Cost Calendar which provides the
historical cost values using Filtered Cost Map and Endpoint Cost
Service. However, the calendar for only path costs is not enough.
10. Security Considerations For example, as the properties of ANEs (e.g., available bandwidth and
link delay) are usually the real-time network states, they change
frequently in the real network. It is very helpful to get the
historical value of these properties. Applications may predicate the
network status using these information to better optimize their
performance.
10.1. Privacy Concerns So the coming requirement may be a general calendar service for the
ALTO information resources.
10.2. 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 defined syntax is too simple and can only be
used to test the scalar cost value. For more complex cost types,
like the "array" mode defined in this document, it does not work
well. It will be helpful to propose more general constraint tests to
better perform the query.
In practice, it is too complex to customize a language for the
general-purpose boolean tests, and can be a duplicated work. So it
may be a good idea to integrate some already defined and widely used
query languages (or their subset) to solve this problem. The
candidates can be XQuery and JSONiq.
10.3. General Compound Resources Query
As the last paragraph of Section 4.3 mentions, querying multiple ALTO
information resources continuously is 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
11.1. Privacy Concerns
We can identify multiple potential security issues. A main security We can identify multiple potential security issues. A main security
issue is network privacy, as the path-vector information may reveal issue is network privacy, as the path vector information may reveal
more network internal structures than the more abstract single-node more network internal structures than the more abstract single-node
abstraction. The network should consider protection mechanisms to abstraction. The network should consider protection mechanisms to
reduce information exposure, in particular, in settings where the reduce information exposure, in particular, in settings where the
network and the application do not belong to the same trust domain. network and the application do not belong to the same trust domain.
On the other hand, in a setting of the same trust domain, a key On the other hand, in a setting of the same trust domain, a key
benefit of the path-vector abstraction is reduced information benefit of the path-vector abstraction is reduced information
transfer from the network to the application. transfer from the network to the application.
The path-vector query may also reveal more information about the Beyond the privacy issues, the computation of the path vector is
application. In particular, the application may reveal all potential unlikely to be cacheable, in that the results will depend on the
transfers sites (e.g., where the data source is replicated, and where
the potential replication sites are). The application should
evaluate the potential privacy concerns.
Beyond the privacy issues, the computation of the path-vector is
unlikely to be cachable, in that the results will depend on the
particular requests (e.g., where the flows are distributed). Hence, particular requests (e.g., where the flows are distributed). Hence,
this service may become an entry point for denial of service attacks this service may become an entry point for denial of service attacks
on the availability of an ALTO server. Hence, authenticity and on the availability of an ALTO server. Hence, authenticity and
authorization of this ALTO service may need to be better protected. authorization of this ALTO service may need to be better protected.
10.2. Resource Consumption on ALTO Servers 11.2. Resource Consumption on ALTO Servers
TODO: The Abstract Network Element Property Map is dynamically The dependent Property Map of path vectors is dynamically enriched
enriched when the (Filtered) Cost Map/Endpoint Cost Service is when the (Filtered) Cost Map/Endpoint Cost Service is queried of the
queried of the path-vector information. The properties of the path-vector information. The properties of the abstract network
abstract network elements can consume a large amount of resources elements can consume a large amount of resources when cached. So, a
when cached. So, a time-to-live is needed to remove outdated entries time-to-live is needed to remove outdated entries in the Abstract
in the Abstract Network Element Property Map. Network Element Property Map.
11. IANA Considerations 12. IANA Considerations
11.1. ALTO Cost Mode Registry 12.1. ALTO Cost Mode Registry
This document specifies a new cost mode "array". However, the base This document specifies a new cost mode "array". However, the base
ALTO protocol does not have a Cost Mode Registry where new cost mode ALTO protocol does not have a Cost Mode Registry where new cost mode
can be registered. This new cost mode will be registered once the can be registered. This new cost mode will be registered once the
registry is defined either in a revised version of [RFC7285] or in registry is defined either in a revised version of [RFC7285] or in
another future extension. another future extension.
11.2. ALTO Cost Metric Registry 12.2. ALTO Cost Metric Registry
A new cost metric needs to be registered in the "ALTO Cost Metric A new cost metric needs to be registered in the "ALTO Cost Metric
Registry", listed in Table 2. Registry", listed in Table 2.
+-------------+---------------------+ +-------------+---------------------+
| Identifier | Intended Semantics | | Identifier | Intended Semantics |
+-------------+---------------------+ +-------------+---------------------+
| ane-path | See Section 5.1.2 | | ane-path | See Section 5.2 |
+-------------+---------------------+ +-------------+---------------------+
Table 2: ALTO Cost Metrics Table 2: ALTO Cost Metrics
11.3. ALTO Entity Domain Registry 12.3. ALTO Domain Registry
As proposed in Section 9.2 of [I-D.ietf-alto-unified-props-new], As proposed in Section 9.2 of [I-D.ietf-alto-unified-props-new],
"ALTO Entity Domain Registry" is requested. Besides, a new domain is "ALTO Domain Registry" is requested. Besides, a new domain is to be
to be registered, listed in Table 3. registered, listed in Table 3.
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
| Identifier | Entity Address Encoding | Hierarchy & Inheritance | | Identifier | Entity Address Encoding | Hierarchy & Inheritance |
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
| ane | See Section 5.2.2 | None | | ane | See Section 6.2 | None |
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
Table 3: ALTO Entity Domain Table 3: ALTO Domain
11.4. ALTO Network Element Property Type Registry 12.4. ALTO Network Element Property Type Registry
The "ALTO Abstract Network Element Property Type Registry" is The "ALTO Abstract Network Element Property Type Registry" is
required by the ALTO Entity Domain "ane", listed in Table 4. required by the ALTO Domain "ane", listed in Table 4.
+-------------+--------------------------+ +-------------+--------------------------+
| Identifier | Intended Semantics | | Identifier | Intended Semantics |
+-------------+--------------------------+ +-------------+--------------------------+
| availbw | The available bandwidth | | availbw | The available bandwidth |
| delay | The transmission delay | | delay | The transmission delay |
+-------------+--------------------------+ +-------------+--------------------------+
Table 4: ALTO Abstract Network Element Property Types Table 4: ALTO Abstract Network Element Property Types
12. Acknowledgments 13. Acknowledgments
The authors would like to thank discussions with Randriamasy Sabine, The authors would like to thank discussions with Randriamasy Sabine,
Andreas Voellmy, Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao Andreas Voellmy, Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao
Xiang, Tianyuan Liu, Xiao Shi, Xin Wang, and Yan Luo. Xiang, Tianyuan Liu, Xiao Shi, Xin Wang, and Yan Luo.
13. References 14. References
13.1. Normative References 14.1. Normative References
[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, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
13.2. Informative References 14.2. Informative References
[I-D.amante-i2rs-topology-use-cases] [I-D.amante-i2rs-topology-use-cases]
Medved, J., Previdi, S., Lopez, V., and S. Amante, Medved, J., Previdi, S., Lopez, V., and S. Amante,
"Topology API Use Cases", draft-amante-i2rs-topology-use- "Topology API Use Cases", draft-amante-i2rs-topology-use-
cases-01 (work in progress), October 2013. cases-01 (work in progress), October 2013.
[I-D.bernstein-alto-topo] [I-D.bernstein-alto-topo]
Bernstein, G., Yang, Y., and Y. Lee, "ALTO Topology Bernstein, G., Yang, Y., and Y. Lee, "ALTO Topology
Service: Uses Cases, Requirements, and Framework", draft- Service: Uses Cases, Requirements, and Framework", draft-
bernstein-alto-topo-00 (work in progress), October 2013. bernstein-alto-topo-00 (work in progress), October 2013.
skipping to change at page 24, line 5 skipping to change at page 27, line 33
"ALTO Extensions to Support Application and Network "ALTO Extensions to Support Application and Network
Resource Information Exchange for High Bandwidth Resource Information Exchange for High Bandwidth
Applications in TE networks", draft-lee-alto-app-net-info- Applications in TE networks", draft-lee-alto-app-net-info-
exchange-04 (work in progress), October 2013. exchange-04 (work in progress), October 2013.
[I-D.yang-alto-topology] [I-D.yang-alto-topology]
Bernstein, G., Lee, Y., Roome, W., Scharf, M., and Y. Bernstein, G., Lee, Y., Roome, W., Scharf, M., and Y.
Yang, "ALTO Topology Extensions: Node-Link Graphs", draft- Yang, "ALTO Topology Extensions: Node-Link Graphs", draft-
yang-alto-topology-06 (work in progress), March 2015. yang-alto-topology-06 (work in progress), March 2015.
[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., [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy, Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol", "Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014, RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>. <https://www.rfc-editor.org/info/rfc7285>.
[RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost [RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
Application-Layer Traffic Optimization (ALTO)", RFC 8189, Application-Layer Traffic Optimization (ALTO)", RFC 8189,
DOI 10.17487/RFC8189, October 2017, <https://www.rfc- DOI 10.17487/RFC8189, October 2017,
editor.org/info/rfc8189>. <https://www.rfc-editor.org/info/rfc8189>.
Authors' Addresses Authors' Addresses
Greg Bernstein Greg Bernstein
Grotto Networking Grotto Networking
Fremont, CA Fremont, CA
USA USA
Email: gregb@grotto-networking.com Email: gregb@grotto-networking.com
Shiwei Dawn Chen Shiwei Dawn Chen
Tongji University Tongji University
4800 Caoan Road 4800 Caoan Road
Shanghai 201804 Shanghai 201804
China China
Email: dawn_chen_f@hotmail.com Email: dawn_chen_f@hotmail.com
Kai Gao Kai Gao
Tsinghua University Tsinghua University
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