draft-ietf-alto-path-vector-01.txt   draft-ietf-alto-path-vector-02.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: January 4, 2018 Tongji University Expires: June 21, 2018 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
July 3, 2017 December 18, 2017
ALTO Extension: Path Vector Cost Mode ALTO Extension: Path Vector Cost Type
draft-ietf-alto-path-vector-01.txt draft-ietf-alto-path-vector-02.txt
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 several resources and services to provide clients with
basic network information. However, the base ALTO protocol and basic network information. However, the base ALTO protocol and
latest extensions only provide end-to-end metrics, which are latest extensions only provide end-to-end metrics, which are
insufficient to satisfy the demands of solving more complex network insufficient to satisfy the demands of solving more complex network
optimization problems. This document introduces an extension to the optimization problems. This document introduces an extension to the
base ALTO protocol, namely the path-vector extension, which allows base ALTO protocol, namely the path-vector extension, which allows
skipping to change at page 2, line 15 skipping to change at page 2, line 15
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 4, 2018. This Internet-Draft will expire on June 21, 2018.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Use Case: Capacity Region for Multi-Flow Scheduling . . . . . 5 3. Use Case: Capacity Region for Multi-Flow Scheduling . . . . . 5
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4. Overview of Path Vector Extensions . . . . . . . . . . . . . 7
4.1. Path Vector . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Path Vector Cost Type Extensions . . . . . . . . . . . . 7
4.2. Cost Type Extension . . . . . . . . . . . . . . . . . . . 8 4.1.1. New Cost Metric for Path Vector . . . . . . . . . . . 7
4.3. Abstract Network Element Property Map . . . . . . . . . . 8 4.1.2. New Cost Mode for Path Vector . . . . . . . . . . . . 8
4.4. New Media Type: multipart/related . . . . . . . . . . . . 8 4.1.3. Path Vector Cost Type Semantics . . . . . . . . . . . 8
5. Path-Vector Extension: Basic Data Types . . . . . . . . . . . 9 4.2. ANE Property Map . . . . . . . . . . . . . . . . . . . . 8
5.1. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3. media type for path vector: multipart/related . . . . . . 9
5.1.1. Cost Metric . . . . . . . . . . . . . . . . . . . . . 9 4.4. Applicable ALTO services for Path Vector costs . . . . . 9
5.1.2. Cost Mode . . . . . . . . . . . . . . . . . . . . . . 10 4.5. Impact of backwards compatibility on the PV design . . . 10
5.2. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . 10 4.6. Requirements for PV on Clients and Servers . . . . . . . 10
5.2.1. Domain Name . . . . . . . . . . . . . . . . . . . . . 10 5. Path-Vector Extension: Basic Data Types . . . . . . . . . . . 10
5.2.2. Domain-Specific Entity Addresses . . . . . . . . . . 10 5.1. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1.1. Cost Mode: array . . . . . . . . . . . . . . . . . . 11
5.1.2. Cost Metric: ane-path . . . . . . . . . . . . . . . . 11
5.2. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Abstract Network Element Name . . . . . . . . . . . . . . 11 5.3. Abstract Network Element Name . . . . . . . . . . . . . . 11
5.4. Version Tag . . . . . . . . . . . . . . . . . . . . . . . 11
6. Path-Vector Extension: Services . . . . . . . . . . . . . . . 11 6. Path-Vector Extension: Services . . . . . . . . . . . . . . . 11
6.1. IRD Extensions . . . . . . . . . . . . . . . . . . . . . 11 6.1. Filtered Cost Map Extensions . . . . . . . . . . . . . . 11
6.2. Cost Map Extensions . . . . . . . . . . . . . . . . . . . 12 6.1.1. Capabilities . . . . . . . . . . . . . . . . . . . . 12
6.2.1. Media Type . . . . . . . . . . . . . . . . . . . . . 12 6.1.2. Accept Input Parameters . . . . . . . . . . . . . . . 12
6.2.2. Capabilities . . . . . . . . . . . . . . . . . . . . 12 6.1.3. Response . . . . . . . . . . . . . . . . . . . . . . 12
6.2.3. Property-map . . . . . . . . . . . . . . . . . . . . 12 6.2. Endpoint Cost Service Extensions . . . . . . . . . . . . 13
6.2.4. Response . . . . . . . . . . . . . . . . . . . . . . 13 6.2.1. Capabilities . . . . . . . . . . . . . . . . . . . . 13
6.3. Filtered Cost Map Extensions . . . . . . . . . . . . . . 13 6.2.2. Accept Input Parameters . . . . . . . . . . . . . . . 13
6.3.1. Media Type . . . . . . . . . . . . . . . . . . . . . 13 6.2.3. Response . . . . . . . . . . . . . . . . . . . . . . 13
6.3.2. Capabilities . . . . . . . . . . . . . . . . . . . . 13 6.3. Multipart Cost Property Service . . . . . . . . . . . . . 13
6.3.3. Property-map . . . . . . . . . . . . . . . . . . . . 14 6.3.1. Media Type . . . . . . . . . . . . . . . . . . . . . 14
6.3.4. Accept Input Parameters . . . . . . . . . . . . . . . 14 6.3.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . 14
6.3.5. Response . . . . . . . . . . . . . . . . . . . . . . 14 6.3.3. Accept Input Parameters . . . . . . . . . . . . . . . 14
6.4. Endpoint Cost Service Extensions . . . . . . . . . . . . 14 6.3.4. Capabilities . . . . . . . . . . . . . . . . . . . . 14
6.4.1. Media Type . . . . . . . . . . . . . . . . . . . . . 15 6.3.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . 14
6.4.2. Capabilities . . . . . . . . . . . . . . . . . . . . 15 6.3.6. Response . . . . . . . . . . . . . . . . . . . . . . 15
6.4.3. Property-map . . . . . . . . . . . . . . . . . . . . 15 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.4.4. Accept Input Parameters . . . . . . . . . . . . . . . 15 7.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 15
6.4.5. Response . . . . . . . . . . . . . . . . . . . . . . 15 7.2. Information Resource Directory Example . . . . . . . . . 16
7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.3. Example # 1 . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 16 7.4. Example # 2 . . . . . . . . . . . . . . . . . . . . . . . 18
7.2. Information Resource Directory Example . . . . . . . . . 17 8. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 20
7.3. Single Query Example # 1 . . . . . . . . . . . . . . . . 18 8.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 20
7.4. Single Query Example # 2 . . . . . . . . . . . . . . . . 20 8.2. Compatibility with Multi-Cost Extensions . . . . . . . . 20
7.5. Multiple Queries Example . . . . . . . . . . . . . . . . 21 8.3. Compatibility with Incremental Update . . . . . . . . . . 20
7.5.1. Endpoint Cost Service Example . . . . . . . . . . . . 21 9. Design Decisions and Discussions . . . . . . . . . . . . . . 21
7.5.2. Abstract Network Element Property Map Example . . . . 23 9.1. Provide More General Calendar Extension . . . . . . . . . 21
8. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 23 10. Security Considerations . . . . . . . . . . . . . . . . . . . 21
8.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 23 10.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 21
8.2. Compatibility with Multi-Cost Extensions . . . . . . . . 23 10.2. Resource Consumption on ALTO Servers . . . . . . . . . . 22
8.3. Compatibility with Incremental Update . . . . . . . . . . 24 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
9. Design Decisions and Discussions . . . . . . . . . . . . . . 24 11.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 22
9.1. Provide More General Calendar Extension . . . . . . . . . 24 11.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 22
10. Security Considerations . . . . . . . . . . . . . . . . . . . 24 11.3. ALTO Network Element Property Type Registry . . . . . . 22
10.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . 24 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
10.2. Resource Consumption on ALTO Servers . . . . . . . . . . 25 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 13.1. Normative References . . . . . . . . . . . . . . . . . . 23
11.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 25 13.2. Informative References . . . . . . . . . . . . . . . . . 23
11.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
11.3. ALTO Entity Domain Registry . . . . . . . . . . . . . . 26
11.4. ALTO Network Element Property Type Registry . . . . . . 26
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
13.1. Normative References . . . . . . . . . . . . . . . . . . 27
13.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
The ALTO base protocol [RFC7285] is designed for exposing network The base ALTO protocol [RFC7285] is designed for exposing network
information through services such as the Network Map service and the information through services such as the Network Map service and the
Cost Map service. These services use an extreme "single-node" Cost Map service. These services use an extreme "single-node"
abstraction, which represents the whole network with a single node network view abstraction, which represents the whole network with a
and hosts with "endpoint groups" directly connected to the node. single node and hosts with "endpoint groups" directly connected to
the node.
Although the "single-node" abstraction works well in many settings,
it lacks the ability to support new emerging use cases, such as
inter-datacenter flow scheduling and scientific high-performance
computing data transfers. Specifically, the base ALTO protocol MUST
provide the following two functionalities:
o Providing information on shared bottlenecks: In the aforementioned Although the "single-node" network view abstraction works well in
use cases, the volume of a single flow can reach 10s - 100s Gbps, many settings, it lacks the ability to support new emerging use
so that the network cannot treat the flows as independent like in cases, such as inter-datacenter flow scheduling, scientific high-
the base ALTO protocol. In this case, ALTO servers MUST be able performance computing data transfers and end-to-end paths crossing
to provide information on shared bottlenecks to help applications heterogeneous technologies. For these use cases, more powerful
avoid congestion. network view abstraction is required. To provide a better network
view abstraction, ALTO services need to support the following
additional functionalities:
o Encapsulating multiple cost values in a single session: Some flow o Providing path vector rather than a simple path cost of endpoint
scheduling problems take multiple metrics into consideration. to endpoint. The path vector exposes the network elements (e.g.,
Making multiple queries introduces larger communication overhead, links, switches, middle boxes and their aggregations) that
and more importantly, out-of-sync data for different cost types. endpoint to endpoint traffic goes through.
Encapsulating multiple cost values in a single query and response
session reduces communication overhead and simplifies the
synchronization in use cases involving multiple cost types.
This draft aims to extend the base ALTO protocol to support these new o Providing information of the network elements in the path vector.
functionalities, with the path-vector extension. The path-vector The information can be "bandwidth" for links, "delay" between
extension specifies how to encode the shared bottlenecks in a network neighboring switches and other properties of network elements.
for a given set of flows with many design details driven by These information may help the application avoid network
effectiveness, performance and backward compatibility considerations. congestion, achieving better application performance.
The second functionality for simple cost types, such as those To support these new functionalities, this document proposes the
introduced in the base protocol, is already addressed in a recent path-vector extension, which introduces a qualitative cost type
extension, e.g. [I-D.ietf-alto-multi-cost]. However, the path- listing selected groups of one or more abstracted network elements in
vector extension in this document has introduced a new cost type an e2e path and optionally conveys some of their properties.
which complicates the situation. Thus, the multiple cost
encapsulation must still be taken into consideration.
The document is organized as follows. Section 3 gives an example of The rest of this document is organized as follows. Section 3 gives
flow scheduling and illustrates the limitations of the base ALTO an example of flow scheduling and illustrates the limitations of the
protocol in such a use case. Section 4 gives an overview of the base ALTO protocol in such a use case. Section 4 gives an overview
path-vector extension, before specifying the details of the extension of the path-vector extension, before specifying the details of the
in Section 5 and Section 6. Section 7 presents several examples, and extension in Section 5 and Section 6. Section 7 presents several
Section 9 explains some design decisions. Section 8 discusses examples, and Section 9 explains some design decisions. Section 8
compatibility issues with some other ALTO extensions. Section 10 and discusses compatibility issues with some other ALTO extensions.
Section 11 discusses about security and IANA considerations. Section 10 and Section 11 discusses about security and IANA
considerations.
2. Terminology 2. Terminology
This document uses the same terms as defined in [RFC7285], This document uses the same terms as defined in [RFC7285], [RFC8189]
[I-D.ietf-alto-multi-cost] and [I-D.roome-alto-unified-props] with and [I-D.ietf-alto-unified-props-new] with the following additional
the following additional terms: Abstract Network Element, Abstract terms: Abstract Network Element, Abstract Network Element Name,
Network Element Name, Abstract Network Element Property, Abstract Abstract Network Element Property, Abstract Network Element Property
Network Element Property Map and Path Vector. Map 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), or even a
sub-network. An abstract network element has two attributes: sub-network. An abstract network element has two attributes:
abstract network element name and abstract network element abstract network element name and abstract network element
property, which are defined below. property, which are defined below.
o Abstract Network Element Name (ANEN): An abstract network element o Abstract Network Element Name (ANEN): An abstract network element
name is an identifier which uniquely identifies an abstract name is an identifier which uniquely identifies an abstract
network element, as defined in Section 5.3. network element, as defined in Section 5.3.
o Abstract Network Element Property (ANEP): An abstract network o Abstract Network Element Property (ANEP): An abstract network
element property is a specific metric associated with a given element property is a specific metric associated with a given
abstract network element, as introduced in Section 4.3. An abstract network element, as introduced in Section 4.2. An
abstract network element CAN have several network element abstract network element can have several network element
properties. properties.
o Abstract Network Element Property Map (ANEP Map): An abstract o Abstract Network Element Property Map (ANE Property Map): An
network element property map is a Filtered Property Map defined in abstract network element property map is a Filtered Property Map
[I-D.roome-alto-unified-props] which supports the "ane" domain in defined in [I-D.ietf-alto-unified-props-new] which supports the
its "domain-types" capability. "ane" domain in its "domain-types" capability.
o Path Vector (PV): A path vector is an array of abstract network o Path Vector (PV): A path vector is an array of ALTO Abstract
elements, representing an abstract path between entities (PIDs or Network Elements (ANEs), which presents an abstract network path
endpoints). between entities such as PIDs or endpoints. An ANE represents a
selected part of an end-to-end path that the ALTO Server considers
worth exposing. An ANE is a set of one or more network elements
such as links, switches, middle boxes and their aggregations, it
is expected to have properties that may influence the applications
e.g. when they select an endpoint or want to estimate their
performance.
3. Use Case: Capacity Region for Multi-Flow Scheduling 3. Use Case: Capacity Region for Multi-Flow Scheduling
Consider the case that routing is given. Then what application-layer Once routing has been configured in the network, application-layer
traffic optimization will focus on is traffic scheduling among traffic optimization may want to schedule traffic among application-
application-layer paths. Specifically, assume that an application layer paths. Specifically, assume that an application has control
has control over a set of flows F = {f_1, f_2, ..., f_|F|}. If over a set of flows F = {f_1, f_2, ..., f_|F|}. If routing is given,
routing is given, what the application can control is x_1, x_2, ..., what the application can control is x_1, x_2, ..., x_|F|, where x_i
x_|F|, where x_i is the amount of traffic for flow i. Let x = [x_1, is the amount of traffic for flow i. Let x = [x_1, ..., x_|F|] be
..., x_|F|] be the vector of the flow traffic amounts. Due to shared the vector of the flow traffic amounts. Due to shared links,
links, feasible values of x where link capacities are not exceeded feasible values of x where link capacities are not exceeded can be a
can be a complex polytype. complex polytype.
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. End hosts eh1 to eh4 are other side, and sw5-sw7 form the backbone. End hosts 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 47 skipping to change at page 6, line 39
| | | |
{eh3} | | {eh4} {eh3} | | {eh4}
PID3 | | PID4 PID3 | | PID4
+------+ +------+ +------+ +------+
| | | |
+----------------------+ +----------------------+
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 needs 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.
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.
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, it needs the network needs to provide more details. In particular:
to provide the following new capabilities:
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 as possible. real topology information while providing enough information to
applications.
The path-vector extension defined in this document will satisfy all The path-vector extension defined in this document meets all the
the requirements. requirements.
See [I-D.bernstein-alto-topo] for a survey of use-cases where See [I-D.bernstein-alto-topo] for a survey of use-cases where
extended network topology information is needed. extended network topology information is needed.
4. Overview 4. Overview of Path Vector Extensions
This section presents a non-normative overview of the path-vector This section presents the approaches taken to support the path-vector
extension. It assumes the readers are familiar with (Filtered) Cost extension. It assumes the readers are familiar with (Filtered) Cost
Map and Endpoint Cost Service defined in [RFC7285], their extensions Map and Endpoint Cost Service defined in [RFC7285] and their
defined in [I-D.ietf-alto-multi-cost] and Filtered Property Map extensions defined in [RFC8189]. It also uses features such as
defined in [I-D.roome-alto-unified-props]. Filtered Property Map defined in [I-D.ietf-alto-unified-props-new].
4.1. Path Vector 4.1. Path Vector Cost Type Extensions
A path vector is an array of abstract network elements, representing None of current cost types defined in [RFC7285] can be used to convey
an abstract path between entities (PIDs or endpoints). Each abstract path vector information. So, a new cost type with a new cost metric
network element has two attributes: name and property. The abstract "ane-path" and a new cost mode "array" is defined in this document.
network element names are encoded in cost maps and the abstract Below are brief descriptions. Detailed information and
network element properties are encoded in abstract network element specifications are given in Section 5.1.1 and Section 5.1.2.
property maps.
4.2. Cost Type Extension 4.1.1. New Cost Metric for Path Vector
To provide abstract network element names of a path in cost maps, To represent an abstract network path, this document introduces a new
each cost value is a list of abstract network element names. cost metric named "ane-path". A cost value in this metric is a list
However, as defined in Section 6.1.2 of [RFC7285], a cost mode is containing the names of the ALTO ANEs that the ALTO Server has
either "numerical" or "ordinal", none of which can be used to present specified as describing the network path elements. The ANE names
a list. array is organized as a sequence beginning at the source of the path
and ending at its destination.
This document specifies a new cost mode "array" and a new cost metric 4.1.2. New Cost Mode for Path Vector
"ane-path". The new cost mode "array" means each cost value in the
cost maps is a list. The new cost metric "ane-path" means each cost A cost mode as defined in Section 6.1.2 of [RFC7285], a cost mode is
value represents an abstract path consisting of abstract network either "numerical" or "ordinal" and none of these can be used to
element names between two entities (PIDs or endpoints). present a list of ANE names. Therefore, this document specifies a
new cost mode named "array" for the cost metric "ane-path". The new
cost mode "array" means each cost value in the cost maps is a list.
4.1.3. 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 protocol. For example: legacy ALTO protocol. Table 1 lists some of the current defined cost
types and their semantics.
+------------+--------------+---------------------------------------+ +------------+--------------+---------------------------------------+
| cost mode | cost metric | meaning | | Cost Mode | Cost Metric | Semantics |
+------------+--------------+---------------------------------------+ +------------+--------------+---------------------------------------+
| numerical | routingcost | a number representing the routing | | numerical | routingcost | a number representing the routing |
| | | cost | | | | cost |
| numerical | hopcount | a number representing the hop count |
| ordinal | routingcost | a ranking representing the routing |
| | | cost |
| ordinal | hopcount | a ranking representing the hop count | | ordinal | hopcount | a ranking representing the hop count |
| array | ane-path | a list representing the ane path | | array | ane-path | a list representing the ane path |
+------------+--------------+---------------------------------------+ +------------+--------------+---------------------------------------+
Table 1: Cost Types and Their Meanings Table 1: Cost Types and Their Semantics
4.3. Abstract Network Element Property Map The "routingcost" and "hopcount" can encoded in "numerical" or
"ordinal", however, the cost metric "ane-path" can only be applied to
the cost mode "array" defined in this document to convey path vector
information. The cost metric "ane-path" can not be used in
"numerical" or "ordinal" unless it is defined in future extensions.
If the ALTO server declares that it support cost type with cost
metric being "ane-path" and cost mode not being "array", the ALTO
client SHOULD ignore them.
4.2. ANE Property Map
Given that Cost Map and Endpoint Cost service now provide the Given that Cost Map and Endpoint Cost service now provide the
abstract network element names along a flow path, ALTO clients can abstract network element names along a flow path, ALTO clients can
learn that there exist bottlenecks between different flows. However, learn that there exist bottlenecks shared by different flows.
only providing the abstract network element names without abstract However, only providing the abstract network element names without
network element properties is not enough, because ALTO clients often abstract network element properties is not enough, some ALTO clients
require the information on specific metric values like the link may want to have information on specific ANE properties such as link
capacity. This document adopts the property map defined in a recent capacity or delay. This document adopts the property map resources
draft [I-D.roome-alto-unified-props] to encode the properties of defined in [I-D.ietf-alto-unified-props-new] to encode the properties
abstract network elements. A new domain "ane" is registered in the of ANEs. Draft [I-D.ietf-alto-unified-props-new] defines a new
property map. Each entity in the "ane" domain is an abstract network entity domain called "ane" and each entity in the "ane" domain has an
element. The property map which supports "ane" domain is an Abstract identifier of an ANE. An ANE identifier is the ANE name used in the
Network Element Property Map. values of the "ane-path" metric defined in the present draft. ANE
properties are provided in information resources called "Property Map
Resource" and "Filtered Property Map Resource". The "Filtered
Property Map" resource which support the "ane" domain is used to
encode the properties of ane entities, and it is called an ANE
Property Map in this document.
4.4. New Media Type: multipart/related 4.3. media type for path vector: multipart/related
In the base ALTO protocol, ALTO servers use media types in the HTTP In the legacy ALTO protocol, ALTO servers use media types in the HTTP
header to indicate the type of the response. Typically one response header to indicate the type of the response. Typically one response
only contains a single media type, such as "application/alto- only contains a single media type, such as "application/alto-
costmap+json" or "application/alto-propmap+json". This has limited costmap+json" or "application/alto-propmap+json". This has limited
the capability of ALTO servers to return multiple services in a the capability of ALTO servers to return multiple services in a
single response. single response.
Thus, an ALTO client MUST make multiple queries to get the Thus, an ALTO client needs to make separate queries to get the
information from services of different types. This has led to the information of related services. This may cause a data
data synchronization problem between dependent ALTO services because synchronization problem between dependent ALTO services because when
when making the second query, the result for the first query may have making the second query, the result for the first query may have
already changed. The very same problem can happen to Network Map and already changed. The very same problem can happen to Network Map and
Cost Map resources. However, unlike Network Map and Cost Map which Cost Map resources. However, unlike Network Map and Cost Map which
are considered more stable, path vectors and the dependent abstract are considered more stable, Path Vectors and the dependent ANE
network element property maps might change more frequently. Property Maps might change more frequently.
Instead of introducing a new media type to encapsulate multiple types Instead of introducing a new media type to encapsulate multiple types
in a single response, this documents adopts the "multipart" media in a single response, this document adopts the "multipart/related"
type defined in [RFC2387]. Thus, a response can contain both the media type defined in [RFC2387]. In this way, a response can contain
path vector as a Cost Map (or Endpoint Cost Map) and the both the Path Vectors in a Filtered Cost Map (or Endpoint Cost Map)
corresponding abstract network element property map as a Property and the associated ANE Property Map. The media types of the cost map
Map. The media types of the path vector and the abstract network and the property map can still be retrieved from the response. The
element property map can still be retrieved from the response, interpretation of each media type in the "multipart/related" response
achieving consistency with the base ALTO protocol. is consistent with the base ALTO protocol.
For backward compatibility, this extension also allows ALTO clients
to make multiple queries instead of encapsulating abstract network
element property map along with the path vector. Thus, each Cost Map
or Endpoint Cost Service with this extension MUST include a "prop-
map" in their capabilities to indicate where to retrieve the network
element properties. An additional field "query-id" MUST also be
added to the "vtag" field to uniquely identify a path vector query
session.
5. Path-Vector Extension: Basic Data Types
This section formally specifies the path-vector extension of some 4.4. Applicable ALTO services for Path Vector costs
basic data types.
5.1. Cost Type This document defines Filtered Cost Map and Endpoint Cost Map are
applicable for path vector costs. Although the new cost type for
path vector can also be used in the GET-mode Cost Map service from
[RFC7285], the behaviours of the ALTO server and client for such a
GET-mode service is not defined. So it is not recommended to apply
path vector costs to the GET-mode Cost Map service.
This document extends the cost types defined in Section 6.1 of 4.5. Impact of backwards compatibility on the PV design
[RFC7285] by introducing a new cost mode "array" and a new cost
metric "ane-path".
5.1.1. Cost Metric The path vector extension on Filtered Cost Map and Endpoint Cost
Service is backward compatible with the base ALTO protocol. If the
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.
This document specifies a new cost metric: "ane-path". It is of type 4.6. Requirements for PV on Clients and Servers
CostMetric as defined in Section 10.6 of [RFC7285]. The cost metric
"ane-path" MUST NOT be used when the cost mode is not "array" unless
it is explicitly specified by a future extension. Meanwhile, an ALTO
server with path-vector extension MUST support the cost metric "ane-
path".
Cost metric "ane-path": This cost metric MUST be encoded as the A path vector extended ALTO server MUST implement the legacy ALTO
JSONString "ane-path". protocol specified in [RFC7285] with the following additional
requirements:
5.1.2. Cost Mode o If an ALTO server supports path vector extension, it MUST support
the Unified Property Map defined in
[I-D.ietf-alto-unified-props-new].
This document extends the CostMode defined in Section 10.5 of o If an ALTO server supports path vector extended Filtered Cost Map
[RFC7285] with a new cost mode: "array". The extended CostMode is or Endpoint Cost Service, the server MUST provide the associated
encoded as a string and MUST have a value of either "numerical", Property Map simultaneously.
"ordinal" or "array" unless it is explicitly specified by a future
extension. In particular, this extension has specified that when the
cost metric is "ane-path", the cost value MUST be interpreted as a
JSONArray of Abstract Network Element Names (defined in Section 5.3).
An ALTO cost service MUST return a JSONArray of JSONValue when the o If an ALTO server provides "multipart/related" media type for path
cost mode is "array" unless the interpretation is explicitly vector, the server MUST provide the associated Filtered Cost Map
specified by an ALTO extension. or Endpoint Cost Service and the Property Map simultaneously.
Cost mode "array": This cost mode MUST be encoded as the JSONString An ALTO client supported path vector extension MUST be able to
"array". interpret Unified Property Map correctly. If the ALTO client wants
to interpret "multipart/related" path vector response, the client
MUST implement the path vector extension on Filtered Cost Map or
Endpoint Cost Service at first.
5.2. ANE Domain 5. Path-Vector Extension: Basic Data Types
This document specifies a new domain in addition to the ones in [I- This section formally specifies a new cost type.
D.roome-alto-unified-props].
5.2.1. Domain Name 5.1. Cost Type
ane This document extends the cost types defined in Section 6.1 of
[RFC7285] by introducing a new cost mode "array" and a new cost
metric "ane-path".
5.2.2. Domain-Specific Entity Addresses 5.1.1. Cost Mode: array
The entity address of ane domain is encoded as a JSON string. The This document extends the CostMode defined in Section 10.5 of
string MUST be no more than 64 characters, and it MUST NOT contain [RFC7285] with a new cost mode: "array". This cost mode indicates
characters other than US-ASCII alphanumeric characters that every cost value in a cost map represents an array rather than a
(U+0030-U+0039, U+0041-U+005A, and U+0061-U+007A), the hyphen ('-', simple value. The values are arrays of JSONValue. The specific type
U+002D), the colon (':', U+003A), the at sign ('@', code point of each element in the array depends on the cost metric.
U+0040), the low line ('_', U+005F), or the '.' separator (U+002E).
The '.' separator is reserved for future use and MUST NOT be used
unless specifically indicated in this document, or an extension
document.
5.3. Abstract Network Element Name 5.1.2. Cost Metric: ane-path
An Abstract Network Element Name MUST be encoded as an EntityAddr as This document specifies a new cost metric: "ane-path". This cost
defined in Section 5.2.2. It MUST belong to the "ane" domain. metric indicates that the cost value is a list of abstract network
elements which the path from a source to a destination goes across.
The values are arrays of ANE Names which are defined in Section 5.3.
5.4. Version Tag 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.
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
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
"array" cost mode, the ALTO client SHOULD assume such a cost type is
invalid and ignore it.
This document extends the VersionTag, previously defined in 5.2. ANE Domain
Section 10.3 of [RFC7285] with an optional field "query-id". If an
ALTO cost service supports the path-vector extension, this field MUST
be included in the "vtag" field, and the "vtag" field MUST be
included in the "meta" field in the response in order to provide the
"query-id" information.
object { This document uses the same definition of entity domain name 'ane' as
ResourceID resource-id; defined in Section 3.4 of [I-D.ietf-alto-unified-props-new].
JSONString tag;
[JSONString query-id;]
} VersionTag;
resource-id, tag: As defined in Section 10.3 of [RFC7285]. 5.3. Abstract Network Element Name
query-id: A string used to uniquely identify the abstract network An Abstract Network Element Name is encoded as an EntityAddr of the
element names in the response and correlate abstract network "ane" domain as defined in Section 3.4.2 of
element names with abstract network element properties. A "query- [I-D.ietf-alto-unified-props-new].
id" MUST be encoded in the same format as defined in Section 10.1
of [RFC7285].
6. Path-Vector Extension: Services 6. Path-Vector Extension: Services
This section extends IRDResourceEntry, Cost Map Service and Endpoint This section extends Filtered Cost Map Service and Endpoint Cost
Cost Service. Service.
6.1. IRD Extensions
This document extends IRDResourceEntry defined in Section 9.2.2 of
[RFC7285] by introducing a new entry named "property-map", which
indicates where the specific properties of the abstract network
elements can be retrieved. The IRDResourceEntry object is extended
as follows:
object {
JSONString uri;
JSONString media-type;
[JSONString accepts;]
[Capabilities capabilities;]
[ResourceID uses<0..*>;]
[ResourceID property-map;]
} IRDResourceEntry;
uri, media-type, accepts, capabilities, uses: The same as defined in
Section 9.2.2 of [RFC7285].
property-map: A resource ID defined in the same IRD pointing to an
abstract network element property map as defined in Section 2.
6.2. Cost Map Extensions
This document extends the Cost Map defined in Section 11.2.3 of
[RFC7285].
The specifications for "HTTP method", "accept input parameters" and
"uses" are the same as defined in Section 11.2.3 of [RFC7285].
6.2.1. Media Type
The path vector extension now enables ALTO clients to receive
multiple services in a cost map response.
Specifically, if an ALTO client accepts "multipart/related",
"application/alto-costmap+json" and "application/alto-propmap+json"
at the same time, the ALTO server MUST use "multipart/related" as the
media type in the HTTP header.
6.2.2. Capabilities
If a service supports the path-vector extension, the "cost-type-
names" field MUST include a single cost type with "ane-path" as cost
metric and "array" as cost mode.
6.2.3. Property-map
If a service supports the path-vector extension, the "property-map"
field MUST be specified. This field is a resource ID of an abstract
network element property map where the abstract network element
properties are provided.
6.2.4. Response
If an ALTO client accepts "multipart/related" as defined in
Section 6.3.1, HTTP body of the response MUST consists of two parts
with the media types "application/alto-costmap+json" and
"application/alto-propmap+json" accordingly. Specifically, the part
with media type "application/alto-costmap+json" MUST be the first
part.
The content of the "application/alto-costmap+json" part uses the
format in Section 11.2.3.6 of [RFC7285] with the following
constraints:
o The cost value for a path vector query, e.g. the cost mode is
"array" and the cost metric is "ane-path", MUST be encoded as a
JSONArray of AbstractNetworkElementName.
o If the query sent by the client includes cost type path vector,
the "vtag" field defined in Section 5.4 has to be included in the
response. And the "query-id" information in "vtag" MUST be
provided to ALTO clients.
6.3. Filtered Cost Map Extensions 6.1. Filtered Cost Map Extensions
This document extends the Filtered Cost Map defined in Section 4.1 of This document extends the Filtered Cost Map defined in Section 4.1 of
[I-D.ietf-alto-multi-cost]. [RFC8189].
The specifications for "HTTP method" and "uses" are the same as The specifications for the "media type", "HTTP method" and "uses" are
defined in Section 4.1 of [I-D.ietf-alto-multi-cost]. the same as defined in Section 4.1 of [RFC8189].
6.3.1. Media Type 6.1.1. Capabilities
The same as Section 6.2.1. The FilteredCostMapCapabilities object is extended with a new member
"property-map":
6.3.2. Capabilities object {
[ResourceID property-map;]
} PathVectorFilteredCostMapCapabilities : FilteredCostMapCapabilities
The FilteredCostMapCapabilities object has the same format as defined property-map: A resource ID defined in the same IRD pointing to an
in Section 4.1.1 of [I-D.ietf-alto-multi-cost] with the following 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
constraint: constraint:
testable-cost-type-names: The path vector cost type with "ane-path" 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 as the cost metric and "array" as the cost mode MUST NOT be
included in "testable-cost-type-names". included in "testable-cost-type-names".
6.3.3. Property-map 6.1.2. Accept Input Parameters
The same as Section 6.2.3.
6.3.4. Accept Input Parameters
The ReqFilteredCostMap uses the same format as defined in The ReqFilteredCostMap uses the same format as defined in
Section 4.1.2 of [I-D.ietf-alto-multi-cost], with the following Section 4.1.2 of [RFC8189], with the following constraints:
constraints:
constraints, or-constraints: If the path vector cost type is constraints, or-constraints: If the path vector cost type is
included in either "cost-type" or "multi-cost-types", ALTO clients included in either "cost-type" or "multi-cost-types", ALTO clients
MUST NOT use it in "constraints" or "or-constraints". Otherwise, MUST NOT use it in "constraints" or "or-constraints". Otherwise,
the ALTO server MUST return an error with error code the ALTO server MUST return an error with error code
"E_INVALID_FIELD_VALUE". "E_INVALID_FIELD_VALUE".
testable-cost-types: The path vector cost type MUST NOT be included testable-cost-types: The path vector cost type MUST NOT be included
in the "testable-cost-types" field. Otherwise, the ALTO server in the "testable-cost-types" field. Otherwise, the ALTO server
MUST return an error with error code "E_INVALID_FIELD_VALUE". MUST return an error with error code "E_INVALID_FIELD_VALUE".
6.3.5. Response 6.1.3. Response
If an ALTO client accepts "multipart/related" as defined in
Section 6.3.1, HTTP body of the response MUST consist of two parts
with the media types "application/alto-costmap+json" and
"application/alto-propmap+json" accordingly. Specifically, the part
with media type "application/alto-costmap+json" MUST be the first
part.
The content of the "application/alto-costmap+json" part has the same
format as defined in Section 4.1.3 of [I-D.ietf-alto-multi-cost] with
the following constraints:
o When the path vector cost type is included in "cost type" or
"multi-cost-type", the corresponding cost value MUST be encoded as
a JSONArray of AbstractNetworkElementName.
o If the query sent by the client includes cost type path vector, If the ALTO client includes the path vector cost type in the "cost-
the "vtag" field defined in Section 5.4 has to be included in the type" or "multi-cost-types" field of the input parameter, the
response. And the "query-id" information in "vtag" MUST be response use the same format as defined in Section 4.1.3 of
provided to ALTO clients. [RFC8189], but the corresponding cost value MUST be encoded as a
JSONArray of AbstractNetworkElementName.
6.4. Endpoint Cost Service Extensions 6.2. Endpoint Cost Service Extensions
This document extends the Endpoint Cost Service defined in This document extends the Endpoint Cost Service defined in
Section 4.2 in [I-D.ietf-alto-multi-cost]. Section 4.2 in [RFC8189].
The specifications for "HTTP method" and "uses" are the same as The specifications for "HTTP method" and "uses" are the same as
defined in Section 4.2 in [I-D.ietf-alto-multi-cost]. defined in Section 4.2 in [RFC8189].
6.4.1. Media Type
The path vector extension now enables ALTO clients to receive
multiple objects from the endpoint cost service response.
Specifically, if an ALTO client accepts "multipart/related",
"application/alto-endpointcost+json" and "application/alto-
propmap+json" at the same time, the ALTO server MUST use "multipart/
related" as the media type in the HTTP header.
6.4.2. Capabilities
The same as defined in Section 6.3.2.
6.4.3. Property-map 6.2.1. Capabilities
The same as Section 6.2.3. The same as defined in Section 6.1.1.
6.4.4. Accept Input Parameters 6.2.2. Accept Input Parameters
The ReqEndpointCostMap uses the same format as defined in The ReqEndpointCostMap uses the same format as defined in
Section 4.2.2 of [I-D.ietf-alto-multi-cost], with the following Section 4.2.2 of [RFC8189], with the following constraints:
constraints:
cost-type, multi-cost-types: ALTO clients MUST include the path cost-type, multi-cost-types: ALTO clients MUST include the path
vector cost type, e.g. the one with "ane-path" as cost metric and vector cost type, e.g. the one with "ane-path" as cost metric and
"array" as cost mode, in either "cost-type" or "multi-cost-types" "array" as cost mode, in either "cost-type" or "multi-cost-types"
to activate the path vector extension. to activate the path vector extension.
constraints, or-constraints: If the path vector cost type is constraints, or-constraints: If the path vector cost type is
included in either "cost-type" or "multi-cost-types", ALTO clients included in either "cost-type" or "multi-cost-types", ALTO clients
MUST NOT use it in "constraints" or "or-constraints". Otherwise, MUST NOT use it in "constraints" or "or-constraints". Otherwise,
the ALTO server MUST return an error with error code the ALTO server MUST return an error with error code
"E_INVALID_FIELD_VALUE". "E_INVALID_FIELD_VALUE".
testable-cost-types: The path vector cost type MUST NOT be included testable-cost-types: The path vector cost type MUST NOT be included
in the "testable-cost-types" field. Otherwise, the ALTO server in the "testable-cost-types" field. Otherwise, the ALTO server
MUST return an error with error code "E_INVALID_FIELD_VALUE". MUST return an error with error code "E_INVALID_FIELD_VALUE".
6.4.5. Response 6.2.3. Response
If an ALTO client accepts "multipart/related" as defined in If the ALTO client specifies the path vector cost type in the "cost-
Section 6.4.1, HTTP body of the response MUST consist of two parts type" or "multi-cost-types" field of the input parameter, the
with the media types "application/alto-endpointcost+json" and response use the same format as defined in Section 4.2.3 of
"application/alto-propmap+json" accordingly. Specifically, the part [RFC8189], but the corresponding cost value MUST be encoded as a
with media type "application/alto-endpointcost+json" MUST be the JSONArray of AbstractNetworkElementName.
first part.
The content of the "application/alto-endpointcost+json" part has the 6.3. Multipart Cost Property Service
same format as defined in Section 4.2.3 of [I-D.ietf-alto-multi-cost]
with the following constraints:
o When the path vector cost type is included in "cost type" or This document introduces a new ALTO service called "Multipart Cost
"multi-cost-type", the corresponding cost value MUST be encoded as Property Service", which provides the path vector information and the
a JSONArray of AbstractNetworkElementName. associated ANE property information in the same response.
o If the query sent by the client includes cost type path vector, 6.3.1. Media Type
the "vtag" field defined in Section 5.4 has to be included in the
response. And the "query-id" information in "vtag" MUST be The media type of the Multipart Cost Property service is "multipart/
provided to ALTO clients. related".
6.3.2. HTTP Method
The Multipart Cost Property service is requested using the HTTP POST
method.
6.3.3. Accept Input Parameters
The input parameters of the Multipart Cost Property service MUST be
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-
costmapfilter+json", the request body MUST be the same type as
defined by Section 6.1.2.
o If the media type of the request is "application/alto-
endpointcostparams+json", the request body MUST be the same type
as defined by Section 6.2.2.
The path vector cost type MUST be the only cost type in the input
parameter.
6.3.4. Capabilities
TBD
6.3.5. Uses
The "uses" attribute MUST be an array with at least one resource id.
The first resource id MUST point to a Filtered Cost Map or an
Endpoint Cost Service resource. And the path vector cost type MUST
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
in the first resource. So the ALTO client MUST infer that the
Property Map pointed by the "property-map" field of the first
resource is also a dependent resource.
6.3.6. Response
If an ALTO client sends a request of the media type "application/
alto-costmapfilter+json" and accepts "multipart/related", the HTTP
body of the response MUST consist of two parts with the media types
"application/alto-costmap+json" and "application/alto-propmap+json"
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/
alto-endpointcostparams+json" and accepts "multipart/related", the
HTTP body of the response MUST consist of two parts with the media
types "application/alto-endpointcost+json" and "application/alto-
propmap+json" accordingly. The part with media type "application/
alto-endpointcost+json" MUST be the first part. The content of the
"application/alto-endpointcost+json" part has the same format as
defined in Section 6.2.3.
7. Examples 7. Examples
This section lists a series of examples to proceed the flow This section lists some examples of path vector queries and the
scheduling use case in Section 3. corresponding responses.
7.1. Workflow 7.1. Workflow
This section gives a typical workflow of an ALTO client using the This section gives a typical workflow of an ALTO client using the
path-vector extension. path-vector 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 contains the path vector cost type and get the
resource ID of the dependent abstract network element property resource ID of the dependent abstract network element 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. Send a path-vector request which accepts "multipart/related"
media type following Section 6.2.1, Section 6.3.1 or media type following "application/alto-costmap+json" or
Section 6.4.1. "application/endpointcost+json".
Alternatively, one can replace step 4 with the following:
1. Send a path-vector request which accepts "application/alto-
costmap+json" or "application/alto-endpointcost+json".
2. Find the "query-id" in "vtag" in the response.
3. Query the dependent abstract network element property map with
the query ID and abstract network element names to retrieve the
associated properties.
7.2. Information Resource Directory Example 7.2. 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-delay-availbw" supports
properties "availbw" and "delay", and "propmap-location" supports properties "availbw" and "delay", and "propmap-location" supports
property "location". property "location".
skipping to change at page 18, line 13 skipping to change at page 17, line 9
"uri": "http://alto.exmaple.com/endpointcostmap/multicost", "uri": "http://alto.exmaple.com/endpointcostmap/multicost",
"media-type": "application/alto-endpointcost+json", "media-type": "application/alto-endpointcost+json",
"accepts": "application/alto-endpointcostparams+json", "accepts": "application/alto-endpointcostparams+json",
"capabilities": { "capabilities": {
"cost-constraints": true, "cost-constraints": true,
"cost-type-names": [ "pv", "num-routingcost" ], "cost-type-names": [ "pv", "num-routingcost" ],
"max-cost-types": 2 "max-cost-types": 2
}, },
"property-map": "propmap-availbw" "property-map": "propmap-availbw"
}, },
"propmap-availbw" : { "propmap-availbw-delay" : {
"uri": "http://alto.exmaple.com/propmap/availbw", "uri": "http://alto.exmaple.com/propmap/availbw",
"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": [ "ane" ], "domain-types": [ "ane" ],
"prop-types": [ "delay", "availbw" ] "prop-types": [ "availbw" ]
} }
}, },
"propmap-delay" : { "propmap-location" : {
"uri": "http://alto.exmaple.com/propmap/delay", "uri": "http://alto.exmaple.com/propmap/delay",
"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": [ "ane" ], "domain-types": [ "pid" ],
"prop-types": [ "delay" ] "prop-types": [ "location" ]
} }
} }
} }
} }
7.3. Single Query Example # 1 7.3. Example # 1
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: multipart/related, application/alto-costmap+json,
application/alto-propmap+json, application/alto-error+json application/alto-propmap+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": {
skipping to change at page 19, line 22 skipping to change at page 18, line 17
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": "default-network-map",
"tag": "75ed013b3cb58f896e839582504f622838ce670f" "tag": "75ed013b3cb58f896e839582504f622838ce670f"
} }
], ],
"cost-type": { "cost-mode": "array", "cost-metric": "ane-path" }, "cost-type": {
"cost-mode": "array",
"vtag": { "cost-metric": "ane-path"
"resource-id": "cost-map-pv", },
"tag": "27612897acf278ffu3287c284dd28841da78213",
"query-id": "query1"
}
}, },
"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" ]
} }
} }
} }
skipping to change at page 20, line 5 skipping to change at page 18, line 44
{ {
"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-- --42--
7.4. Single Query Example # 2 7.4. Example # 2
POST /endpointcostmap/multicost HTTP/1.1 POST /endpointcostmap/multicost HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: multipart/related, application/alto-costmap+json, Accept: multipart/related, application/alto-endpointcost+json,
application/alto-propmap+json, application/alto-error+json application/alto-propmap+json, application/alto-error+json
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: application/alto-costmapfilter+json Content-Type: application/alto-endpointcostparams+json
{ {
"multi-cost-types": [ "multi-cost-types": [
{ {
"cost-mode": "array", "cost-mode": "array",
"cost-metric": "ane-path" "cost-metric": "ane-path"
}, },
{ {
"cost-mode": "numerical", "cost-mode": "numerical",
"cost-metric": "routingcost" "cost-metric": "routingcost"
} }
skipping to change at page 20, line 46 skipping to change at page 19, line 36
--example-2 --example-2
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"multi-cost-types": [ "multi-cost-types": [
{"cost-mode": "array", "cost-metric": "ane-path"}, {"cost-mode": "array", "cost-metric": "ane-path"},
{"cost-mode": "numerical", "cost-metric": "routingcost"} {"cost-mode": "numerical", "cost-metric": "routingcost"}
] ]
"vtag": {
"resource-id": "endpoint-multicost-map",
"tag": "47612897acf278ffa3287cb84dd28841da78213",
"query-id": "query2"
}
}, },
"endpoint-cost-map": { "endpoint-cost-map": {
"ipv4:192.0.2.2": { "ipv4:192.0.2.2": {
"ipv4:192.0.2.89": [[ "ane:L001", "ane:L003", "ane:L004" ], 77], "ipv4:192.0.2.89": [[ "ane:L001", "ane:L003", "ane:L004" ], 77],
"ipv4:203.0.113.45": [[ "ane:L001", "ane:L004", "ane:L005" ], 68], "ipv4:203.0.113.45": [[ "ane:L001", "ane:L004", "ane:L005" ], 68],
"ipv6:2001:db8::10": [[ "ane:L001", "ane:L005", "ane:L007" ], 98] "ipv6:2001:db8::10": [[ "ane:L001", "ane:L005", "ane:L007" ], 98]
} }
} }
} }
--example-2 --example-2
skipping to change at page 21, line 28 skipping to change at page 20, line 14
"ane:L001": { "availbw": 50 }, "ane:L001": { "availbw": 50 },
"ane:L003": { "availbw": 48 }, "ane:L003": { "availbw": 48 },
"ane:L004": { "availbw": 55 }, "ane:L004": { "availbw": 55 },
"ane:L005": { "availbw": 60 }, "ane:L005": { "availbw": 60 },
"ane:L007": { "availbw": 35 } "ane:L007": { "availbw": 35 }
} }
} }
--example-2-- --example-2--
7.5. Multiple Queries Example
7.5.1. Endpoint Cost Service Example
POST /endpointcostmap/multicost HTTP/1.1
Host: alto.example.com
Accept: application/alto-costmap+json, application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-costmapfilter+json
{
"multi-cost-types": [
{
"cost-mode": "array",
"cost-metric": "ane-path"
},
{
"cost-mode": "numerical",
"cost-metric": "routingcost"
}
],
"endpoints": {
"srcs": [ "ipv6:2001:db8::10" ],
"dsts": [ "ipv4:192.0.2.3",
"ipv4:203.0.113.56" ]
}
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-endpointcost+json
{
"meta": {
"vtag": {
"resource-id": "endpoint-multicost-map",
"tag": "f7622897bcf278ffu3287c284dd23841da78213",
"query-id": "query3"
},
"multi-cost-types": [
{ "cost-mode": "array", "cost-metric": "ane-path" },
{ "cost-mode": "numerical", "cost-metric": "routingcost"}
]
},
"endpoint-cost-map": {
"ipv6:2001:db8::10": {
"ipv4:192.0.2.3": [ "ane:L001", "ane:L006" ],
"ipv4:203.0.113.56": [ "ane:L001", "ane:L007" ]
}
}
}
7.5.2. Abstract Network Element Property Map Example
POST /propmap/availbw 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
{
"query-id": "query3",
"entities" : [ "ane:L001",
"ane:L006" ],
"properties" : [ "availbw" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-propmap+json
{
"property-map": {
"ane:L001": { "availbw": 25 },
"ane:L006": { "availbw": 40 }
}
}
8. Compatibility 8. Compatibility
8.1. Compatibility with Legacy ALTO Clients/Servers 8.1. Compatibility with Legacy ALTO Clients/Servers
Legacy ALTO clients SHOULD NOT send queries with the path-vector Legacy ALTO clients SHOULD NOT send queries with the path-vector
extension and ALTO servers with this extension SHOULD NOT have any extension and ALTO servers with this extension SHOULD NOT have any
compatibility issue. Legacy ALTO servers do not support cost types compatibility issue. Legacy ALTO servers do not support cost types
with cost mode being "array" and cost metric being "ane-path", so with cost mode being "array" and cost metric being "ane-path", so
they MUST NOT announce the extended cost types in IRD. Thus, ALTO they MUST NOT announce the extended cost types in IRD. Thus, ALTO
clients MUST NOT send queries specified in this extension to legacy clients MUST NOT send queries specified in this extension to base
ALTO servers according to Section 11.3.2.3 [RFC7285]. ALTO servers according to Section 11.3.2.3 [RFC7285].
8.2. Compatibility with Multi-Cost Extensions 8.2. Compatibility with Multi-Cost Extensions
Path Vector is not a testable cost type. Any format of constraints Path Vector is not a testable cost type. Any format of constraints
SHOULD NOT be applied to cost type path-vector in order for multi- SHOULD NOT be applied to cost type path-vector in order for multi-
cost to support the path-vector extension. Specifically, cost to support the path-vector extension. Specifically,
o Cost type path-vector MUST NOT be included in "testable-cost- o Cost type path-vector MUST NOT be included in "testable-cost-
types-names" or "testable-cost-types". types-names" or "testable-cost-types".
skipping to change at page 26, line 8 skipping to change at page 22, line 39
another future extension. another future extension.
11.2. ALTO Cost Metric Registry 11.2. 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 5.1.1 | | ane-path | See Section 5.1.2 |
+-------------+---------------------+ +-------------+---------------------+
Table 2: ALTO Cost Metrics Table 2: ALTO Cost Metrics
11.3. ALTO Entity Domain Registry 11.3. ALTO Network Element Property Type Registry
As proposed in Section 9.2 of [I-D.roome-alto-unified-props], "ALTO
Entity Domain Registry" is requested. Besides, a new domain is to be
registered, listed in Table 3.
+-------------+--------------------------+--------------------------+
| Identifier | Entity Address Encoding | Hierarchy & Inheritance |
+-------------+--------------------------+--------------------------+
| ane | See Section 5.2.2 | None |
+-------------+--------------------------+--------------------------+
Table 3: ALTO Entity Domain
11.4. 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 Entity Domain "ane", listed in Table 3.
+-------------+--------------------------+ +-------------+--------------------------+
| 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 3: ALTO Abstract Network Element Property Types
12. Acknowledgments 12. Acknowledgments
The authors would like to thank discussions with Andreas Voellmy, The authors would like to thank discussions with Randriamasy Sabine,
Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan Andreas Voellmy, Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao
Liu, Xiao Shi, Xin Wang, and Yan Luo. Xiang, Tianyuan Liu, Xiao Shi, Xin Wang, and Yan Luo.
13. References 13. References
13.1. Normative References 13.1. 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, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
<http://www.rfc-editor.org/info/rfc2119>. editor.org/info/rfc2119>.
13.2. Informative References 13.2. 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.
[I-D.clemm-i2rs-yang-network-topo] [I-D.clemm-i2rs-yang-network-topo]
Clemm, A., Medved, J., Tkacik, T., Varga, R., Bahadur, N., Clemm, A., Medved, J., Tkacik, T., Varga, R., Bahadur, N.,
and H. Ananthakrishnan, "A YANG Data Model for Network and H. Ananthakrishnan, "A YANG Data Model for Network
Topologies", draft-clemm-i2rs-yang-network-topo-01 (work Topologies", draft-clemm-i2rs-yang-network-topo-01 (work
in progress), October 2014. in progress), October 2014.
[I-D.gao-alto-fcs]
Gao, K., Zhang, J., Wang, J., Xiang, Q., and Y. Yang,
"ALTO Extension: Flow-based Cost Query", draft-gao-alto-
fcs-01 (work in progress), March 2017.
[I-D.ietf-alto-cost-calendar] [I-D.ietf-alto-cost-calendar]
Randriamasy, S., Yang, Y., Wu, Q., Lingli, D., and N. Randriamasy, S., Yang, Y., Wu, Q., Lingli, D., and N.
Schwan, "ALTO Cost Calendar", draft-ietf-alto-cost- Schwan, "ALTO Cost Calendar", draft-ietf-alto-cost-
calendar-01 (work in progress), February 2017. calendar-01 (work in progress), February 2017.
[I-D.ietf-alto-incr-update-sse] [I-D.ietf-alto-unified-props-new]
Roome, W. and Y. Yang, "ALTO Incremental Updates Using Roome, W. and Y. Yang, "Extensible Property Maps for the
Server-Sent Events (SSE)", draft-ietf-alto-incr-update- ALTO Protocol", draft-ietf-alto-unified-props-new-00 (work
sse-03 (work in progress), September 2016. in progress), July 2017.
[I-D.ietf-alto-multi-cost]
Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
ALTO", draft-ietf-alto-multi-cost-07 (work in progress),
March 2017.
[I-D.lee-alto-app-net-info-exchange] [I-D.lee-alto-app-net-info-exchange]
Lee, Y., Bernstein, G., Choi, T., and D. Dhody, "ALTO Lee, Y., Bernstein, G., Choi, T., and D. Dhody, "ALTO
Extensions to Support Application and Network Resource Extensions to Support Application and Network Resource
Information Exchange for High Bandwidth Applications", Information Exchange for High Bandwidth Applications",
draft-lee-alto-app-net-info-exchange-02 (work in draft-lee-alto-app-net-info-exchange-02 (work in
progress), July 2013. progress), July 2013.
[I-D.roome-alto-unified-props]
Roome, W., "Extensible Property Maps for the ALTO
Protocol", draft-roome-alto-unified-props-01 (work in
progress), July 2016.
[RFC2387] Levinson, E., "The MIME Multipart/Related Content-type", [RFC2387] Levinson, E., "The MIME Multipart/Related Content-type",
RFC 2387, DOI 10.17487/RFC2387, August 1998, RFC 2387, DOI 10.17487/RFC2387, August 1998,
<http://www.rfc-editor.org/info/rfc2387>. <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,
<http://www.rfc-editor.org/info/rfc7285>. <https://www.rfc-editor.org/info/rfc7285>.
[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>.
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
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