ALTO WG G. Bernstein
Internet-Draft Grotto Networking
Intended status: Standards Track S. Chen
Expires: November 4, 2017 Tongji University
K. Gao
Tsinghua University
Y. Lee
Huawei
W. Roome
M. Scharf
Nokia
Y. Yang
Yale University
J. Zhang
Tongji University
May 3, 2017
ALTO Extension: Path Vector Cost Mode
draft-ietf-alto-path-vector-00.txt
Abstract
The Application-Layer Traffic Optimization (ALTO) Service has defined
network and cost maps to provide basic network information, where the
cost maps allow only scalar (numerical or ordinal) cost mode values.
This document introduces a new cost mode called path-vector to allow
ALTO clients to support use cases such as capacity regions for
applications. This document starts with a non-normative example
called multi-flow scheduling (or capacity region) to illustrate that
ALTO cost maps without path vectors cannot provide sufficient
information. This document then defines path-vector as a new cost
mode.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 4, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Use Case: Capacity Region for Multi-Flow Scheduling . . . . . 5
4. Overview of Approach . . . . . . . . . . . . . . . . . . . . 7
4.1. Path Vector Data Format . . . . . . . . . . . . . . . . . 7
4.2. Network Element Property Map . . . . . . . . . . . . . . 8
4.3. Flow Query Format . . . . . . . . . . . . . . . . . . . . 8
4.4. Query Specific . . . . . . . . . . . . . . . . . . . . . 8
5. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 8
5.1. Cost Type . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1.1. Cost Metric . . . . . . . . . . . . . . . . . . . . . 9
5.1.2. Cost Mode: Path Vector . . . . . . . . . . . . . . . 9
5.2. Version Tag . . . . . . . . . . . . . . . . . . . . . . . 9
5.3. Network Element Name . . . . . . . . . . . . . . . . . . 10
5.4. ANE Domain . . . . . . . . . . . . . . . . . . . . . . . 10
5.4.1. Domain Name . . . . . . . . . . . . . . . . . . . . . 10
5.4.2. Domain-Specific Entity Addresses . . . . . . . . . . 10
5.5. Filtered Network Element Property Map . . . . . . . . . . 10
5.5.1. Accept Input Parameters . . . . . . . . . . . . . . . 10
5.5.2. Capabilities . . . . . . . . . . . . . . . . . . . . 11
5.5.3. Response . . . . . . . . . . . . . . . . . . . . . . 11
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5.6. IRD Extensions . . . . . . . . . . . . . . . . . . . . . 11
5.7. Cost Map Extensions . . . . . . . . . . . . . . . . . . . 12
5.7.1. Propertymap . . . . . . . . . . . . . . . . . . . . . 12
5.7.2. Response . . . . . . . . . . . . . . . . . . . . . . 12
5.8. Filtered Cost Map Extensions . . . . . . . . . . . . . . 12
5.8.1. Capabilities . . . . . . . . . . . . . . . . . . . . 12
5.8.2. Accept Input Parameters . . . . . . . . . . . . . . . 13
5.8.3. Propertymap . . . . . . . . . . . . . . . . . . . . . 14
5.8.4. Response . . . . . . . . . . . . . . . . . . . . . . 14
5.9. Endpoint Cost Service Extensions . . . . . . . . . . . . 14
5.9.1. Capabilities . . . . . . . . . . . . . . . . . . . . 15
5.9.2. Accept Input Parameters . . . . . . . . . . . . . . . 15
5.9.3. Propertymap . . . . . . . . . . . . . . . . . . . . . 16
5.9.4. Response . . . . . . . . . . . . . . . . . . . . . . 16
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Workflow . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Information Resource Directory Example . . . . . . . . . 17
6.3. Cost Map Example . . . . . . . . . . . . . . . . . . . . 19
6.4. Multi-Cost Filtered Cost Map Example . . . . . . . . . . 20
6.5. Endpoint Cost Service Example . . . . . . . . . . . . . . 22
6.6. Network Element Property Map Example # 1 . . . . . . . . 23
6.7. Network Element Property Map Example # 2 . . . . . . . . 24
7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 25
7.1. Compatibility with Legacy ALTO Clients/Servers . . . . . 25
7.2. Compatibility with Multi-Cost Extensions . . . . . . . . 25
7.3. Compatibility with Incremental Update . . . . . . . . . . 26
8. Time to live . . . . . . . . . . . . . . . . . . . . . . . . 26
9. Design Decisions and Discussions . . . . . . . . . . . . . . 26
9.1. Path Vector or Path Graph . . . . . . . . . . . . . . . . 26
9.2. Provide More General Calendar Extension . . . . . . . . . 27
9.3. Snapshot and real-time update . . . . . . . . . . . . . . 27
10. Security Considerations . . . . . . . . . . . . . . . . . . . 27
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
11.1. ALTO Cost Mode Registry . . . . . . . . . . . . . . . . 28
11.2. ALTO Cost Metric Registry . . . . . . . . . . . . . . . 28
11.3. ALTO Entity Domain Registry . . . . . . . . . . . . . . 28
11.4. ALTO Network Element Property Type Registry . . . . . . 29
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
13.1. Normative References . . . . . . . . . . . . . . . . . . 29
13.2. Informative References . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction
The ALTO base protocol [RFC7285] is designed for exposing network
information through services such as the Network Map service and the
Cost Map service. These services use the extreme "single-node"
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abstraction, which represents the whole network with a single node
and hosts are connected to the node's access ports.
Although the "single-node" abstraction works well for many settings,
new use cases, such as inter-datacenter data transfers and scientific
high-performance computing data transfers, require additional network
information beyond the single-node abstraction, to support
application capabilities, in particular, the ability of application
flow scheduling.
Specifically, providing network information to support application
flow scheduling introduces multiple complexities. First, the
underlying assumption of existing ALTO services is single-commodity
flows. Hence, given the flow from a source to a destination, ALTO
computes the network metrics of the flow and returns them to the
application. The metric values for different flows are independent.
Application flow scheduling, however, requires network information to
compute application-desirable multi-commodity flows, where multiple
flows under the control of the same application may share common
network bottlenecks. This requirement is beyond the capability of
the single-node abstraction adopted by the base ALTO protocol.
Second, some flow scheduling problems may consider end-to-end metrics
at the same time and thus require multiple costs to be updated
simultaneously. Such a requirement, even though already addressed by
[I-D.ietf-alto-multi-cost], still needs to be handled very carefully.
To address these complexities in supporting the new flow scheduling
use case, this document specifies a path-vector extension to the base
ALTO protocol. This extension introduces a new cost type, which uses
"path-vector" as cost mode and "ane" (abstract network element) as
cost metric. It extends "Filtered Property Map" defined in
[I-D.roome-alto-unified-props] to address the issue of scalability
and consistency in providing path vectors with fine-grained
information. This document also registers a new entity domain,
entity specification and properties in the ALTO Entity Domain
Registry. Besides, (Filtered) Cost Map and Endpoint Cost Service are
extended to support path-vector and flow query format. The concept
of "query specific" is put forward to correlate the response
information of (Filtered) Cost Map/Endpoint Cost service and query of
property map.
The document is organized as follows. Section 3 gives an example of
flow scheduling to illustrate the need to introduce cost mode "path-
vector" and cost metric "ane". Section 4 gives an overview of the
path-vector extension. Section 5 specifies the new cost mode and
cost metric, new domain type, entity properties and protocol
extensions for (Filtered) Cost Maps and Endpoint Cost Services.
Section 6 presents several examples. Section 7 discusses the
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compatibility issues with some other proposed ALTO extensions.
Section 8 discusses the time to live problem. Section 9 discusses
several design decisions. Section 10 and Section 11 discusses about
security and IANA Considerations.
2. Terminology
This document uses the following terms: Network Element, Network
Element Name, Network Element Property, Network Element Property Map
and Path Vector.
o Network Element (NE): A Network Element is an abstract network
element, which can be a link, a network switching device, or a set
of devices.
o Network Element Name (NEN): The id of a NE. It can be referenced
by Cost Map, Filtered Cost Map, Endpoint Cost Service and Property
Map.
o Network Element Property (NEP): The property of a NE. It can be
the available bandwidth of a link, the delay or other available
properties.
o Network Element Property Map (NEP Map): It is a Filtered Property
Map resource defined in [I-D.roome-alto-unified-props] and
supports "ane" domain in its "domain-types" capability.
o Cost Map, Filtered Cost Map, Endpoint Cost Service: If not
explained explicitly, they are the same definition as of
[I-D.ietf-alto-multi-cost] by default.
o Path Vector (PV): An array of NENs. It can be used to convey the
routing information.
3. Use Case: Capacity Region for Multi-Flow Scheduling
Consider the case that routing is given. Then what application-layer
traffic optimization will focus on is traffic scheduling among
application-layer paths. Specifically, assume that an application
has control over a set of flows F = {f_1, f_2, ..., f_|F|}. If
routing is given, what the application can control is x_1, x_2, ...,
x_|F|, where x_i is the amount of traffic for flow i. Let x = [x_1,
..., x_|F|] be the vector of the flow traffic amounts. Due to shared
links, feasible values of x where link capacities are not exceeded
can be a complex polytype.
Specifically, consider a network as shown in Figure 1. The network
has 7 switches (sw1 to sw7) forming a dumb-bell topology. Switches
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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
connected to access switches sw1 to sw4 respectively. Assume that
the bandwidth of each link is 100 Mbps.
+------+
| |
--+ sw6 +--
/ | | \
PID1 +-----+ / +------+ \ +-----+ PID2
eh1__| |_ / \ ____| |__eh2
| sw1 | \ +--|---+ +---|--+ / | sw2 |
+-----+ \ | | | |/ +-----+
\_| sw5 +---------+ sw7 |
PID3 +-----+ / | | | |\ +-----+ PID4
eh3__| |__/ +------+ +------+ \____| |__eh4
| sw3 | | sw4 |
+-----+ +-----+
Figure 1: Raw Network Topology.
The single-node ALTO topology abstraction of the network is shown in
Figure 2.
+----------------------+
{eh1} | | {eh2}
PID1 | | PID2
+------+ +------+
| |
| |
{eh3} | | {eh4}
PID3 | | PID4
+------+ +------+
| |
+----------------------+
Figure 2: Base Single-Node Topology Abstraction.
Consider an application overlay (e.g., a large data analysis system)
which needs to schedule the traffic among a set of end host source-
destination pairs, say eh1 -> eh2, and eh3 -> eh4. The application
can request a cost map providing end-to-end available bandwidth,
using 'availbw' as cost-metric and 'numerical' as cost-mode.
Assume that the application receives from the ALTO server that the
bandwidth of eh1 -> eh2 and eh3 ->eh4 are both 100 Mbps. It cannot
determine that if it schedules the two flows together, whether it
will obtain a total of 100 Mbps or 200 Mbps. This depends on whether
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the routing paths of the two flows share a bottleneck in the
underlying topology:
o Case 1: If eh1 -> eh2 and eh3 -> eh4 use different paths, for
example, when the first uses sw1 -> sw5 -> sw7 -> sw2, and the
second uses sw3 -> sw5 -> sw6 -> sw7 -> sw4. Then the application
will obtain 200 Mbps.
o Case 2: If eh1 -> eh2 and eh3 -> eh4 share a bottleneck, for
example, when both use the direct link sw5 -> sw7, then the
application will obtain only 100 Mbps.
To allow applications to distinguish the two aforementioned cases,
the network needs to provide more details. In particular, it needs
to provide the following new capabilities:
o The network needs to expose more detailed routing information to
show the shared bottlenecks.
o The network needs to provide the necessary abstraction to hide the
real topology information as possible.
The path-vector extension defined in this document will satisfy all
the requirements.
See [I-D.bernstein-alto-topo] for a survey of use-cases where
extended network topology information is needed.
4. Overview of Approach
This section presents a non-normative overview of the path-vector
extension defined in this document. It assumes the readers are
familiar with (Filtered) Cost Map and Endpoint Cost Service defined
in [RFC7285], their extensions defined in [I-D.ietf-alto-multi-cost]
and Filtered Property Map defined in [I-D.roome-alto-unified-props].
4.1. Path Vector Data Format
The path-vector extension defined in this document introduces "path-
vector" as a cost mode, where a path vector between two entities
(either PIDs or endpoints) is an array of abstract network elements.
Each abstract network element is represented by a name. An abstract
network element can be a link, a network switching device, or a set
of devices.
One issue of introducing path vectors is how to encode them. The
cost entries contained in an ALTO (Filtered) Cost Map or Endpoint
Cost Service are formally defined in Section 11.2.3.6 of [RFC7285] to
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be any type of JSON value. But the section also suggests that
implementations may assume the cost values are numbers unless
specifically defined by an extension. This document extends the
definition of Cost Map and Endpoint Cost Map to allow the returned
cost to be a path vector, which is a JSONArray of Network Element
Names.
4.2. Network Element Property Map
The response with only the names of network elements does not provide
enough information. To be useful to applications, the extension need
to provide desired properties of the abstract network elements as
well. This document registers a new entity domain "ane" and entity
specifications. The Filtered Property Map defined in
[I-D.roome-alto-unified-props] supporting "ane" domain (named Network
Element Property Map) is used for ALTO clients to retrieve the
properties of abstract network elements.
4.3. Flow Query Format
Current queries of the (Filtered) Cost Map/Endpoint Cost Service are
of cross-product format. Such format fails to support lists of
single src to single dst costs. So the input scheme of the Filtered
Cost Map and Endpoint Cost Service is extended to support the above
flow query format.
4.4. Query Specific
Path Vector extension has raised a new occasion that different
resources can be associated with the same query. Here, the cost path
vector of the (Filtered) Cost Map/Endpoint Cost Service and the
properties of the abstract network elements of the Network Element
Property Map are generated at the same time and they are related.
So, a query-specific attribute "query-id" is introduced in the "vtag"
to express such information. Also, the input parameters of the
Network Element Property Map is extended to support the query-
specific queries.
5. Protocol Extensions
This section formally specifies the path-vector extension which
includes the following components: a new cost type, a new entity
domain, extensions of (Filtered) Cost Map and Endpoint Cost Map.
Below we specify each component in details.
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5.1. Cost Type
The path-vector extension defined in this document enriches the cost
types defined in Section 6.1 of [RFC7285].
5.1.1. Cost Metric
This document specifies a new cost metric: "ane". It is of type
CostMetric as defined in Section 10.6 of [RFC7285]. The cost metric
"ane" MUST NOT be used when the cost mode is not "path-vector" unless
it is explicitly specified in a future extension. Meanwhile, an ALTO
server with path-vector extension MUST support the cost metric "ane".
Cost metric "ane": This cost metric MUST be encoded as the
JSONString "ane". When cost metric is "ane", Network Element
Names contained in the path vectors MUST be query-specific.
5.1.2. Cost Mode: Path Vector
This document specifies a new cost mode: "path-vector". The path-
vector cost mode is of type CostMode as defined in Section 6.1.2 of
[RFC7285] and is encoded as the JSONString "path-vector".
A (Filtered) Cost Map resource or Endpoint Cost Service, when queried
with this cost mode, MUST return a CostMapData or EndpointCostMapData
whose cost value is a JSONArray of type NetworkElementName as
specified in Section 5.3.
This cost mode MUST be used with the cost metric "ane" unless it is
explicitly specified by a future extension.
5.2. Version Tag
To support the concept of query specific, a new field named "query-
id" is introduced to correlate the query information between the
(Filtered) Cost Map/Endpoint Cost Service response and the
corresponding property map query. The object VersionTag as defined
in Section 10.3 of [RFC7285] is extended as follows:
object {
ResourceID resource-id;
JSONString tag;
[JSONString query-id;]
} VersionTag;
resource-id, tag: As defined in Section 10.3 of [RFC7285].
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query-id: A string used to uniquely identify the abstract network
elements in the property map.
5.3. Network Element Name
This document also extends [RFC7285] with a new basic data type:
NetworkElementName. A NetworkElementName is of type EntityAddr as
defined in Section 2.3 of [I-D.roome-alto-unified-props] and is
encoded as a JSONString. A NetworkElementName MUST be an EntityAddr
of the ANE domain (Section 5.4).
5.4. ANE Domain
This document specifies a new domain in addition to the ones in
[I-D.roome-alto-unified-props].
5.4.1. Domain Name
ane
5.4.2. Domain-Specific Entity Addresses
The entity address of ane domain is encoded as a JSON string. The
string MUST be no more than 64 characters, and it MUST NOT contain
characters other than US-ASCII alphanumeric characters
(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+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.
5.5. Filtered Network Element Property Map
A Filtered Network Element Property Map MUST be a Filtered Property
Map as defined in Section 5 of [I-D.roome-alto-unified-props].
5.5.1. Accept Input Parameters
This document extends ReqFilteredPropertyMap defined in Section 5.3
of [I-D.roome-alto-unified-props] by introducing an optional field
named "query-id". The ReqFilteredPropertyMap is extended as follows:
object {
EntityAddr entities<1..*>
PropertyName properties<1..*>;
[JSONString query-id;]
} ReqFilteredPropertyMap;
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entities, properties: The same as defined in Section 5.3 of
[I-D.roome-alto-unified-props].
query-id: Like the "query-id" defined in Section 5.2, the "query-id"
here is also a string used to uniquely identify the abstract
network elements in the property map.
5.5.2. Capabilities
A Network Element Property Map MUST have capabilities "domain-types"
and "prop-types" as defined in Section 4.4 of
[I-D.roome-alto-unified-props]. The "domain-types" capability MUST
contain domain "ane". And the "prop-types" capability MUST be a
subset of property types which are registered with the "ALTO Network
Element Property Type Registry" defined in Section 11.4 of this
document.
5.5.3. Response
The response is the same as for the Property Map, as defined in
Section 4.6 of [I-D.roome-alto-unified-props], except that only the
requested entities and properties are returned for Filtered Network
Element Map. Examples can be found in Section 6.6 and Section 6.7.
5.6. IRD Extensions
This document extends IRDResourceEntry defined in Section 9.2.2 of
[RFC7285] by introducing a new entry named "propertymap". The
IRDResourceEntry object is extended as follows:
object {
JSONString uri;
JSONString media-type;
[JSONString accepts;]
[Capabilities capabilities;]
[ResourceID uses<0..*>;]
[ResourceID propertymap<0..*>;]
} IRDResourceEntry;
uri, media-type, accepts, capabilities, uses: The same as defined in
Section 9.2.2 of [RFC7285].
propertymap: A list of resource IDs, defined in the same IRD, that
indicates where the specific properties of the returned abstract
network elements can be retrieved.
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5.7. Cost Map Extensions
This document extends Cost Map defined in Section 11.2.3 of [RFC7285]
by returning JSONArray instead of JSONNumber as the cost value,
including "vtag" in "meta" field in the response, and adding a new
field referencing to the Network Element Property Map.
The media type, HTTP method, capabilities, accept input parameter and
uses specifications are unchanged.
5.7.1. Propertymap
If the Cost Map supports the path-vector extension, the field
"propertymap" provides a list of resource ids of Network Element
Property Map. Each network element property map resource provides
properties for the dynamically generated abstract network elements.
5.7.2. Response
The response is the same as defined in Section 11.2.3.6 of [RFC7285]
except the follows:
o If the cost mode is "path-vector", the cost is a JSONArray of
Network Element Names.
o If the query sent by the client includes cost type path vector,
the "vtag" filed defined in Section 5.2 has to be included in the
response. And the "query-id" information in "vtag" MUST be
provided to clients.
5.8. Filtered Cost Map Extensions
This document extends the Filtered Cost Map defined in Section 4.1 of
[I-D.ietf-alto-multi-cost] by specifying details on capabilities,
returning JSONArray instead of JSONNumber as the cost value,
including "vtag" in "meta" field in the response, and adding a new
field referencing to the Network Element Property Map.
The media type, HTTP method and uses specifications are unchanged.
5.8.1. Capabilities
The FilteredCostMapCapabilities object is the same as defined in
Section 4.1.1 of [I-D.ietf-alto-multi-cost] expect the follow:
testable-cost-type-names: Cost type "path-vector" MUST NOT appear in
the "testable-cost-type-names" field.
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5.8.2. Accept Input Parameters
The ReqFilteredCostMap defined in Section 4.1.2 of
[I-D.ietf-alto-multi-cost] is extended, the meanings and the
constraints of some fields are also extended.
object {
[CostType cost-type;]
[CostType multi-cost-types<1..*>;]
[CostType testable-cost-types<1..*>;]
[JSONString constraints<0..*>;]
[JSONString or-constraints<1..*><1..*>;]
[PIDFilter pids;]
[PIDFlowFilter pid-flows<1..*>;]
} ReqFilteredCostMap;
object {
PIDName src;
PIDName dst;
} PIDFlowFilter;
cost-type: If the cost type is path-vector and neither the
"testable-cost-type-names" field is provided by the server nor the
"testable-cost-types" field is provided by the client, the
"constraints" field and the "or-constraints" field SHOULD NOT
appear. If not, the ALTO server MUST return an error with error
code E_INVALID_FIELD_VALUE. The server MAY include an optional
field named "field" in the "meta" field of the response, the value
of "field" is "constraints" or "or-constraints". The server MAY
also include an optional field named "value" in the "meta" field,
the value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
multi-cost-types: If "multi-cost-types" includes cost type path-
vector, meanwhile, neither the "testable-cost-type-names" field is
provided by the server nor the "testable-cost-types" field is
provided by the client, the cost type index of path-vector MUST
NOT appear in the "constraints" field or the "or-constraints"
field. If not, the ALTO server MUST return an error with error
code E_INVALID_FIELD_VALUE. The server MAY include an optional
field named "field" in the "meta" field of the response, the value
of "field" is "constraints" or "or-constraints". The server MAY
also include an optional field named "value" in the "meta" field,
the value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
testable-cost-types: "testable-cost-types" SHOULD NOT include path-
vector cost type. If "testable-cost-types" contains path-vector
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cost type, the ALTO server MUST return an error with error code
E_INVALID_FIELD_VALUE. The server MAY include an optional field
named "field" in the "meta" field of the response, the value of
"filed" is "testable-cost-types/cost-mode". The server MAY also
include an optional field named "value" in the "meta" field, the
value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
pid-flows: A list of PID src to PID dst for which path costs are to
be returned.
Additional requirement is that the Client MUST specify either "pids"
or "pid-flows", but MUST NOT specify both.
5.8.3. Propertymap
If the Filtered Cost Map supports the path-vector extension, the
field "propertymap" provides a list of resource ids of Network
Element Property Map. Each network element property map resource
provides properties for the dynamically generated abstract network
elements.
5.8.4. Response
The response is the same as defined in Section 4.1.3 of
[I-D.ietf-alto-multi-cost] except the follows:
o Whether the "cost-type" field or the "multi-cost-types" field
includes cost type path-vector, the cost is a JSONArray of Network
Element Names.
o If the query sent by the client includes cost type path vector,
the "vtag" filed defined in Section 5.2 has to be included in the
response. And the "query-id" information in "vtag" MUST be
provided to clients.
5.9. Endpoint Cost Service Extensions
This document extends the Endpoint Cost Service defined in
Section 4.2 in [I-D.ietf-alto-multi-cost] by specifying details on
capabilities, returning JSONArray instead of JSONNumber as the cost
value, including "vtag" in "meta" field in the response, and adding a
new field referencing to the Network Element Property Map.
The media type, HTTP method and uses specifications are unchanged.
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5.9.1. Capabilities
The same as defined in Section 5.8.1.
5.9.2. Accept Input Parameters
The ReqFilteredCostMap defined in Section 4.1.2 of
[I-D.ietf-alto-multi-cost] is extended, the meanings and the
constraints of some fields are also extended.
``` object { [CostType cost-type;][CostType multi-cost-types<1..*>;]
[CostType testable-cost-types<1..*>;][JSONString constraints<0..*>;]
[JSONString or-constraints<1.._><1.._>;][EndpointFilter endpoints;]
[EndpointFlowFilter endpoint-flows<1..*>;] } ReqEndpointCostMap;
object { TypedEndpointAddr src; TypedEndpointAddr dst; }
EndpointFlowFilter; ```
cost-type: If the cost type is path-vector and neither the
"testable-cost-type-names" field is provided by the server nor the
"testable-cost-types" field is provided by the client, the
"constraints" field and the "or-constraints" field SHOULD NOT
appear. If not, the ALTO server MUST return an error with error
code E_INVALID_FIELD_VALUE. The server MAY include an optional
field named "field" in the "meta" field of the response, the value
of "field" is "constraints" or "or-constraints". The server MAY
also include an optional field named "value" in the "meta" field,
the value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
multi-cost-types: If "multi-cost-types" includes cost type path-
vector, meanwhile, neither the "testable-cost-type-names" field is
provided by the server nor the "testable-cost-types" field is
provided by the client, the cost type index of path-vector MUST
NOT appear in the "constraints" field or the "or-constraints"
field. If not, the ALTO server MUST return an error with error
code E_INVALID_FIELD_VALUE. The server MAY include an optional
field named "field" in the "meta" field of the response, the value
of "field" is "constraints" or "or-constraints". The server MAY
also include an optional field named "value" in the "meta" field,
the value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
testable-cost-types: "testable-cost-types" SHOULD NOT include path-
vector cost type. If "testable-cost-types" contains path-vector
cost type, the ALTO server MUST return an error with error code
E_INVALID_FIELD_VALUE. The server MAY include an optional field
named "field" in the "meta" field of the response, the value of
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"filed" is "testable-cost-types/cost-mode". The server MAY also
include an optional field named "value" in the "meta" field, the
value of "value" is "path-vector". If the "value" field is
specified, the "field" field MUST be specified.
endpoint-flows: A list of endpoint src to endpoint dst for which
path costs are to be returned.
Additional requirement is that the Client MUST specify either
"endpoints" or "endpoint-flows", but MUST NOT specify both.
5.9.3. Propertymap
If the Endpoint Cost Service supports the path-vector extension, the
field "propertymap" provides a list of resource ids of Network
Element Property Map. Each network element property map resource
provides properties for the dynamically generated abstract network
elements.
5.9.4. Response
The response is the same as defined in Section 4.2.3 of
[I-D.ietf-alto-multi-cost] except the follows:
o Whether the "cost-type" field or the "multi-cost-types" field
includes cost type path-vector, the cost is a JSONArray of Network
Element Names.
o If the query sent by the client includes cost type path vector,
the "vtag" filed defined in Section 5.2 has to be included in the
response. And the "query-id" information in "vtag" MUST be
provided to clients.
6. Examples
This section lists a series of examples to proceed the multi-flow
scheduling like the use case in Section 3.
The recommended workflow is like the following:
6.1. Workflow
o Send the GET request for the whole Information Resource Directory.
o Look for the resource of the (Filtered) Cost Map/Endpoint Cost
Service which contains the path-vector cost type and get the
resource id of the property map.
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o Look for the resource of the property map to check whether it
supports the desired "prop-types".
o Send request to the (Filtered) Cost Map/Endpoint Cost Service and
get the response with "query-id" information. Meanwhile, the
properties of the returned abstract network elements are generated
in the corresponding Network Element Property Map.
o Send request to the Network Element Property Map with the returned
"query-id" information and get the response.
6.2. Information Resource Directory Example
Here is an example of an ALTO server's Information Resource
Directory. In this example, both "filtered-multi-cost-map" and
"default-endpoint-cost-map" support the multi-cost extension and the
path-vector extension. Resource "ane-property-map-availbw" supports
property "availbw" and resource "ane-property-map-delay" supports
property "delay".
"meta": {
"cost-types": {
"pv-ane": {
"cost-mode": "path-vector",
"cost-metric": "ane"
},
"num-hopcount": {
"cost-mode": "numerical",
"cost-metric": "hopcount"
},
"num-routingcost": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
},
}
},
"resources": {
... NetworkMap Resource ...
"default-network-map": {
"uri": "http://alto.example.com/networkmap",
"media-type": "application/alto-networkmap+json"
},
... Cost Map Resource ...
"pv-cost-map": {
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"uri": "http://alto.example.com/pv/ane",
"media-type": "application/alto-costmap+json",
"capabilities": {
"cost-type-names": ["pv-ane"]
},
"uses": ["default-network-map"],
"propertymap": ["ane-property-map-delay",
"ane-property-map-availbw"]
}
... Multi-Cost Filtered Map Resource ...
"filtered-multi-cost-map": {
"uri": "http://alto.example.com/costmap/multi/filtered",
"media-type": "application/alto-costmap+json",
"accepts": "application/alto-costmapfilter+json",
"uses": ["default-network-map"],
"capabilities": {
"max-cost-types": 3,
"cost-type-names": ["pv-ane",
"num-routingcost",
"num-hopcount"],
"cost-constraints": true
},
"propertymap": ["ane-property-map-delay",
"ane-property-map-availbw"]
},
... Endpoint Cost Service Resource ...
"default-endpoint-cost-map": {
"uri": "http://alto.example.com/endpointcost/lookup",
"media-type": "application/alto-endpointcostmap+json",
"accepts": "application/alto-endpointcostparams+json",
"capabilities": {
"max-cost-types": 3,
"cost-type-names": ["pv-ane",
"num-routingcost",
"num-hopcount"],
"testable-cost-types-names": ["num-hopcount",
"num-routingcost"],
},
"propertymap": ["ane-property-map-delay"]
}
... Network Element Property Map Resource ...
"ane-property-map-delay": {
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"uri": "http://alto.example.com/propmap/lookup/delay",
"media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json",
"capabilities": {
"domain-types": ["ane"],
"prop-types": ["delay"]
}
}
"ane-property-map-availbw": {
"uri": "http://alto.example.com/propmap/lookup/availbw",
"media-type": "application/alto-propmap+json",
"accepts": "application/alto-propmapparams+json",
"capabilities": {
"domain-types": ["ane"],
"prop-types": ["availbw"]
}
}
}
6.3. Cost Map Example
Here is an example of the Cost Map request for path-vector and the
corresponding response. In response, the extended "vtag" field is
included in "meta" to provide "query-id" information.
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GET /costmap/pv/ane HTTP/1.1
Host: alto.example.com
Accept: application/alto-costmap+json,application/alto-error+json
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-costmap+json
{
"meta" : {
"dependent-vtags" : [
{ "resource-id": "default-network-map",
"tag": "5eb2cb7f8d63a9fab71d9b34cbf763436315542f"
}
],
"vtag": [
{ "resource-id": "pv-cost-map",
"tag": "aef527ca2eb7a7566db0597407893e3f8eb1d9dff",
"query-id": "query0"
}
],
"cost-type" : {"cost-mode" : "pv",
"cost-metric": "ane"
}
},
"cost-map" : {
"PID1": { "PID2": ["ane:L001", "ane:L003"],
"PID3": ["ane:L002", "ane:L004"] },
"PID2": { "PID1": ["ane:L003", "ane:L002"],
"PID3": ["ane:L003", "ane:L004"] },
"PID3": { "PID1": ["ane:L004", "ane:L002"],
"PID2": ["ane:L004", "ane:L003"] }
}
}
6.4. Multi-Cost Filtered Cost Map Example
The following example presents the request and response of "filtered-
multi-cost-map". In this example, the client is interested in the
path-vector and numerical routing cost information. The client uses
"or-constraints" but all the results satisfy the conditions. In
resposne, the extended "vtag" field is included in "meta" to provide
"query-id" information.
POST /costmap/multi/filtered HTTP/1.1
Host: alto.example.com
Accept: application/alto-costmap+json,application/alto-error+json
Content-Length: [TBD]
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Content-Type: application/alto-costmapfilter+json
{
"multi-cost-types": [
{
"cost-mode": "path-vector",
"cost-metric": "ane"
},
{
"cost-mode": "numerical",
"cost-metric": "routingcost"
}
],
"testable-cost-types": [
{ "cost-mode": "numerical", "cost-metric": "routingcost" },
{ "cost-mode": "numerical", "cost-metric": "hopcount" }
],
"or-constraints": [
["[0] ge 50", "[1] le 60"]
],
"pid-flows": [
{ "src": "PID1", "dst": "PID2" },
{ "src": "PID2", "dst": "PID3" }
]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-costmap+json
{
"meta": {
"dependent-vtags": [
{
"resource-id": "default-network-map",
"tag": "75ed013b3cb58f896e839582504f622838ce670f"
}
],
"vtag": [
{
"resource-id": "filtered-multi-cost-map",
"tag": "27612897acf278ffu3287c284dd28841da78213",
"query-id": "query1"
}
]
}
"cost-type": {},
"multi-cost-types": [
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{ "cost-mode": "path-vector", "cost-metric": "ane" },
{ "cost-mode": "numerical", "cost-metric": "routingcost"}
],
"cost-map": {
"PID1": {
"PID2": [ [ "ane:L001", "ane:L003" ], 55 ]
},
"PID2": {
"PID3": [ [ "ane:L003", "ane:L004" ], 60 ]
}
}
}
6.5. Endpoint Cost Service Example
If the ALTO client expects the routing state information between
endpoints, it can also query the "default-endpoint-cost-map" resource
which supports path vector. In resposne, the extended "vtag" field
is included in "meta" to provide "query-id" information.
POST /endpointcost/lookup HTTP/1.1
Host: alto.example.com
Accept: application/alto-endpointcost+json,application/alto-error+json
Content-Length: [TBD]
Content-Type: application/alto-endpointcostparams+json
{
"multi-cost-types": [
{ "cost-mode": "path-vector", "cost-metric": "ane" },
{ "cost-mode": "numerical", "cost-metric": "hopcount" }
],
"endpoint-flows": [
{ "src": "ipv4:192.0.2.2", "dst": "ipv4:203.0.113.45" },
{ "src": "ipv4:192.0.2.89", "dst": "ipv4:198.51.100.34" },
{ "src": "ipv4:194.2.3.67", "dst": "ipv4:202.56.54.230" },
{ "src": "ipv4:203.32.56.102", "dst": "ipv4:202.76.89.103" }
]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-endpointcost+json
{
"meta": {
"vtag": [
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{
"resource-id": "default-endpoint-cost-map",
"tag": "73182ffa829dc28c218a1823bb1293dea232885",
"query-id": "query2"
}
],
"cost-type": {},
"multi-cost-types": [
{ "cost-mode": "path-vector", "cost-metric": "ane" },
{ "cost-mode": "numerical", "cost-metric": "hopcount" }
]
},
"endpoint-cost-map": {
"ipv4:192.0.2.2": {
"ipv4:203.0.113.45": [ [ "ane:L10", "ane:L11",
"ane:L15", "ane:L16",
"ane:L17", "ane:L13" ], 100]
},
"ipv4:192.0.2.89": {
"ipv4:198.51.100.34": [ [ "ane:L14", "ane:L11",
"ane:L12", "ane:L18",
"ane:L19" ], 124]
},
"ipv4:194.2.3.67": {
"ipv4:202.56.54.230": [ [ "ane:L21", "ane:L15",
"ane:L16", "ane:L17",
"ane:L18", "ane:L20"], 78]
},
"ipv4:203.32.56.102": {
"ipv4:202.76.89.103": [ [ "ane:L22", "ane:L16",
"ane:L23"], 168]
}
}
}
6.6. Network Element Property Map Example # 1
After the client send the query to the Multi-Cost Filtered Cost Map
"filtered-multi-cost-map" and get the response with query-id "query1"
(See Section 6.4). The client send request to the "ane-property-map-
availbw" with query-id "query1" and get the response.
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POST /propmap/lookup/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": "query1",
"entities" : [ "ane:L001",
"ane:L003",
"ane:L004" ],
"properties" : [ "availbw" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-propmap+json
{
"property-map": {
"ane:L001": { "availbw": "50" },
"ane:L003": { "availbw": "70" },
"ane:L004": { "availbw": "80" }
}
}
6.7. Network Element Property Map Example # 2
After the client send the query to the Endpoint Cost Service
"default-endpoint-cost-map" and get the response with query-id
"query2" (See Section 6.5). The client send request to the "ane-
property-map-delay" with query-id "query2" and get the response.
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POST /propmap/lookup/delay 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": "query2",
"entities" : [ "ane:L11",
"ane:L15",
"ane:L16",
"ane:L18" ],
"properties" : [ "delay" ]
}
HTTP/1.1 200 OK
Content-Length: [TBD]
Content-Type: application/alto-propmap+json
{
"property-map": {
"ane:L11": { "delay": "25" },
"ane:L15": { "delay": "40" },
"ane:L16": { "delay": "60" },
"ane:L18": { "delay": "10" }
}
}
7. Compatibility
7.1. Compatibility with Legacy ALTO Clients/Servers
Legacy ALTO clients SHOULD NOT send queries with path vector
extension and ALTO servers with this extension SHOULD NOT have any
compatibility issue. Legacy ALTO servers do not support cost types
with the "path-vector" cost mode and MUST NOT announce the extended
cost types in IRD. Thus, ALTO clients MUST NOT send queries
specified in this extension to legacy ALTO servers according to
Section 11.3.2.3 [RFC7285].
7.2. Compatibility with Multi-Cost Extensions
Path Vector is not a testable cost type. So two conditions have to
be satisfied when multi-cost supports path-vector extension. Any
format of constraints SHOULD NOT be applied to cost type path-vector.
o Cost type path-vector MUST NOT be included in "testable-cost-
types-names" or "testable-cost-types".
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o When "testable-cost-types-names" is omitted in the "capabilities"
and "testable-cost-types" is omitted in the input parameters,
"constraints" or "or-constraints" SHOULD NOT add any format of
constraints on cost type path-vector.
7.3. Compatibility with Incremental Update
There is no compatibility issue with incremental update extension.
8. Time to live
The Network Element Property Map is dynamically enriched when the
(Filtered) Cost Map/Endpoint Cost Service is queried of the path-
vector information. The properties of the abstract network elements
can consume a large amount of resources when cached. So, a time-to-
live is needed to remove outdated entries in the Network Element
Property Map.
9. Design Decisions and Discussions
9.1. Path Vector or Path Graph
When we introduce the "path-vector" as a cost mode in the Cost Map,
an unavoidable problem is how to handle multipath. Because a PID is
a group of endpoints, it is common that there are multiple paths
between two PIDs. The valid routing state information is all of the
accessible paths. So in this scenario, the Cost Map Resource SHOULD
provide the cost values including of the multiple paths.
A natural solution is to provide an array of path vectors as the cost
value. Every path vector in this array means an accessible path
between the source PID and the destination PID. It is different from
the solution of the path vector extension which provides an array of
network elements. So it requires to introduce a different cost mode.
This document proposes this new cost mode named "path-graph".
However, the "path-graph" will increase the complexity of the Cost
Map Response. Since the applications select ALTO as the protocol to
get the network information rather than other topology-based solution
such as I2RS, the major reason should be the simplicity. If we
provide "path-graph" for each PID pairs, the ALTO client has to
handle the complex data structure.
What's more, the "path-vector" is powerful enough to express multiple
paths. The simple solution is to list the network elements of all
accessible paths in a single path vector. This solution will lose
the information about paths. Another solution is to define the path
as a new type of network elements. In this way, the path vector can
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provide an array of paths. Each element of this array contains a
path vector of network elements in the Network Element Property Map.
So in this document, we just introduce "path-vector" as the only
required cost mode for routing state information.
9.2. Provide More General Calendar Extension
Cost Calendar is proposed as a useful ALTO extension to provide the
historical cost values for Filtered Cost Map Service and Endpoint
Cost Service. Since path vector is an extension to these services,
it SHOULD be compatible with Cost Calendar extension.
However, the calendar of a path-vector (Endpoint) Cost Map is
insufficient for the application which requires the historical data
of routing state information. The (Endpoint) Cost Map can only
provide the changes of the paths. But more useful information is the
history of network element properties which are recorded in the
dependent Network Element Property Map.
Before the Unified Property Map is introduced as an ALTO extension,
Filtered Cost Map Service and Endpoint Cost Service are the only
resources which require the calendar supported. Because other
resources don't have to be updated frequently. But Network Element
Property Map as a use case of Unified Property Map will collect the
real-time information of the network. It SHOULD be updated as soon
as possible once the metrics of network elements change.
So the requirement is to provide a general calendar extension which
not only meets the Filtered Cost Map and Endpoint Cost Service but
also applies to the Property Map Service.
9.3. Snapshot and real-time update
As the suggested workflow mentioned in Section 6.1, the properties of
the abstract network elements are computed ahead of the query of
these properties. So the properties of abstract network elements are
likely to be snapshot rather than realt-time value when queried.
10. Security Considerations
We can identify multiple potential security issues. A main security
issue is network privacy, as the path-vector information may reveal
more network internal structures than the more abstract single-node
abstraction. The network should consider protection mechanisms to
reduce information exposure, in particular, in settings where the
network and the application do not belong to the same trust domain.
On the other hand, in a setting of the same trust domain, a key
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benefit of the path-vector abstraction is reduced information
transfer from the network to the application.
The path-vector query may also reveal more information about the
application. In particular, the application may reveal all potential
transfers sites (e.g., where the data source is replicated, and where
the potential replication sites are). The application should
evaluate the potential privacy concerns.
Beyond the privacy issues, the computation of the path-vector is
unlikely to be cachable, in that the results will depend on the
particular requests (e.g., where the flows are distributed). Hence,
this service may become an entry point for denial of service attacks
on the availability of an ALTO server. Hence, authenticity and
authorization of this ALTO service may need to be better protected.
11. IANA Considerations
11.1. ALTO Cost Mode Registry
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.
11.2. ALTO Cost Metric Registry
A new cost metric needs to be registered in the "ALTO Cost Metric
Registry", listed in Table 1.
+-------------+---------------------+
| Identifier | Intended Semantics |
+-------------+---------------------+
| ane | See Section 5.1.1 |
+-------------+---------------------+
Table 1: ALTO Cost Metrics
11.3. ALTO Entity Domain 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 2.
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+-------------+--------------------------+--------------------------+
| Identifier | Entity Address Encoding | Hierarchy & Inheritance |
+-------------+--------------------------+--------------------------+
| ane | See Section 5.4.2 | None |
+-------------+--------------------------+--------------------------+
Table 2: ALTO Entity Domain
11.4. ALTO Network Element Property Type Registry
The "ALTO Network Element Property Type Registry" is required by the
ALTO Entity Domain "ane", listed in Table 3.
+-------------+--------------------------+
| Identifier | Intended Semantics |
+-------------+--------------------------+
| availbw | The available bandwidth |
| delay | The transmission delay |
+-------------+--------------------------+
Table 3: ALTO Network Element Property Types
12. Acknowledgments
The authors would like to thank discussions with Andreas Voellmy,
Erran Li, Haibin Son, Haizhou Du, Jiayuan Hu, Qiao Xiang, Tianyuan
Liu, Xiao Shi, Xin Wang, and Yan Luo.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
13.2. Informative References
[I-D.amante-i2rs-topology-use-cases]
Medved, J., Previdi, S., Lopez, V., and S. Amante,
"Topology API Use Cases", draft-amante-i2rs-topology-use-
cases-01 (work in progress), October 2013.
[I-D.bernstein-alto-topo]
Bernstein, G., Yang, Y., and Y. Lee, "ALTO Topology
Service: Uses Cases, Requirements, and Framework", draft-
bernstein-alto-topo-00 (work in progress), October 2013.
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[I-D.clemm-i2rs-yang-network-topo]
Clemm, A., Medved, J., Tkacik, T., Varga, R., Bahadur, N.,
and H. Ananthakrishnan, "A YANG Data Model for Network
Topologies", draft-clemm-i2rs-yang-network-topo-01 (work
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]
Randriamasy, S., Yang, Y., Wu, Q., Lingli, D., and N.
Schwan, "ALTO Cost Calendar", draft-ietf-alto-cost-
calendar-01 (work in progress), February 2017.
[I-D.ietf-alto-incr-update-sse]
Roome, W. and Y. Yang, "ALTO Incremental Updates Using
Server-Sent Events (SSE)", draft-ietf-alto-incr-update-
sse-03 (work in progress), September 2016.
[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]
Lee, Y., Bernstein, G., Choi, T., and D. Dhody, "ALTO
Extensions to Support Application and Network Resource
Information Exchange for High Bandwidth Applications",
draft-lee-alto-app-net-info-exchange-02 (work in
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.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<http://www.rfc-editor.org/info/rfc7285>.
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Authors' Addresses
Greg Bernstein
Grotto Networking
Fremont, CA
USA
Email: gregb@grotto-networking.com
Shiwei Dawn Chen
Tongji University
4800 Caoan Road
Shanghai 201804
China
Email: dawn_chen_f@hotmail.com
Kai Gao
Tsinghua University
Beijing Beijing
China
Email: gaok12@mails.tsinghua.edu.cn
Young Lee
Huawei
TX
USA
Email: leeyoung@huawei.com
Wendy Roome
Nokia/Bell Labs
600 Mountain Ave, Rm 3B-324
Murray Hill, NJ 07974
USA
Phone: +1-908-582-7974
Email: wendy.roome@nokia.com
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Michael Scharf
Nokia
Germany
Email: michael.scharf@nokia.com
Y. Richard Yang
Yale University
51 Prospect St
New Haven CT
USA
Email: yry@cs.yale.edu
Jingxuan Jensen Zhang
Tongji University
4800 Caoan Road
Shanghai 201804
China
Email: jingxuan.n.zhang@gmail.com
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