draft-ietf-alto-path-vector-05.txt   draft-ietf-alto-path-vector-06.txt 
ALTO WG K. Gao ALTO WG K. Gao
Internet-Draft Tsinghua University Internet-Draft Tsinghua University
Intended status: Standards Track Y. Lee Intended status: Standards Track Y. Lee
Expires: September 12, 2019 Huawei Expires: December 20, 2019 Huawei
S. Randriamasy S. Randriamasy
Nokia Bell Labs Nokia Bell Labs
Y. Yang Y. Yang
Yale University Yale University
J. Zhang J. Zhang
Tongji University Tongji University
March 11, 2019 June 18, 2019
ALTO Extension: Path Vector Cost Type ALTO Extension: Path Vector Cost Type
draft-ietf-alto-path-vector-05 draft-ietf-alto-path-vector-06
Abstract Abstract
The Application-Layer Traffic Optimization (ALTO) protocol [RFC7285] The Application-Layer Traffic Optimization (ALTO) protocol [RFC7285]
has defined cost maps and endpoint cost maps to provide basic network has defined cost maps and endpoint cost maps to provide basic network
information. However, they provide only scalar (numerical or information. However, they provide only scalar (numerical or
ordinal) cost mode values, which are insufficient to satisfy the ordinal) cost mode values, which are insufficient to satisfy the
demands of solving more complex network optimization problems. This demands of solving more complex network optimization problems. This
document introduces an extension to the base ALTO protocol, namely document introduces an extension to the base ALTO protocol, namely
the path-vector extension, which allows ALTO clients to query the path-vector extension, which allows ALTO clients to query
skipping to change at page 1, line 46 skipping to change at page 1, line 46
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.
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This Internet-Draft will expire on September 12, 2019. This Internet-Draft will expire on December 20, 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 Co-Flow Scheduling . . . . . . 5 3. Use Case: Capacity Region for Co-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 Mode to Encode Path Vectors . . . . . . . . . . 7
4.2. New ALTO Entity Domain to Provide ANE Properties . . . . 8 4.2. New ALTO Entity Domain for ANE Properties . . . . . . . . 8
4.3. Extended Cost Map/Endpoint Cost Service for Compound 4.3. Multipart/Related Resource for Consistency . . . . . . . 8
Resources . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Path-Vector Cost Type . . . . . . . . . . . . . . . . . . . . 9
5. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Cost Mode: path-vector . . . . . . . . . . . . . . . . . 10
5.1. Cost Mode: array . . . . . . . . . . . . . . . . . . . . 9 5.2. Cost Metric: Link Maximum Reservable Bandwidth . . . . . 10
5.2. Cost Metric: ane-path . . . . . . . . . . . . . . . . . . 9
5.3. Path Vector Cost Type Semantics . . . . . . . . . . . . . 9
6. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Domain Name . . . . . . . . . . . . . . . . . . . . . . . 10 6.1. Domain Name . . . . . . . . . . . . . . . . . . . . . . . 11
6.2. Domain-Specific Entity Addresses . . . . . . . . . . . . 10 6.2. Domain-Specific Entity Identifier . . . . . . . . . . . . 11
6.3. Hierarchy and Inheritance . . . . . . . . . . . . . . . . 10 6.3. Hierarchy and Inheritance . . . . . . . . . . . . . . . . 11
7. Protocol Extensions for Path Vector . . . . . . . . . . . . . 10 7. Multipart Filtered Cost Map for Path Vector . . . . . . . . . 11
7.1. Filtered Cost Map Extensions . . . . . . . . . . . . . . 11 7.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 11
7.1.1. Accept Input Parameters . . . . . . . . . . . . . . . 11 7.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 11
7.1.2. Capabilities . . . . . . . . . . . . . . . . . . . . 11 7.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 12
7.1.3. Response . . . . . . . . . . . . . . . . . . . . . . 12 7.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 12
7.2. Endpoint Cost Service Extensions . . . . . . . . . . . . 12 7.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2.1. Accept Input Parameters . . . . . . . . . . . . . . . 13 7.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2.2. Capabilities . . . . . . . . . . . . . . . . . . . . 13 8. Multipart Endpoint Cost Service for Path Vector . . . . . . . 13
7.2.3. Response . . . . . . . . . . . . . . . . . . . . . . 13 8.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 13
8. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 13 8.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 13
8.2. Information Resource Directory Example . . . . . . . . . 14 8.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 13
8.3. Example # 1 . . . . . . . . . . . . . . . . . . . . . . . 16 8.5. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.4. Example # 2 . . . . . . . . . . . . . . . . . . . . . . . 18 8.6. Response . . . . . . . . . . . . . . . . . . . . . . . . 14
8.5. Example #3 . . . . . . . . . . . . . . . . . . . . . . . 20 9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 22 9.1. Information Resource Directory Example . . . . . . . . . 14
9.1. Compatibility with Base ALTO Clients/Servers . . . . . . 22 9.2. Example #1 . . . . . . . . . . . . . . . . . . . . . . . 16
9.2. Compatibility with Multi-Cost Extension . . . . . . . . . 23 9.3. Example #2 . . . . . . . . . . . . . . . . . . . . . . . 17
9.3. Compatibility with Incremental Update . . . . . . . . . . 23 9.4. Example for Incremental Update . . . . . . . . . . . . . 19
10. General Discussions . . . . . . . . . . . . . . . . . . . . . 23 10. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 20
10.1. Provide Calendar for Property Map . . . . . . . . . . . 23 10.1. Compatibility with Base ALTO Clients/Servers . . . . . . 20
10.2. Constraint Tests for General Cost Types . . . . . . . . 24 10.2. Compatibility with Multi-Cost Extension . . . . . . . . 21
10.3. General Compound Resources Query . . . . . . . . . . . . 24 10.3. Compatibility with Incremental Update . . . . . . . . . 21
11. Security Considerations . . . . . . . . . . . . . . . . . . . 24 11. General Discussions . . . . . . . . . . . . . . . . . . . . . 21
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 11.1. Provide Calendar for Property Map . . . . . . . . . . . 21
12.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 25 11.2. Constraint Tests for General Cost Types . . . . . . . . 22
12.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 26 11.3. General Multipart Resources Query . . . . . . . . . . . 22
12.3. ALTO Entity Domain Registry . . . . . . . . . . . . . . 26 12. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12.4. ALTO Network Element Property Type Registry . . . . . . 26 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 13.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 23
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 13.2. ALTO Entity Domain Registry . . . . . . . . . . . . . . 23
14.1. Normative References . . . . . . . . . . . . . . . . . . 27 13.3. ALTO Property Type Registry . . . . . . . . . . . . . . 24
14.2. Informative References . . . . . . . . . . . . . . . . . 27 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
15.1. Normative References . . . . . . . . . . . . . . . . . . 24
15.2. Informative References . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
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 maps and endpoint cost information through services such as cost maps and endpoint cost
service. These services use an extreme "single-node" network service. These services use an extreme "single-node" network
abstraction, which represents a whole network as a single node and abstraction, which represents a whole network as a single node, and
hosts as "endpoint groups" directly connected to the node. hosts as "endpoint groups" directly connected to the node.
Although the "single-node" abstraction works well in many settings, Although the "single-node" abstraction works well in many settings,
it lacks the ability to support emerging use cases, such as co-flow it lacks the ability to support emerging use cases, such as co-flow
scheduling for large-scale data analytics. For such a use case, scheduling for large-scale data analytics. For such a use case,
applications require a more powerful network view abstraction beyond applications require a more powerful network view abstraction beyond
the "single-node" abstraction. the "single-node" abstraction.
To support capabilities like co-flow scheduling, this document uses a To support capabilities like co-flow scheduling, this document uses a
"path vector" abstraction to represent more detailed network graph "path vector" abstraction to represent more detailed network graph
information like capacity regions. The path vector abstraction uses information like capacity regions. A path vector is a sequence of
path vectors with abstract network elements to provide network graph abstract network elements (ANEs), and each ANE represents a network
view for applications. A path vector consists of a sequence of device that end-to-end traffic goes through, such as links, switches,
abstract network elements (ANEs) that end-to-end traffic goes middleboxes, and their aggregations. An ANE can have properties such
through. Example ANEs include links, switches, middleboxes, and as "bandwidth", and "delay". Providing such information can help
their aggregations. An ANE can have properties such as "bandwidth", both applications to achieve better application performance and
"delay". Providing such information can help both applications to networks to avoid network congestion.
achieve better application performance and networks to avoid network
congestion.
Providing path vector abstraction using ALTO introduces the following Providing path vector abstraction using ALTO introduces the following
additional requirements (ARs): additional requirements (ARs):
AR-1: The path vector abstraction requires the encoding of array- AR-1: The path vector abstraction requires the encoding of array-
like cost values rather than scalar cost values in cost maps or like cost values rather than scalar cost values in cost maps or
endpoint cost maps. endpoint cost maps.
Specifically, the path vector abstraction requires the Specifically, the path vector abstraction requires the
specification of the sequence of ANEs between sources and specification of the sequence of ANEs between sources and
destinations. Such a sequence, however, cannot be encoded by the destinations. Such a sequence, however, cannot be encoded by the
scalar types (numerical or ordinal) which the base ALTO protocol scalar types (numerical or ordinal) which the base ALTO protocol
supports. supports.
AR-2: The path vector abstraction requires the encoding of the AR-2: The path vector abstraction requires the encoding of the
properties of aforementioned ANEs. properties of aforementioned ANEs.
Specifically, only the sequences of ANEs are not enough for Specifically, only the sequences of ANEs are not enough for
existing use cases. Properties of ANEs such as "bandwidth" and existing use cases. Properties of ANEs such as "bandwidth" and
"delay" are needed by applications to properly construct capacity "delay" are needed by applications to properly construct network
regions. constraints or states.
AR-3: The path vector abstraction requires consistent encoding of AR-3: The path vector abstraction requires consistent encoding of
path vectors (AR-1) and the properties of the elements in a path path vectors (AR-1) and the properties of the ANEs in a path
vector (AR-2). vector (AR-2).
Specifically, path vectors and the properties of abstract network Specifically, path vectors and the properties of ANEs in the
elements in the vectors are dependent. A mechanism to query both vectors are dependent. A mechanism to query both of them
of them consistently is necessary. consistently is necessary.
This document proposes the path vector extension which satisfies This document proposes the path vector extension to the ALTO protocol
these additional requirements to the ALTO protocol. Specifically, to satisfy these additional requirements .
the ALTO protocol encodes the array of ANEs over an end-to-end path
using a new cost type, and conveys the properties of ANEs using Specifically, the extension encodes the array (AR-1) of ANEs over an
unified property map [I-D.ietf-alto-unified-props-new]. We also end-to-end path using a new cost type, and conveys the properties of
provide an optional solution to query separated path vectors and ANEs (AR-2) using unified property map
properties of ANEs in a consistent way. But querying general [I-D.ietf-alto-unified-props-new]. The path vector and ANE
separated resources consistently is not the scope in this document. properties are conveyed in a single message encoded as a multipart/
related message to satisfy AR-3.
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 co-flow scheduling and illustrates the limitations of an example of co-flow scheduling and illustrates the limitations of
the base ALTO protocol in such a use case. Section 4 gives an the base ALTO protocol in such a use case. Section 4 gives an
overview of the path vector extension. Section 5 introduces a new overview of the path vector extension. Section 5 introduces a new
cost type. Section 6 registers a new domain in Domain Registry. cost type. Section 6 registers a new domain in Domain Registry.
Section 7 extends Filtered Cost Map and Endpoint Cost Service to Section 7 and Section 8 define new ALTO resources to support Path
support the compound resource query. Section 8 presents several Vector query by using the request format of Filtered Cost Map and
examples. Section 9 and Section 10 discusses compatibility issues Endpoint Cost Service. Section 9 presents several examples.
with other existing ALTO extensions and design decisions. Section 11 Section 10 and Section 11 discusses compatibility issues with other
and Section 12 review the security and IANA considerations. existing ALTO extensions and design decisions. Section 12 and
Section 13 review the security and IANA considerations.
2. Terminology 2. Terminology
Besides the terms defined in [RFC7285] 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, Path Vector. following additional terms: Abstract Network Element 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), etc. An links, middleboxes, virtualized network function (VNF), etc. An
abstract network element has two types of attributes: a name and a abstract network element has two types of attributes: a name and a
set of properties. set of properties.
o Path Vector: A path vector is an array of ANEs. It presents an o Path Vector: A path vector is an array of ANEs. It presents an
abstract network path between source/destination points such as abstract network path between source/destination points such as
PIDs or endpoints. PIDs or endpoints.
3. Use Case: Capacity Region for Co-Flow Scheduling 3. Use Case: Capacity Region for Co-Flow Scheduling
Assume that an application has control over a set of flows, which may Assume that an application has control over a set of flows, which may
go through shared links or switches and share a bottleneck. The go through shared links or switches and share a bottleneck. The
application hopes to schedule the traffic among multiple flows to get application hopes to schedule the traffic among multiple flows to get
better performance. The capacity region information for those flows better performance. The capacity region information for those flows
will benefit the scheduling. However, existing cost maps can not will benefit the scheduling. However, existing cost maps cannot
reveal such information. 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 all links are 100 Mbps.
and the bandwidth of the rest links are 100 Mbps.
+------+ +------+
| | | |
--+ sw6 +-- --+ sw6 +--
/ | | \ / | | \
PID1 +-----+ / +------+ \ +-----+ PID2 PID1 +-----+ / +------+ \ +-----+ PID2
eh1__| |_ / \ ____| |__eh2 eh1__| |_ / \ ____| |__eh2
| sw1 | \ +--|---+ +---|--+ / | sw2 | | sw1 | \ +--|---+ +---|--+ / | sw2 |
+-----+ \ | | | |/ +-----+ +-----+ \ | | | |/ +-----+
\_| sw5 +---------+ sw7 | \_| sw5 +---------+ sw7 |
skipping to change at page 6, line 40 skipping to change at page 6, line 40
{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 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 eh3 -> 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 eh3 -> 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 eh3 -> eh4 uses path eh3 -> sw3 -> sw5 ->
sw7 -> sw4 -> eh4, then the application will obtain 150 Mbps at sw7 -> sw4 -> eh4, then the application will obtain 200 Mbps.
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 eh3 -> eh4 uses the path eh3 -> sw3 -> sw5 -> sw7
-> sw4 -> eh4, then the application will obtain only 100 Mbps at -> sw4 -> eh4, then the application will obtain only 100 Mbps due
most. to the shared link from sw5 to sw7.
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 propose a solution The path vector extension defined in this document provides a
to provide these details. solution to address the preceding issue.
See [I-D.bernstein-alto-topo] for a more comprehensive survey of use See [I-D.bernstein-alto-topo] for a more comprehensive survey of use
cases where 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 cost map vector extension. It assumes that the readers are familiar with cost
and endpoint cost service defined in [RFC7285]. The path vector map and endpoint cost service defined in [RFC7285]. The path vector
extension also requires the support of Filtered Property Map defined extension also requires the support of Filtered Property Map defined
in [I-D.ietf-alto-unified-props-new]. in [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 ALTO entity domain new cost mode to encode path vectors in a cost map or an endpoint
for unified property extension [I-D.ietf-alto-unified-props-new] to cost map; (2) a new ALTO entity domain to enable ANE property
encode properties of ANEs; and (3) an extension to the cost map and encoding using the unified property extension
endpoint cost resource to provide path vectors and properties of ANEs [I-D.ietf-alto-unified-props-new]; and (3) a generic mechanism to put
in a single response. multiple ALTO information objects in a single response to enforce
consistency, to preserve modularity and to avoid complex linking of
multiple responses.
4.1. New Cost Type to Encode Path Vectors 4.1. New Cost Mode to Encode Path Vectors
Existing cost types defined in [RFC7285] allow only scalar cost Existing cost modes defined in [RFC7285] allow only scalar cost
values. However, the "path vector" abstraction requires to convey values. However, the "path vector" abstraction requires to convey
vector format information. To achieve this requirement, this vector format information (AR-1). To fulfill this requirement, this
document defines a new cost mode to enable the cost value to carry an document defines a new "cost-mode" named path vector to indicate that
array of elements, and a new cost metric to take names of ANEs as the cost value is an array of ANEs. A path vector abstraction should
elements in the array. We call such an array of ANEs a path vector. be computed for a specific performance metric, and this is achieved
In this way, the cost map and endpoint cost service can convey the using the existing "cost-metric" component of cost type. The details
path vector to represent the routing information. Detailed of the new "cost-mode" is given in Section 5.
information and specifications are given in Section 5.1 and
Section 5.2.
4.2. New ALTO Entity Domain to Provide ANE Properties 4.2. New ALTO Entity Domain for ANE Properties
The path vector can only represent the route between the source and A path vector of ANEs contains only the abstracted routing elements
the destination. Although the application can find the shared ANEs between a source and a destination. Hence, an application can find
among different paths, it is not enough for most use cases, which shared ANEs of different source-destination pairs but cannot know the
requires the bandwidth or delay information of the ANEs. So this shared ANEs' properties. For the capacity region use case in
document adopts the property map defined in Section 3, knowing that eh1->eh2 and eh3->eh4 share ANEs but not the
[I-D.ietf-alto-unified-props-new] to provide the general properties available bandwidth of the shared ANEs, is not enough.
of ANEs. The document registers a new entity domain called "ane" to
represent the ANE. The address of the ANE entity is just the ANE
name used by the path vector. By requesting the property map of
entities in the "ane" domain, the client can retrieve the properties
of ANEs in path vectors.
4.3. Extended Cost Map/Endpoint Cost Service for Compound Resources To encode ANE properties like the available bandwidth in a path
vector query response, this document uses the unified property
extension defined in [I-D.ietf-alto-unified-props-new].
Specifically, for each path vector query, the ALTO server generates a
property map associated to the (endpoint) cost map as follows:
Providing the path vector information and the ANE properties by o a dynamic entity domain of an entity domain type "ane" is
separated resources have several known benefits: (1) can be better generated to contain the generated ANEs. Each ANE has the same
compatible with the base ALTO protocol; (2) can make different unique identifier in the path vectors and in the dynamic entity
property map resources reuse the same cost map or endpoint cost domain;
resource. However, it conducts two issues:
o Efficiency: The separated resources will require the ALTO client o each entity in this dynamic entity domain has the property defined
to invoke multiple requests/responses to collect all needed by the "cost-metric" that generated the ANEs in the query.
information. It increases the communication overhead.
o Consistency: The path vectors and properties of ANEs are Detailed information and specifications are given in Section 6.
correlated. So querying them one by one may conduct consistency
issue. Once the path vector changes during the client requests
the ANE properties, the ANE properties may be inconsistent with
the previous path vector.
To solve these issues, this document introduces an extension to cost 4.3. Multipart/Related Resource for Consistency
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.
These issues may exist in all general cases for querying separated Path vectors and the property map containing the ANEs are two
ALTO information resources. But solving this general problem is not different types of objects, but they require strong consistency. One
in the scope of this document. approach to achieving strong consistency is to define a new media
type to contain both objects, but this violates modular design.
5. Cost Type Another approach is to provide the objects in two different
information resources. Thus, an ALTO client needs to make separate
queries to get the information of related services. This may cause a
data synchronization problem between two queries. Also, as the
generation of ANE is dynamic, an ALTO server must cache the results
of a query before a client fully retrieves all related resources,
which hurts the scalability and security of an ALTO server.
This document extends the cost types defined in Section 6.1 of This document uses standard-conforming usage of "multipart/related"
[RFC7285] by introducing a new cost mode "array" and a new cost media type defined in [RFC2387] to elegantly solve the problem.
metric "ane-path". In the rest content, this document uses "path-
vector" to indicate the combination cost type of the cost mode
"array" and the cost metric "ane-path".
5.1. Cost Mode: array Specifically, using "multipart/related" needs to address two issues:
This document extends the CostMode defined in Section 10.5 of o ALTO uses media type to indicate the type of an entry in the
[RFC7285] with a new cost mode: "array". This cost mode indicates information resource directory (IRD) (e.g., "application/alto-
that every cost value in a cost map represents an array rather than a costmap+json" for cost map and "application/alto-
simple value. The values are arrays of JSONValue. The specific type endpointcostmap+json" for endpoint cost map). Simply putting
of each element in the array depends on the cost metric. "multipart/related" as the media type, however, makes it
impossible for an ALTO client to identify the type of service
provided by related entries.
5.2. Cost Metric: ane-path o The ALTO SSE extension (see [I-D.ietf-alto-incr-update-sse])
depends on resource-id to identify push updates, but resource-id
is provided only in IRD and hence each entry in the IRD has only
one resource-id.
This document specifies a new cost metric: "ane-path". This cost This design addresses the two issues as follows:
metric indicates that the cost value is a list of ANEs which the path
from a source to a destination goes across. The values are arrays of
ANE names which are defined in Section 6.2.
The cost metric "ane-path" SHOULD NOT be used when the cost mode is o To address the first issue, the multipart/related media type
not "array" unless it is explicitly specified by a future extension. includes the type parameter to allow type indication of the root
If an ALTO client send queries with the cost metric "ane-path" and a object. For a cost map service, the "media-type" will be
non "array" cost mode, the ALTO server SHOULD return an error with "multipart/related" with the parameter "type=application/alto-
the error code "E_INVALID_FIELD_VALUE"; If an ALTO server declares costmap+json"; for an endpoint cost map service, the parameter
the support of a cost type with the cost metric "ane-path" and a non will be "type=application/alto-endpointcostmap+json". This design
"array" cost mode, the ALTO client SHOULD assume such a cost type is is highly extensible. The entries can still use "application/
invalid and ignore it. alto-costmapfilter+json" or "application/alto-
endpointcostparams+json" as the accept input parameters, and hence
an ALTO client still sends the filtered cost map request or
endpoint cost service request. The ALTO server sends the response
as a "multipart/related" message. The body of the response
includes two parts: the first one is of the media type specified
by the "type" parameter; the second one is a property map
associated to the first map.
5.3. Path Vector Cost Type Semantics o To address the second issue, each part of the "multipart/related"
response message has the MIME part header information including
"Content-Type" and "Resource-Id". An ALTO server MAY generate
incremental updates (see [I-D.ietf-alto-incr-update-sse]) for each
part separately using the "Resource-Id" header.
The new cost type follows the convention of the cost types in the By applying the design above, for each path vector query, an ALTO
base ALTO protocol. Table 1 lists some of the current defined cost server returns the path vectors and the associated property map
types and their semantics. modularly and consistently. An ALTO server can reuse the data models
of the existing information resources. And an ALTO client can
subscribe to the incremental updates for the dynamic generated
information resources without any changes, if th ALTO server provides
incremental updates for them.
+------------+--------------+---------------------------------------+ 5. Path-Vector Cost Type
| Cost Mode | Cost Metric | Semantics |
+------------+--------------+---------------------------------------+
| numerical | routingcost | a number representing the routing |
| | | 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 |
| array | ane-path | a list representing the ane path |
+------------+--------------+---------------------------------------+
Table 1: Cost Types and Their Semantics This document extends the cost types defined in Section 6.1 of
[RFC7285] by introducing a new cost mode "path-vector". In the rest
of the document, we use "path-vector" to indicate the cost type with
the cost-mode "path-vector" for short.
The "routingcost" and "hopcount" can encoded in "numerical" or 5.1. Cost Mode: path-vector
"ordinal", however, the cost metric "ane-path" can only be applied to
the cost mode "array" defined in this document to convey path vector This document extends the CostMode defined in Section 10.5 of
information. The cost metric "ane-path" can not be used in [RFC7285] with a new cost mode: "path-vector". This cost mode
"numerical" or "ordinal" unless it is defined in future extensions. indicates that every cost value in a cost map represents an array of
If the ALTO server declares that it support cost type with cost ANEs which are defined in Section 6.2, rather than a JSON number or a
metric being "ane-path" and cost mode not being "array", the ALTO ranking order.
client SHOULD ignore them.
The ANEs computed by the ALTO server associate to the cost metric for
the "path-vector" cost mode. This document re-defines some cost
metrics for "path-vector", which are motivated by the co-flow
scheduling use case. The ALTO client SHOULD ignore the "path-vector"
cost mode with any other cost metrics, unless the future documents
define other cost metrics or specify the semantics of existing cost
metrics for "path-vector" cost mode for some additional requirements.
5.2. Cost Metric: Link Maximum Reservable Bandwidth
This document uses the same metric name, units of measurement and
measurement point(s) with potential measurement domain defined by
section 4.1 of [I-D.ietf-alto-performance-metrics], but specifies
different metric description and method of measurement or calculation
for "path-vector" cost mode only.
Metric Description: When used with "path-vector" cost mode, it is to
specify the path vector computed by using the spatial and temporal
maximum reservable bandwidth over each network link. The value of
the maximum reservable bandwidth of each ANE in the path vector is
specified in the associated property map.
Method of Measurement or Calculation: The value of Maximum
Reservable Bandwidth is the bandwidth measured between two
directly connected IS-IS neighbors, OSPF neighbors or BGP
neighbors. The associated ANEs are computed by some algorithm
which can guarantee the equivalent Maximum Reservable Bandwidth
constraints.
6. ANE Domain 6. ANE Domain
This document specifies a new ALTO entity domain called "ane" in This document specifies a new ALTO entity domain called "ane" in
addition to the ones in [I-D.ietf-alto-unified-props-new]. The ANE 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 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 entity in ANE domain is often used in the path vector by cost maps or
endpoint cost resources. Accordingly, the ANE domain always depends endpoint cost resources. Accordingly, the ANE domain always depends
on a cost map or an endpoint cost map. on a cost map or an endpoint cost map.
6.1. Domain Name 6.1. Domain Name
ane ane
6.2. Domain-Specific Entity Addresses 6.2. Domain-Specific Entity Identifier
The entity address of ane domain is encoded as a JSON string. The The entity identifier 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.
To simplify the description, we use "ANE name" to indicate the To simplify the description, we use "ANE name" to indicate the
address of an entity in ANE domain in this document. identifier of an entity in ANE domain in this document.
The ANE name is usually unrelated to the physical device information. The ANE name is usually unrelated to the physical device information.
It is usually generated by the ALTO server on demand and used to It is usually generated by the ALTO server on demand and used to
distinguish from other ANEs in its dependent cost map or endpoint distinguish from other ANEs in its dependent cost map or endpoint
cost map. cost map.
6.3. Hierarchy and Inheritance 6.3. Hierarchy and Inheritance
There is no hierarchy or inheritance for properties associated with There is no hierarchy or inheritance for properties associated with
ANEs. ANEs.
7. Protocol Extensions for Path Vector 7. Multipart Filtered Cost Map for Path Vector
To make the ALTO client query the path vectors and properties of ANEs This document introduces a new ALTO resource called Multipart
efficiently and consistently, this document extends the Filtered Cost Filtered Cost Map resource, which allows an ALTO server to provide
Map and Endpoint Cost Service. other ALTO resources associated to the Cost Map resource in the same
response.
7.1. Filtered Cost Map Extensions 7.1. Media Type
This document extends Filtered Cost Map, as defined in Section 11.3.2 The media type of the Multipart Filtered Cost Map Resource is
of [RFC7285], by adding new input parameters and capabilities, and by "multipart/related;type=application/alto-costmap+json".
augmenting the property map into the data entry of the response.
The "media type", "HTTP method", and "uses" specifications (described 7.2. HTTP Method
in Sections 11.3.2.1, 11.3.2.2, and 11.3.2.5 of [RFC7285],
respectively) remain the same.
7.1.1. Accept Input Parameters The Multipart Filtered Cost Map is requested using the HTTP POST
method.
The ReqFilteredCostMap object in Section 11.3.2.3 of [RFC7285] is 7.3. Accept Input Parameters
extended as follows:
object { The input parameters of the Multipart Filtered Cost Map MUST be
[PropertyName compound-properties<1..*>;] encoded as a JSON object in the body of an HTTP POST request. The
} ReqPVFilteredCostMap : ReqFilteredCostMap; media type of the request MUST be one of "application/alto-
costmapfilter+json". The format of the request body MUST be the same
type as defined by section 11.3.2.3 of [RFC7285].
compound-properties: If the capability "allow-compound-response" is 7.4. Capabilities
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.
7.1.2. Capabilities The Multipart Filtered Cost Map resource uses the same capabilities
as defined by section 11.3.2.4 of [RFC7285]. But the "cost-type-
names" field SHOULD only includes cost types in "path-vector" cost
mode. Otherwise, the ALTO client SHOULD ignore a cost type in other
cost mode, unless additional documents define the specification of it
for the Multipart Filtered Cost Map resource.
The Filtered Cost Map capabilities are extended with two new members: 7.5. Uses
o dependent-property-map The resource ID of the network map based on which the PIDs in the
returned cost map will be defined.
o allow-compound-response 7.6. Response
The capability "dependent-property-map" indicates which property map The response MUST indicate an error, using ALTO protocol error
this resource depends on, and the capability "allow-compound- handling, as defined in Section 8.5 of [RFC7285], if the request is
response" indicates whether the ALTO server supports the resource to invalid.
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:
object { The response to a valid request MUST be a "multipart/related" message
[ResourceID dependent-property-map;] as defined by [RFC2387]. The body consists of two parts:
[JSONBool allow-compound-response;]
} PVFCMCapabilities : FilteredCostMapCapabilities;
dependent-property-map: This field MUST be specified when the "cost- o the first part MUST include "Resource-Id" and "Content-Type" in
type-names" includes a cost type name indicating a "ane-path" its header. The value of "Resource-Id" MUST be prefixed by the
metric. Its value MUST be a resource id indicating a property map resource id of the Multipart Filtered Cost Map appended by a "."
including "ane" domain. If not, the ALTO client SHOULD consider character. The body of this part MUST be a JSON object with the
this resource is invalid. same format as defined in Section 11.2.3.6 of [RFC7285]; The JSON
object MUST include the "vtag" field in the "meta" field, which
provides the version tag of the returned cost map. The resource
id of the version tag MUST be as same as the value of the
"Resource-Id" header. The "meta" field MUST also include the
"dependent-vtags" field, whose value is a single-element array to
indicate the version tag of the network map used, where the
network map is specified in the "uses" attribute of the Multipart
Cost Map resource in IRD.
allow-compound-response: If present, the true value means the ALTO o the second part MUST also include "Resource-Id" and "Content-Type"
client can request the resource to augment its dependent property in its header. The value of "Resource-Id" MUST be prefixed by the
map into the response automatically; the false value means the resource id of the Multipart Filtered Cost Map appended by a "."
ALTO client cannot request the compound response. If omitted, the character. The body of this part MUST be a JSON object with the
default value is false; same format as defined in Section 4.6 of
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include
the "dependent-vtags" field in the "meta" field. The value of the
"dependent-vtags" field MUST be an array with a single VersionTag
object as defined by section 10.3 of [RFC7285]. The "resource-id"
of this VersionTag MUST be the value of "Resource-Id" header of
the first part. The "tag" of this VersionTag MUST be the "tag" of
"vtag" of the first part body.
To be noticed that the capability "cost-constraints" is unexpected 8. Multipart Endpoint Cost Service for Path Vector
for the "array" cost mode. The syntax and semantics of constraint
tests on the "array" cost mode depends on the implementation and can
be defined in the future documents. But it is not in the scope of
this document.
7.1.3. Response This document introduces a new ALTO resource called Multipart
Endpoint Cost resource, which allows an ALTO server to provide other
ALTO resources associated to the Endpoint Cost resource in the same
response.
If the ALTO client specifies the "cost-type" input parameter with 8.1. Media Type
"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.
If the ALTO client specifies the "compound-properties" input The media type of the Multipart Endpoint Cost Resource is
parameter which is accepted by the ALTO server, the response MUST "multipart/related;type=application/alto-endpointcostmap+json".
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.
7.2. Endpoint Cost Service Extensions 8.2. HTTP Method
This document extends the Endpoint Cost Service, as defined in The Multipart Endpoint Cost resource is requested using the HTTP POST
Section 11.5.1 of [RFC7285], by adding new input parameters and method.
capabilities and by augmenting the property map into the data entry
of the response.
The media type, HTTP method, and "uses" specifications (described in 8.3. Accept Input Parameters
Sections 11.5.1.1, 11.5.1.2, and 11.5.1.5 of [RFC7285], respectively)
are unchanged.
7.2.1. Accept Input Parameters The input parameters of the Multipart Endpoint Cost resource MUST be
encoded as a JSON object in the body of an HTTP POST request. The
media type of the request MUST be one of "application/alto-
endpointcostparams+json". The format of the request body MUST be the
same type as defined by section 11.5.1.3 of [RFC7285].
The ReqEndpointCostMap object in Section 11.5.1.3 of [RFC7285] is 8.4. Capabilities
extended as follows:
object { The Multipart Endpoint Cost resource uses the same capabilities as
[PropertyName compound-properties<1..*>;] defined by section 11.3.2.4 of [RFC7285]. But the "cost-type-names"
} ReqPVEndpointCostMap : ReqEndpointCostMap; field SHOULD only includes cost types in "path-vector" cost mode.
Otherwise, the ALTO client SHOULD ignore a cost type in other cost
mode, unless additional documents define the specification of it for
the Multipart Endpoint Cost resource.
The "compound-properties" has the same interpretation as defined in 8.5. Uses
Section 7.1.1.
7.2.2. Capabilities The Multipart Endpoint Cost resource MUST NOT specify the "uses"
attribute.
The extensions to the Endpoint Cost Service capabilities are 8.6. Response
identical to the extensions to the Filtered Cost Map (see
Section 7.1.2).
7.2.3. Response The response MUST indicate an error, using ALTO protocol error
handling, as defined in Section 8.5 of [RFC7285], if the request is
invalid.
If the ALTO client specifies the "cost-type" input parameter with The response to a valid request MUST be a "multipart/related" message
"ane-path" metric, the response MUST include the "meta" field with as defined by [RFC2387]. The body consists of two parts:
the "dependent-vtags" in it, and the "dependent-vtags" field MUST
include the version tag of its dependent property map.
If the ALTO client specifies the "compound-properties" input o the first part MUST include "Resource-Id" and "Content-Type" in
parameter which is accepted by the ALTO server, the response MUST its header. The value of "Resource-Id" MUST be prefixed by the
include a "property-map" field following the "endpoint-cost-map" resource id of the Multipart Filtered Cost Map appended by a "."
field, and its value MUST be a PropertyMapData object. This character (U+002E). The body of this part MUST be a JSON object
PropertyMapData object MUST be equivalent to the result when query with the same format as defined in Section 11.5.1.6 of [RFC7285];
the dependent property map resource using the following request: the The JSON object MUST include the "vtag" field in the "meta" field,
"entities" field includes all the ANE names appearing in the cost which provides the version tag of the returned endpoint cost map.
values of the "endpoint-cost-map" field, the "properties" field has The resource id of the version tag MUST be as same as the value of
the same value as the "compound-properties" field does. The the "Resource-Id" header.
properties shown in the "compound-properties" input parameter but are
not supported by the dependent property map SHOULD be omitted from
the response.
8. Examples o the second part MUST also include "Resource-Id" and "Content-Type"
in its header. The value of "Resource-Id" MUST be prefixed by the
resource id of the Multipart Filtered Cost Map appended by a "."
character (U+002E). The body of this part MUST be a JSON object
with the same format as defined in Section 4.6 of
[I-D.ietf-alto-unified-props-new]. The JSON object MUST include
the "dependent-vtags" field in the "meta" field. The value of the
"dependent-vtags" field MUST be an array with a single VersionTag
object as defined by section 10.3 of [RFC7285]. The "resource-id"
of this VersionTag MUST be the value of "Resource-Id" header of
the first part. The "tag" of this VersionTag MUST be the "tag" of
"vtag" of the first part body.
9. 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.
8.1. Workflow 9.1. Information Resource Directory Example
This section gives a typical workflow of how an ALTO client query
path vectors using the extension.
1. Send a GET request for the whole Information Resource Directory.
2. Look for the resource of the (Filtered) Cost Map/Endpoint Cost
Service which supports the "ane-path" cost metric and get the
resource ID of the dependent property map.
3. Check whether the capabilities of the property map includes the
desired "prop-types".
4. Check whether the (Filtered) Cost Map/Endpoint Cost Service
allows the compound response.
5. 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.
6. 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, the "cost-map-pv" information resource provides a Multipart
cost extension but support the path-vector extension, "endpoint- Cost Map resource for path-vector; the "endpoint-cost-pv" information
multicost-map" supports both multi-cost extension and path-vector resource provides a MultipartEndpoint Cost resource for path-vector.
extension. Filtered Property Map "propmap-availbw-delay" supports
properties "availbw" and "delay". Both of them support the Maximum Reservable Bandwidth ("maxresbw")
cost metric in "path-vector" cost mode.
{ {
"meta": { "meta": {
"cost-types": { "cost-types": {
"path-vector": { "pv-maxresbw": {
"cost-mode": "array", "cost-mode": "path-vector",
"cost-metric": "ane-path" "cost-metric": "maxresbw"
},
"num-routingcost": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
},
"num-hopcount": {
"cost-mode": "numerical",
"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"
}, },
"my-default-cost-map": {
"uri": "http://alto.example.com/costmap/pv",
"media-type": "application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json",
"capabilities": {
"cost-type-names": [ "num-hopcount",
"num-routingcost" ]
},
"uses": [ "my-default-networkmap" ]
},
"cost-map-pv": { "cost-map-pv": {
"uri": "http://alto.example.com/costmap/pv", "uri": "http://alto.example.com/costmap/pv",
"media-type": "application/alto-costmap+json", "media-type": `multipart/related;
type=application/alto-costmap+json`,
"accepts": "application/alto-costmapfilter+json", "accepts": "application/alto-costmapfilter+json",
"capabilities": { "capabilities": {
"cost-type-names": [ "path-vector" ], "cost-type-names": [ "pv-maxresbw" ]
"dependent-property-map": "propmap-availbw-delay"
}, },
"uses": [ "my-default-networkmap" ] "uses": [ "my-default-networkmap" ]
}, },
"endpoint-cost-pv": { "endpoint-cost-pv": {
"uri": "http://alto.exmaple.com/endpointcost/pv", "uri": "http://alto.exmaple.com/endpointcost/pv",
"media-type": "application/alto-endpointcost+json", "media-type": `multipart/related;
type=application/alto-endpointcost+json`,
"accepts": "application/alto-endpointcostparams+json", "accepts": "application/alto-endpointcostparams+json",
"capabilities": { "capabilities": {
"cost-type-names": [ "path-vector" ], "cost-type-names": [ "pv-maxresbw" ]
"dependent-property-map": "propmap-availbw-delay",
"allow-compound-response": true
} }
}, },
"invalid-cost-map" : { "update-pv": {
"uri": "http://alto.example.com/costmap/invalid", "uri": "http://alto.example.com/updates/pv",
"media-type": "application/alto-costmap+json", "media-type": "text/event-stream",
"accepts": "application/alto-costmapfilter+json", "uses": [ "endpoint-cost-pv" ],
"capabilities": { "accepts": "application/alto-updatestreamparams+json",
"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",
"accepts": "application/alto-propmapparams+json",
"capabilities": { "capabilities": {
"domain-types": [ "ane" ], "support-stream-control": true
"prop-types": [ "availbw", "delay" ] }
},
"uses": [ "cost-map-pv", "endpoint-cost-pv" ]
} }
} }
} }
8.3. Example # 1 9.2. Example #1
Query filtered cost map to get the path vectors. 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: application/alto-costmap+json, Accept: multipart/related;
type=application/alto-costmap+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": "path-vector",
"cost-metric": "ane-path" "cost-metric": "maxresbw"
}, },
"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=example-1;
start=cost-map-pv.costmap
type=application/alto-costmap+json
--example-1
Resource-Id: cost-map-pv.costmap
Content-Type: application/alto-costmap+json Content-Type: application/alto-costmap+json
{ {
"meta": { "meta": {
"vtag": {
"resource-id": "cost-map-pv.costmap",
"tag": "d827f484cb66ce6df6b5077cb8562b0a"
},
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "my-default-networkmap", "resource-id": "my-default-networkmap",
"tag": "75ed013b3cb58f896e839582504f622838ce670f" "tag": "75ed013b3cb58f896e839582504f6228"
} }
], ],
"cost-type": { "cost-type": {
"cost-mode": "array", "cost-mode": "path-vector",
"cost-metric": "ane-path" "cost-metric": "maxresbw"
} }
}, },
"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" ]
} }
} }
} }
--example-1
Then query the properties of ANEs in path vectors. Resource-Id: cost-map-pv.propmap
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": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "cost-map-pv", "resource-id": "cost-map-pv.costmap",
"tag": "a7d57e120ab63124e3c9a82f7a54bc120fc96216" "tag": "d827f484cb66ce6df6b5077cb8562b0a"
} }
] ]
}, },
"property-map": { "property-map": {
"ane:L001": { "delay": 46}, "ane:L001": { "maxresbw": 100000000},
"ane:L003": { "delay": 50}, "ane:L003": { "maxresbw": 150000000},
"ane:L004": { "delay": 70} "ane:L004": { "maxresbw": 50000000}
} }
} }
8.4. Example # 2 9.3. Example #2
POST /endpointcost/pv HTTP/1.1 POST /endpointcost/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: application/alto-endpointcost+json, Accept: multipart/related;
type=application/alto-endpointcost+json,
application/alto-error+json application/alto-error+json
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json Content-Type: application/alto-endpointcostparams+json
{ {
"multi-cost-types": [ "cost-type": {
{ "cost-mode": "path-vector",
"cost-mode": "array", "cost-metric": "maxresbw"
"cost-metric": "ane-path" },
},
{
"cost-mode": "numerical",
"cost-metric": "routingcost"
}
],
"endpoints": { "endpoints": {
"srcs": [ "ipv4:192.0.2.2" ], "srcs": [ "ipv4:192.0.2.2" ],
"dsts": [ "ipv4:192.0.2.89", "dsts": [ "ipv4:192.0.2.89",
"ipv4:203.0.113.45", "ipv4:203.0.113.45",
"ipv6:2001:db8::10" ] "ipv6:2001:db8::10" ]
} }
} }
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: multipart/related; boundary=example-2;
start=endpoint-cost-pv.ecs
type=application/alto-endpointcost+json
--example-2
Resource-Id: endpoint-cost-pv.ecs
Content-Type: application/alto-endpointcost+json Content-Type: application/alto-endpointcost+json
{ {
"meta": { "meta": {
"cost-type": [ "vtags": {
{"cost-mode": "array", "cost-metric": "ane-path"} "resource-id": "endpoint-cost-pv.ecs",
] "tag": "bb6bb72eafe8f9bdc4f335c7ed3b10822a391cef"
},
"cost-type": {
"cost-mode": "path-vector",
"cost-metric": "maxresbw"
}
}, },
"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", "ipv4:192.0.2.89": [ "ane:L001", "ane:L003",
"ane:L004" ], "ane:L004" ],
"ipv4:203.0.113.45": [ "ane:L001", "ane:L004", "ipv4:203.0.113.45": [ "ane:L001", "ane:L004",
"ane:L005" ], "ane:L005" ],
"ipv6:2001:db8::10": [ "ane:L001", "ane:L005", "ipv6:2001:db8::10": [ "ane:L001", "ane:L005",
"ane:L007" ] "ane:L007" ]
} }
} }
} }
--example-2
POST /endpointcost/pv HTTP/1.1 Resource-Id: endpoint-cost-pv.propmap
Host: alto.example.com
Accept: application/alto-endpointcost+json,
application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{
"entities": [ "ane:L001", "ane:L003", "ane:L004",
"ane:L005", "ane:L007" ],
"properties": [ "availbw" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-propmap+json Content-Type: application/alto-propmap+json
{ {
"meta": { "meta": {
"dependent-vtags": [ "dependent-vtags": [
{ {
"resource-id": "endpoint-cost-pv", "resource-id": "endpoint-cost-pv.ecs",
"tag": "12c0889c3c0892bb67df561ed16d93f5d1fa75cf" "tag": "bb6bb72eafe8f9bdc4f335c7ed3b10822a391cef"
} }
] ]
}, },
"property-map": { "property-map": {
"ane:L001": { "availbw": 50 }, "ane:L001": { "maxresbw": 50000000 },
"ane:L003": { "availbw": 48 }, "ane:L003": { "maxresbw": 48000000 },
"ane:L004": { "availbw": 55 }, "ane:L004": { "maxresbw": 55000000 },
"ane:L005": { "availbw": 60 }, "ane:L005": { "maxresbw": 60000000 },
"ane:L007": { "availbw": 35 } "ane:L007": { "maxresbw": 35000000 }
} }
} }
8.5. Example #3 9.4. Example for Incremental Update
POST /endpointcost/pv HTTP/1.1
In this example, an ALTO client subscribe the incremental update for
the Multipart Endpoint Cost resource "endpoint-cost-pv".
POST /updates/pv HTTP/1.1
Host: alto.example.com Host: alto.example.com
Accept: application/alto-endpointcost+json, Accept: text/event-stream
application/alto-error+json Content-Type: application/alto-updatestreamparams+json
Content-Length: [TBD] Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{ {
"multi-cost-types": [ "add": {
{ "ecspvsub1": {
"cost-mode": "array", "resource-id": "endpoint-cost-pv",
"cost-metric": "ane-path" "input": <ecs-input>
},
{
"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" ]
} }
Based on the server process defined in
[I-D.ietf-alto-incr-update-sse], the ALTO server will send the
control-uri first using Server-Sent Event (SSE), and follow the full
response of the multipart message.
HTTP/1.1 200 OK HTTP/1.1 200 OK
Content-Length: [TBD] Connection: keep-alive
Content-Type: application/alto-endpointcost+json Content-Type: text/event-stream
{ event: application/alto-updatestreamcontrol+json
"meta": { data: {"control-uri": "http://alto.example.com/updates/streams/1414"}
"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 }
}
}
9. Compatibility event: multipart/related;boundary=example-3;start=pvmap;
type=application/alto-endpointcost+json,ecspvsub1
data: --example-3
data: Content-ID: pvmap
data: Content-Type: application/alto-endpointcost+json
data:
data: <endpoint-cost-map-entry>
data: --example-3
data: Content-ID: nepmap
data: Content-Type: application/alto-propmap+json
data:
data: <property-map-entry>
data: --example-3--
9.1. Compatibility with Base ALTO Clients/Servers Then, the ALTO server will subscribe the whole tree of the multipart
message automatically.
The path vector extension on Filtered Cost Map and Endpoint Cost When the data updated, the ALTO server will publish the data updates
Service is backward compatible with the base ALTO protocol: for each node in this tree separately.
o If the ALTO server provides extended capabilities "dependent- event: application/merge-patch+json,ecspvsub1.pvmap
property-map" and "allow-compound-response" for Filtered Cost Map data: <Merge patch for endpoint-cost-map-update>
or Endpoint Cost Service, but the client only supports the base
ALTO protocol, then the client will ignore those capabilities
without conducting any incompatibility.
o If the client sends a request with the input parameter event: application/merge-patch+json,ecspvsub2.nepmap
"properties", but the server only supports the base ALTO protocol, data: <Merge patch for property-map-update>
the server will ignore this field.
9.2. Compatibility with Multi-Cost Extension 10. Compatibility
This document does not specify how to integrate the "array" cost mode 10.1. Compatibility with Base ALTO Clients/Servers
and the "ane-path" cost metric with the multi-cost extension
[RFC8189]. Although there is no reason why somebody has to compound
the path vectors with other cost types in a single query, there is no
compatible issue doing it without constraint tests.
As Section 7.1.2 mentions, the syntax and semantics of whether The Multipart Filtered Cost Map resource and the Multipart Endpoint
"constraints" or "or-constraints" field for the "array" cost mode is Cost resource has no backward compatibility issue with the base ALTO
not specified in this document. So if an ALTO server provides a clients and servers. Although these two types of resources reuse the
resource with the "array" cost mode and the capability "cost- media types defined in the base ALTO protocol for the accept input
constraints" or "testable-cost-types-names", the ALTO client MAY parameters, they have different media types for responses. If the
ignore the capability "cost-constraints" or "testable-cost-types- ALTO server provides these two types of resources, but the ALTO
names" unless the implementation or future documents specify the client does not support them, the ALTO client will ignore the
behavior. resources without conducting any incompatibility.
9.3. Compatibility with Incremental Update 10.2. Compatibility with Multi-Cost Extension
This document does not specify how to integrate the "path-vector"
cost mode with the multi-cost extension [RFC8189]. Although there is
no reason why somebody has to compound the path vectors with other
cost types in a single query, there is no compatible issue doing it
without constraint tests.
10.3. Compatibility with Incremental Update
As this document still follows the basic request/response protocol As this document still follows the basic request/response protocol
with JSON encoding, it is surely compatible with the incremental with JSON encoding, it is surely compatible with the incremental
update service as defined by [I-D.ietf-alto-incr-update-sse]. But update service as defined by [I-D.ietf-alto-incr-update-sse]. But
the following details are to be noticed: the following details are to be noticed:
o When using the compound response, updates on both cost map and o When using the compound response, updates on both cost map and
property map SHOULD be notified. property map SHOULD be notified.
o When not using the compound response, because the cost map is in o When not using the compound response, because the cost map is in
the "uses" attribute of the property map, once the path vectors in the "uses" attribute of the property map, once the path vectors in
the cost map change, the ALTO server MUST send the updates of the the cost map change, the ALTO server MUST send the updates of the
cost map before the updates of the property map. cost map before the updates of the property map.
10. General Discussions 11. General Discussions
10.1. Provide Calendar for Property Map 11.1. Provide Calendar for Property Map
Fetching the historical network information is useful for many Fetching the historical network information is useful for many
traffic optimization problem. [I-D.ietf-alto-cost-calendar] already traffic optimization problem. [I-D.ietf-alto-cost-calendar] already
proposes an ALTO extension called Cost Calendar which provides the proposes an ALTO extension called Cost Calendar which provides the
historical cost values using Filtered Cost Map and Endpoint Cost historical cost values using Filtered Cost Map and Endpoint Cost
Service. However, the calendar for only path costs is not enough. Service. However, the calendar for only path costs is not enough.
For example, as the properties of ANEs (e.g., available bandwidth and For example, as the properties of ANEs (e.g., available bandwidth and
link delay) are usually the real-time network states, they change link delay) are usually the real-time network states, they change
frequently in the real network. It is very helpful to get the frequently in the real network. It is very helpful to get the
historical value of these properties. Applications may predicate the historical value of these properties. Applications may predicate the
network status using these information to better optimize their network status using these information to better optimize their
performance. performance.
So the coming requirement may be a general calendar service for the So the coming requirement may be a general calendar service for the
ALTO information resources. ALTO information resources.
10.2. Constraint Tests for General Cost Types 11.2. Constraint Tests for General Cost Types
The constraint test is a simple approach to query the data. It The constraint test is a simple approach to query the data. It
allows users to filter the query result by specifying some boolean allows users to filter the query result by specifying some boolean
tests. This approach is already used in the ALTO protocol. tests. This approach is already used in the ALTO protocol.
[RFC7285] and [RFC8189] allow ALTO clients to specify the [RFC7285] and [RFC8189] allow ALTO clients to specify the
"constraints" and "or-constraints" tests to better filter the result. "constraints" and "or-constraints" tests to better filter the result.
However, the current defined syntax is too simple and can only be However, the current defined syntax is too simple and can only be
used to test the scalar cost value. For more complex cost types, used to test the scalar cost value. For more complex cost types,
like the "array" mode defined in this document, it does not work like the "array" mode defined in this document, it does not work
well. It will be helpful to propose more general constraint tests to well. It will be helpful to propose more general constraint tests to
better perform the query. better perform the query.
In practice, it is too complex to customize a language for the In practice, it is too complex to customize a language for the
general-purpose boolean tests, and can be a duplicated work. So it 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 may be a good idea to integrate some already defined and widely used
query languages (or their subset) to solve this problem. The query languages (or their subset) to solve this problem. The
candidates can be XQuery and JSONiq. candidates can be XQuery and JSONiq.
10.3. General Compound Resources Query 11.3. General Multipart Resources Query
As the last paragraph of Section 4.3 mentions, querying multiple ALTO Querying multiple ALTO information resources continuously MAY be a
information resources continuously is a general requirement. And the general requirement. And the coming issues like inefficiency and
coming issues like inefficiency and inconsistency are also general. inconsistency are also general. There is no standard solving these
There is no standard solving these issues yet. So we need some issues yet. So we need some approach to make the ALTO client request
approach to make the ALTO client request the compound ALTO the compound ALTO information resources in a single query.
information resources in a single query.
11. Security Considerations 12. Security Considerations
This document is an extension of the base ALTO protocol, so the This document is an extension of the base ALTO protocol, so the
Security Considerations of the base ALTO protocol fully apply when Security Considerations [RFC7285] of the base ALTO protocol fully
this extension is provided by an ALTO server. apply when this extension is provided by an ALTO server.
The path vector extension requires additional considerations on two The path vector extension requires additional considerations on two
security considerations discussed in the base protocol: security considerations discussed in the base protocol:
confidentiality of ALTO information (Section 15.3 of [RFC7285]) and confidentiality of ALTO information (Section 15.3 of [RFC7285]) and
availability of ALTO service (Section 15.5 of [RFC7285]). availability of ALTO service (Section 15.5 of [RFC7285]).
For confidentiality of ALTO information, a network operator should be For confidentiality of ALTO information, a network operator should be
aware of that this extension may introduce a new risk: the path aware of that this extension may introduce a new risk: the path
vector information may make network attacks easier. For example, as vector information may make network attacks easier. For example, as
the path vector information may reveal more network internal the path vector information may reveal more network internal
skipping to change at page 25, line 42 skipping to change at page 23, line 33
Even if there is no intentional attack, the dependent property map of Even if there is no intentional attack, the dependent property map of
path vector might be still dynamically enriched, in that every new path vector might be still dynamically enriched, in that every new
request for path vectors will make the ALTO server generate a new request for path vectors will make the ALTO server generate a new
property map. So the properties of the abstract network elements can property map. So the properties of the abstract network elements can
consume a large amount of resources when cached. To avoid this, the consume a large amount of resources when cached. To avoid this, the
ALTO server providing the path vector extension should support a ALTO server providing the path vector extension should support a
time-to-live configuration for the property map, so that the outdated time-to-live configuration for the property map, so that the outdated
entries can be removed from the property map resource. entries can be removed from the property map resource.
12. IANA Considerations 13. IANA Considerations
12.1. ALTO Cost Mode Registry
This document specifies a new cost mode "array". However, the base
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
registry is defined either in a revised version of [RFC7285] or in
another future extension.
12.2. ALTO Cost Metric Registry
A new cost metric needs to be registered in the "ALTO Cost Metric
Registry", listed in Table 2.
+-------------+---------------------+ 13.1. ALTO Cost Mode Registry
| Identifier | Intended Semantics |
+-------------+---------------------+
| ane-path | See Section 5.2 |
+-------------+---------------------+
Table 2: ALTO Cost Metrics This document specifies a new cost mode "path-vector". However, the
base 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 registry is defined either in a revised version of [RFC7285] or
in another future extension.
12.3. ALTO Entity Domain Registry 13.2. ALTO Entity 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 Domain Entity Registry" is requested. Besides, a new domain is "ALTO Domain Entity Registry" is requested. Besides, a new domain is
to be registered, listed in Table 3. to be registered, listed in Table 1.
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
| Identifier | Entity Address Encoding | Hierarchy & Inheritance | | Identifier | Entity Address Encoding | Hierarchy & Inheritance |
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
| ane | See Section 6.2 | None | | ane | See Section 6.2 | None |
+-------------+--------------------------+--------------------------+ +-------------+--------------------------+--------------------------+
Table 3: ALTO Entity Domain Table 1: ALTO Entity Domain
12.4. ALTO Network Element Property Type Registry 13.3. ALTO Property Type Registry
The "ALTO Abstract Network Element Property Type Registry" is The "ALTO Property Type Registry" is required by the ALTO Domain
required by the ALTO Domain "ane", listed in Table 4. "ane", listed in Table 2.
+-------------+--------------------------+ +-------------+------------+----------------------------------------+
| Identifier | Intended Semantics | | Identifier | Intended | Dependencies and Interpretation |
+-------------+--------------------------+ | | Semantics | |
| availbw | The available bandwidth | +-------------+------------+----------------------------------------+
| delay | The transmission delay | | ane:maxresb | The | application/alto-costmap+json, or |
+-------------+--------------------------+ | w | maximum | application/alto-endpointcostmap+json, |
| | reservable | where the ANE names are used. |
| | bandwidth | |
| | for the | |
| | ANE | |
+-------------+------------+----------------------------------------+
Table 4: ALTO Abstract Network Element Property Types Table 2: ALTO Abstract Network Element Property Types
13. Acknowledgments 14. Acknowledgments
The authors would like to thank discussions with Andreas Voellmy, The authors would like to thank discussions with Andreas Voellmy,
Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan
Liu, Xiao Shi, Xin Wang, and Yan Luo. The authors thank Greg Liu, Xiao Shi, Xin Wang, and Yan Luo. The authors thank Greg
Bernstein (Grotto Networks), Dawn Chen (Tongji University), Wendy Bernstein (Grotto Networks), Dawn Chen (Tongji University), Wendy
Roome, and Michael Scharf for their contributions to earlier drafts. Roome, and Michael Scharf for their contributions to earlier drafts.
14. References 15. References
14.1. Normative References 15.1. 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, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, <https://www.rfc-editor.org/info/ DOI 10.17487/RFC2119, March 1997,
rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
14.2. Informative References 15.2. Informative References
[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.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-incr-update-sse]
Roome, W., Yang, Y., and S. Chen, "ALTO Incremental Roome, W. and Y. Yang, "ALTO Incremental Updates Using
Updates Using Server-Sent Events (SSE)", draft-ietf-alto- Server-Sent Events (SSE)", draft-ietf-alto-incr-update-
incr-update-sse-15 (work in progress), December 2018. sse-16 (work in progress), March 2019.
[I-D.ietf-alto-performance-metrics]
Wu, Q., Yang, Y., Lee, Y., Dhody, D., and S. Randriamasy,
"ALTO Performance Cost Metrics", draft-ietf-alto-
performance-metrics-06 (work in progress), November 2018.
[I-D.ietf-alto-unified-props-new] [I-D.ietf-alto-unified-props-new]
Roome, W., Chen, S., xinwang2014@hotmail.com, x., Yang, Roome, W., Randriamasy, S., Yang, Y., and J. Zhang,
Y., and J. Zhang, "Extensible Property Maps for the ALTO "Unified Properties for the ALTO Protocol", draft-ietf-
Protocol", draft-ietf-alto-unified-props-new-01 (work in alto-unified-props-new-07 (work in progress), March 2019.
progress), December 2017.
[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
Kai Gao Kai Gao
Tsinghua University Tsinghua University
Beijing Beijing Beijing Beijing
China China
Email: gaok12@mails.tsinghua.edu.cn Email: gaok12@mails.tsinghua.edu.cn
Young Lee Young Lee
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