Internet DRAFT - draft-randriamasy-alto-cost-calendar
draft-randriamasy-alto-cost-calendar
Network Working Group S. Randriamasy
Internet-Draft Alcatel-Lucent Bell Labs
Intended status: Standards Track R. Yang
Expires: April 21, 2016 Yale University
Q. Wu
Huawei
L. Deng
China Mobile
N. Schwan
Thales Deutschland
October 19, 2015
ALTO Cost Calendar
draft-randriamasy-alto-cost-calendar-05
Abstract
The goal of Application-Layer Traffic Optimization (ALTO) is to
bridge the gap between network and applications by provisioning
network related information in order to allow applications to make
network informed decisions. The present draft extends the ALTO cost
information so as to broaden the decision possibilities of
applications to not only decide 'where' to connect to, but also
'when'. This is useful to applications that need to schedule their
data transfers and connections and have a degree of freedom to do so.
ALTO guidance to schedule application traffic can also efficiently
help for load balancing and resources efficiency. Besides, the ALTO
Cost Calendar allows to schedule the ALTO requests themselves and
thus to save a number of ALTO transactions.
This draft proposes new capabilities and attributes on filtered cost
maps and endpoint costs enabling an ALTO Server to provide "Cost
Calendars". These capabilities are applicable to time-sensitive ALTO
metrics. With ALTO Cost Calendars, an ALTO Server exposes ALTO Cost
Values in JSON arrays where each value corresponds to a given time
interval. The time intervals as well as other Calendar attributes
are specified in the IRD and ALTO Server responses.
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].
Randriamasy, et al. Expires April 21, 2016 [Page 1]
Internet-Draft ALTO Cost Calendar October 2015
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at 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 April 21, 2016.
Copyright Notice
Copyright (c) 2015 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
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview of ALTO Cost Calendars . . . . . . . . . . . . . . . 5
2.1. ALTO Cost Calendar information features . . . . . . . . . 5
2.2. ALTO Calendar design characteristics . . . . . . . . . . 6
2.2.1. ALTO Cost Calendar for all cost modes . . . . . . . . 7
2.2.2. Compatibility with legacy ALTO Clients . . . . . . . 7
3. ALTO Calendar specification: IRD extensions . . . . . . . . . 7
3.1. Calendar attributes in the IRD resources capabilities . . 8
3.2. Calendars in a delegate IRD . . . . . . . . . . . . . . . 9
3.3. Example IRD with ALTO Cost Calendars . . . . . . . . . . 9
4. ALTO Calendar specification: Service Information Resources . 12
4.1. Calendar extensions for Filtered Cost Maps . . . . . . . 13
4.1.1. Calendar extensions in Filtered cost map requests . . 13
4.1.2. Calendar extensions in Filtered Cost map responses . 14
Randriamasy, et al. Expires April 21, 2016 [Page 2]
Internet-Draft ALTO Cost Calendar October 2015
4.1.3. Example transaction for a FCM with a bandwidth
Calendar . . . . . . . . . . . . . . . . . . . . . . 15
4.2. Calendar extensions in the Endpoint Cost Map Service . . 17
4.2.1. Calendar specific input in Endpoint cost map
requests . . . . . . . . . . . . . . . . . . . . . . 17
4.2.2. Calendar attributes in the Endpoint Cost Map response 17
4.2.3. Example transaction for the ECS with a routingcost
Calendar . . . . . . . . . . . . . . . . . . . . . . 18
4.2.4. Example transaction for the ECS with a calendar for
both routingcost and latency . . . . . . . . . . . . 20
4.3. Recap of rules related to ALTO Cost Calendars . . . . . . 22
5. Use cases for ALTO Cost Schedule . . . . . . . . . . . . . . 22
5.1. Bulk Data Transfer scheduling upon bandwidth calendars . 22
5.1.1. Applicable example transaction . . . . . . . . . . . 23
5.2. Applications with limited connectivity or access to
datacenters . . . . . . . . . . . . . . . . . . . . . . . 24
5.2.1. Applicable example transaction . . . . . . . . . . . 25
5.3. SDN Controller guided traffic scheduling with Calendars . 25
5.3.1. Applicable example transaction . . . . . . . . . . . 26
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
6.1. Information for IANA on proposed Cost Types . . . . . . . 26
6.2. Information for IANA on proposed Endpoint Propeeries . . 26
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.1. Normative References . . . . . . . . . . . . . . . . . . 26
8.2. Informative References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
IETF is currently standardizing the ALTO protocol which aims at
providing guidance to overlay applications needing to select one or
several hosts from a set of candidates able to provide a desired
resource. This guidance is based on parameters that affect
performance and efficiency of the data transmission between the hosts
such as the topological distance. The goal of ALTO is to improve the
Quality of Experience (QoE) in the application while optimizing
resource usage in the underlying network infrastructure.
The ALTO protocol in [RFC7285] specifies a Network Map which defines
groupings of endpoints in provider-defined network regions (called
PIDs). The Cost Map Service, Endpoint Cost Service (ECS) and
Endpoint Ranking Service then provide ISP-defined costs and rankings
for connections among the specified endpoints and PIDs and thus
incentives for application clients to connect to ISP preferred
locations, e.g. to reduce their costs. ALTO intentionally avoids
provisioning realtime information as explained in the ALTO Problem
Statement [RFC5693] and ALTO Requirements [RFC5693].Thus the current
Randriamasy, et al. Expires April 21, 2016 [Page 3]
Internet-Draft ALTO Cost Calendar October 2015
Cost Map and Endpoint Cost Service are providing, for a given Cost
Type, exactly one path cost value. Applications have to query one of
these two services to retrieve the currently valid cost values. They
therefore need to plan their ALTO information requests according to
their own estimation of the frequency of cost value change.
With [RFC7285], an ALTO client should interpret the returned costs as
those at the query moment. However, Network costs can fluctuate,
e.g. due to diurnal patterns of traffic demand or planned events such
as network maintenance, holidays or highly publicized events.
Providing network costs for only the current time thus may not be
sufficient, in particular for applications that can schedule their
traffic in a span of time, for example by deferring backup to night
during traffic trough.
In case the ALTO Cost value changes are predicable over a certain
period of time and the application does not require immediate data
transfer, it can save time to get the whole set of cost values over
this period in one ALTO response. Using them to schedule data
transfers would allow to optimise the network resources usage and
QoE. ALTO Clients and Servers can also minimize their workload by an
appropriate scheduling of their data exchanges.
This document extends RFC7285 to allow an ALTO server to provide
network costs for a given duration of time. A sequence of network
costs across a time span for a given pair of network locations is
named an "ALTO Cost Calendar". The Filtered Cost Map Service and
Endpoint Cost Service are extended to provide Cost Calendars. In
addition to this functional ALTO enhancement, we expect to further
gain on storage and on the wire data exchange by gathering multiple
Cost Values for one Cost Type into one single ALTO Server response.
In this draft an "ALTO Cost Calendar" is specified by information
resources capabilities that are applicable to time-sensitive ALTO
metrics. An ALTO Cost Calendar exposes ALTO Cost Values in JSON
arrays where each value corresponds to a given time interval. The
time intervals as well as other Calendar attributes are specified in
the IRD and in the Server response to allow the ALTO Client to
interpret the received ALTO values. Last, the proposed extensions
for ALTO Calendars are applicable to any Cost Mode and they ensure
backwards compatibility with legacy ALTO clients.
In the rest of this document, Section 2 provides the design
characteristics. Sections 3 and 4 define the formal specification
for the IRD and the information resources. Section 5 provides non-
normative use cases to illustrate the usage of cost calendars. IANA
considerations and security considerations will be completed in
further versions.
Randriamasy, et al. Expires April 21, 2016 [Page 4]
Internet-Draft ALTO Cost Calendar October 2015
2. Overview of ALTO Cost Calendars
An ALTO Cost calendar provided by the ALTO Server provides 2
information items:
o an array of values for a given metric, where each value
corresponds to a time interval, wher the value array can sometimes
be a cyclic pattern that repeats a certain number of times.
o attributes describing the time scope of the calendar, allowing an
ALTO Client to properly interpret the values, such as the size and
number of the intervals and the date of the starting point of the
calendar.
An ALTO Cost Calendar can be used like a "time table" to figure out
the best time to schedule data transfers and also to proactively
manage appllication traffic given predictable events such as flash
crowds, traffic intensive holidays and network maintenance. An ALTO
Cost Calendar may be viewed as a synthetic abstraction of real
measurements that can be historic or be a prediction for upcoming
time periods.
Most likely, the ALTO Cost Calendar would be used for the Endpoint
Cost Service, assuming that a limited set of feasible Endpoints for a
non-real time application is already identified, that they do not
need to be accessed immediately and that their access can be
scheduled within a given time period. The Filtered Cost Map service
is also applicable as long as the size of the Map allows it.
2.1. ALTO Cost Calendar information features
The Calendar attributes are provided in the IRD and in ALTO Server
responses. The IRD announces attributes with dateless values in its
information resources capabilities, where as attributes with time
dependent values are provided in the "meta" of Server responses. The
ALTO Cost Calendar attributes provide the following information:
o attributes to interpret the time scope of the Calendar value
array:
* generic time zone,
* applicable time interval for each calendar value: combining
numbers and time units to reflect for example: 1 hour, 2
minutes, 10 seconds, 1 week, 1 month,
* duration of the Calendar: e.g. the number of intervals provided
in the calendar.
Randriamasy, et al. Expires April 21, 2016 [Page 5]
Internet-Draft ALTO Cost Calendar October 2015
o "calendar-start-date": specifying when the calendar starts, that
is to which date the first value of the cost calendar is
applicable.
o "repeated": an optional attribute indicating how many iterations
the provided calendar will have the same values, that the server
may use to allow the client to schedule its next request and thus
save its own workload by avoiding to process useless requests.
2.2. ALTO Calendar design characteristics
This draft introduces new capabilities and attributes that specify an
ALTO Cost Calendar. The protocol extension placeholders are: the
IRD, the ALTO requests and responses for Cost calendars.
Extensions are designed to be light and ensure backwards
compatibility with base protocol ALTO Clients and with other
extensions. It uses section 8.3.7 "Parsing of Unknown Fields" of
RFC7285 that writes: "Extensions may include additional fields within
JSON objects defined in this document. ALTO implementations MUST
ignore unknown fields when processing ALTO messages."
The calendar specific capabilities are integrated in the information
resources of the IRD and in the "meta" member of ALTO responses to
Cost Calendars requests. A calendar and its capabilities are
associated to a given information resource and within this
information resource to a given cost type. This design has several
advantages:
o it does not introduce a new mode,
o it does not introduce new media types,
o it allows an ALTO Server to offer calendar capabilities on a cost
type, with attributes values adapted to each information resource.
The Applicable Calendared information resources are:
o the Filtered Cost Map,
o the Endpoint Cost Map.
The ALTO Server can choose in which frequency it provides cost
Calendars to ALTO Clients. It may either provide calendar updates
starting at the request date, or carefully schedule its updates so as
to take profit from a potential repetition/periodicity of calendar
values.
Randriamasy, et al. Expires April 21, 2016 [Page 6]
Internet-Draft ALTO Cost Calendar October 2015
2.2.1. ALTO Cost Calendar for all cost modes
Calendars are well-suited for values encoded in the 'numerical' mode.
However, Calendars can also represent any metric considered as time-
sensitive by an ALTO Server. For example, types of Cost values such
as JSONBool can also be expressed as calendars, as states may be
"true" or "false" depending on given time periods or likewise, values
represented by strings, such as "medium", "high", "low", "blue",
"open" .
Note also that a Calendar is applicable as well to time-sensitive
metrics provided in the 'ordinal' mode, if these values are time-
sentitive and their update is carefully managed by the ALTO Server.
2.2.2. Compatibility with legacy ALTO Clients
The ALTO protocol extensions for Cost Calendars have been defined so
as to ensure that Calendar capable ALTO Servers can provide legacy
ALTO Clients with legacy information resources as well. That is a
legacy ALTO Client can request resources and receive responses as
specified in RFC7285.
For compatibility with legacy ALTO Clients specified in RFC7285,
calendared information resources are not applicable for Cost Maps for
the following reason: a legacy ALTO client would receive a Calendared
Cost Map via an HTTP 'GET' command. As specified in section 8.3.7 of
RFC7285, it will ignore the Calendar Attributes indicated in the
"meta" of the responses. Therefore, lacking information on calendar
attributes, it will not be able to correctly interpret and process
the values of the received array of calendar cost values.
3. ALTO Calendar specification: IRD extensions
The Calendar attributes in the IRD information resources capabilities
carry constant dateless values. A calendars is associated to an
information resource rather than a cost type. For example, a Server
can provide a "routingcost" values calendar for the Filtered Cost Map
Service at a granularity of one day and a "routingcost" values
calendar for the Endpoint Cost service at a finer granularity but for
a limited number of endpoints.
NOTE : to cope with existing representation fomats and proposed
unified ALTO naming schemes proposed in the WG, the names given in
the current proposal may be revised in further versions.
Randriamasy, et al. Expires April 21, 2016 [Page 7]
Internet-Draft ALTO Cost Calendar October 2015
3.1. Calendar attributes in the IRD resources capabilities
When for an applicable resource , an ALTO Server provides a Cost
Calendar for a given Cost Type, it MUST indicate this in the IRD
capabilities of this resource, by an object of type
'CalendarAttributes', associated to this Cost Type and specified
below.
The capabilities of a Calendar aware information resource entry have
a member named "calendar-attributes" which is an array of objects of
type CalendarAttributes. The array has as many values as cost-type-
names announced for the resource. It is necessary to use an array
because of resources such as Filtered Cost Map and Endpoint Cost Map,
for which the member "cost-type-names" is an array of 1 or more
values. If for a given cost-type-name of this ressource no Calendar
attributes are defined, the ALTO Server MUST replace that value in
the array by the symbol 'null'.
RULE: a member "calendar-attributes" MUST appear only once for each
applicable cost type name of a resource entry. If "calendar-
attributes" are specified several times for a same "cost-type-name"
in the capabilities of a resource entry, the ALTO client SHOULD
ignore any calendar capabilities on this "cost-type-name" for this
entry.
CalendarAttributes calendar-attributes <1..*>;
object{
[JSONString cost-type-name;]
JSONString time-interval-size;
JSONNumber number-of-intervals;
} CalendarAttributes;
o "cost-type-name":
* an optional member indicating the cost-type-name in the IRD
entry to which the capabilities apply. If this not present, it
MUST be assumed to correspond to its index in the "cost-type-
names" list of the IRD resource entry.
o "time-interval-size":
* is the duration of an ALTO calendar time interval, expressed as
a time unit appended to the number of these units. The time
unit, ranges from "second" to "year". The number is encoded
with an integer. Example values are: "5 minute" , "2 hour",
meaning that each calendar value applies on a time interval
that lasts respectively 5 minutes and 2 hours.
Randriamasy, et al. Expires April 21, 2016 [Page 8]
Internet-Draft ALTO Cost Calendar October 2015
o "number-of-intervals":
* the integer number of values of the cost calendar array, at
least equal to 1.
- Attribute "cost-type-name" , if used, provides a better readability
to the calendar attributes specified in the IRD and avoids confusion
with calendar attributes of other cost-types.
- Multiplying Attributes 'time-interval-size' and 'number-of-
intervals' provides the duration of the provided calendar. For
example an ALTO Server may provide a calendar for ALTO values
changing every 'time-interval-size' equal to 5 minutes. If 'number-
of-intervals' has the value 12, then the duration of the provided
calendar is "1 hour".
3.2. Calendars in a delegate IRD
One option to clarify IRD resources is that a "root" ALTO Server
implementing base protocol resources delegates "specialized"
information resources such as the ones providing Cost Calendars to
another ALTO Server running in a subdomain specified with its URI in
the "root" ALTO Server. This option is described in Section 9.2.4
"Delegation using IRDs" of RFC7285.
This document provides an example, where a "root" ALTO Server runs in
a domain called "alto.example.com". It delegates the announcement of
Calendars capabilities to an ALTO Server running in a subdomain
called "custom.alto.example.com". The location of the "delegate
Calendar IRD" is assumed to be indicated in the "root" IRD by the
resource entry: "custom-calendared-resources".
Another advantage is that some Cost Types for some resources may be
more advantageous as Cost Calendars and it makes few sense to get
them as a single value. For example, Cost Types with predictable and
frequently changing values, calendared in short time intervals such
as a minute.
3.3. Example IRD with ALTO Cost Calendars
The cost types in this example are either specified in the base ALTO
protocol or may be proposed in other drafts see
[draft-wu-alto-te-metrics]. In this example the available cost
metrics are indicated in the "meta" field by cost type names "num-
routingcost", "num-latency", "num-pathbandwidth" and "string-quality-
status". Metrics "routingcost" , 'latency' and 'Availbandwidth' are
available in the "numerical" Cost Mode. Metric "quality-status" is
available in the "string" Cost Mode.
Randriamasy, et al. Expires April 21, 2016 [Page 9]
Internet-Draft ALTO Cost Calendar October 2015
This ALTO server does not provide a calendar for cost type name num-
AShopcount.
The example IRD includes 2 particular URIs providing calendars:
o "http://custom.alto.example.com/calendar/costmap/filtered": a
filtered cost map in which calendar capabilities are indicated for
cost type names: "num-routingcost", "num-pathbandwidth" and
"string-service-status",
o "http://custom.alto.example.com/endpointcost/calendar/lookup": an
endpoint cost map in which in which calendar capabilities are
indicated for cost type names: "num-routingcost", "num-TEpktloss",
"num-pathbandwidth", "string-service-status".
The design of the Calendar capabilities allows that some calendars on
a cost type name are available in several information resources with
different Calendar Attributes. This is the case for calendars on
"num-routingcost", "num-pathbandwidth" and "string-service-status" ,
available in both the Filtered Cost map and Endpoint Cost map
service, but with different time interval sizes for "num-
pathbandwidth" and "string-service-status".
GET /calendars-directory HTTP/1.1
Host: custom.alto.example.com
Accept: application/alto-directory+json,application/alto-error+json
---------------
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto-directory+json
{
"meta" : {
"cost-types": {
"num-routingcost": {
"cost-mode" : "numerical",
"cost-metric" : "routingcost"
},
"num-latency": {
"cost-mode" : "numerical",
"cost-metric": "latency"
},
"num-pathbandwidth": {
"cost-mode" : "numerical",
"cost-metric": "Availbandwidth",
},
"string-qual-status": {
Randriamasy, et al. Expires April 21, 2016 [Page 10]
Internet-Draft ALTO Cost Calendar October 2015
"cost-mode" : "string",
"cost-metric": "quality-status",
}
... other meta ...
},
"resources" : {
"filtered-cost-map-calendar" : {
"uri" : "http://custom.alto.example.com/calendar/costmap/filtered",
"media-type" : "application/alto-costmap+json",
"accepts" : "application/alto-costmapfilter+json",
"capabilities" : {
"cost-constraints" : true,
"cost-type-names" : [ "num-routingcost", "num-pathbandwidth",
"string-service-status" ],
"calendar-attributes" : [
{"cost-type-names" : [ "num-routingcost", "num-pathbandwidth" ],
"time-interval-size" : "1 hour",
"number-of-intervals" : 24
},
{"cost-type-names" : "string-service-status",
"time-interval-size" : "30 minute",
"number-of-intervals" : 48
}
] // end calendar-attributes
"uses": [ "my-default-network-map" ]
}
},
"endpoint-cost-calendar-map" : {
"uri" : "http://custom.alto.example.com/calendar/endpointcost/calendar/lookup",
"media-types" : [ "application/alto-endpointcost+json" ],
"accepts" : [ "application/alto-endpointcostparams+json" ],
"capabilities" : {
"cost-constraints" : true,
"cost-type-names" : [ "num-routingcost", "num-latency",
"num-pathbandwidth", "string-service-status" ],
"calendar-attributes" : [
{"cost-type-names" : "num-routingcost",
"time-interval-size" : "1 hour",
"number-of-intervals" : 24
},
{"cost-type-names" : "latency",
"time-interval-size" : "5 minute",
"number-of-intervals" : 12
},
{"cost-type-names" : "num-pathbandwidth",
"time-interval-size" : "1 minute",
Randriamasy, et al. Expires April 21, 2016 [Page 11]
Internet-Draft ALTO Cost Calendar October 2015
"number-of-intervals" : 60
},
{"cost-type-names" : "string-service-status",
"time-interval-size" : "2 minute",
"number-of-intervals" : 30
},
]
"uses": [ "my-default-network-map" ]
} // ECM capab
} //info resource N
} // ressources
In this example IRD, for the filtered cost map service, all calendars
have a duration of 1 day and start in the "request-date" mode, that
is the "date" of first value of the array belongs to the time
interval "containing" the date of the request.
o the Calendar for 'num-routingcost': is an array of 24 values each
provided on a time interval lasting 1 hour.
o the Calendar for 'num-pathbandwidth': is an array of 24 values
each provided on a time interval lasting 1 hour.
o the Calendar for "string-service-status": "is an array of 48
values each provided on a time interval lasting 30 minutes.
For the endpoint cost map service, the cost calendars have a duration
of 1 day for "num-routingcost" and 1 hour for the 3 other cost type
names.
o the Calendar for 'num-routingcost': is an array of 24 values each
provided on a time interval lasting 1 hour.
o the Calendar for 'latency'': is an array of 12 values each
provided on a time interval lasting 5 minutes.
o the Calendar for 'num-pathbandwidth': is an array of 60 values
each provided on a time interval lasting 1 minute.
o the Calendar for "string-service-status": "is an array of 30
values each provided on a time interval lasting 2 minutes.
4. ALTO Calendar specification: Service Information Resources
This section documents the individual information resources defined
to provide the Calendared information services defined in this
document.
Randriamasy, et al. Expires April 21, 2016 [Page 12]
Internet-Draft ALTO Cost Calendar October 2015
The reference time zone for the provided time values is GMT because
the option chosen to express the time format is the HTTP header
fields format:
Date: Tue, 15 Nov 1994 08:12:31 GMT
4.1. Calendar extensions for Filtered Cost Maps
A legacy ALTO client requests and gets filtered cost map responses as
specified in RFC7285.
4.1.1. Calendar extensions in Filtered cost map requests
The input parameters of a "legacy" request for a filtered cost map,
defined by object ReqFilteredCostMap in section 11.3.2 of RFC7285,
are augmented with one additional member.
A Calendar-aware ALTO client requesting a Calendar on a given Cost
Type for a Filtered Cost Map resource having Calendar capabilities
MUST add the following field to its input parameters:
JSONBoolean calendared<1..*>;
This field is an array of 1 to N boolean values, where N is the
number of requested metrics. Each boolean value indicates whether or
not the ALTO Server should provide the values for this Cost Type as a
calendar.
This field MUST NOT be specified if member "calendar-attributes" is
not present or has the value 'false' for this information resource.
A Calendar-aware ALTO client supporting single cost type values, as
specified in RFC7285, MUST provide an array of 1 element:
"calendared" : [true],
A Calendar-aware ALTO client that is also Multi-Cost aware MUST
provide an array of N values set to "true" or "false", depending
whether it wants the applicable Cost Type values as a single or
calendared value.
If this field is not present, it MUST be assumed to have only values
equal to "false".
Randriamasy, et al. Expires April 21, 2016 [Page 13]
Internet-Draft ALTO Cost Calendar October 2015
4.1.2. Calendar extensions in Filtered Cost map responses
The calendared costs are JSONArrays instead of JSONNumbers for the
legacy ALTO implementation. All arrays have a number of values equal
to 'number-of-intervals'.
The "meta" field of a Calendared Filtered Cost map response MUST
include at least:
o if the ALTO Client supports cost values for one Cost Type at a
time only: the "meta" fields specified specified in RFC 7285 for
these information service responses:
* "dependent-vtags ",
* "cost-type" field.
o if the ALTO Client supports cost values for several Cost Types at
a time, as specified in [draft-ietf-alto-multi-cost] : the "meta"
fields specified in [draft-ietf-alto-multi-cost] for these
information service responses:
* "dependent-vtags ",
* "multi-cost-types" field.
In addition, the "meta" field of a Calendared Filtered Cost map
response MUST include the member "calendar-response-attributes" for
the requested information resource, together with the values provided
by the ALTO Server for these attributes. This member is an array of
objects of type "CalendarResponseAttributes", defined as follows:
CalendarResponseAttributes calendar-response-attributes <1..*>;
object{
JSONString calendar-start-time;
JSONString time-interval-size;
JSONNumber number-of-intervals;
[JSONNumber repeated;] [OPTIONAL]
} CalendarResponseAttributes;
o "calendar-start-time": indicates the date at which the first value
of the calendar applies. By default, the value provided for the
"calendar-start-time" attribute SHOULD be no later than the
request date.
o "time-interval-size": as specified in section "Calendar attributes
in the IRD resources capabilities",
Randriamasy, et al. Expires April 21, 2016 [Page 14]
Internet-Draft ALTO Cost Calendar October 2015
o "number-of-intervals": as specified in section "Calendar
attributes in the IRD resources capabilities",
o "repeated": is an optional field provided for Calendars. It is an
integer N greater or equal to '1' that indicates how many
iterations of the calendar value array starting at the date
indicated by "calendar-start-time" have the same values. The
number N includes the provided iteration.
Using the member "repeated" helps minimizing on the wire data
exchange: by providing it, an ALTO Server will avoid unecessary
processing of requests for Calendars with unchanged values while it
allows ALTO Clients to save their resources as well.
For example: if the "calendar-start-time" member has value "Mon, 30
Jun 2014 at 00:00:00 GMT" and if the value of member "repeated" is
equal to 4, it means that the calendar values are the same values on
Monday, Tuesday, Wednesday and Thursday. The ALTO Client thus may
use the same calendar for the next 4 duration periods following
"calendar-start-time".
4.1.3. Example transaction for a FCM with a bandwidth Calendar
An example of non-real time information that can be provisioned in a
'calendar' is the expected path bandwidth. While the transmission
rate can be measured in real time by end systems, the operator of a
data center is in the position of formulating preferences for given
paths, at given time periods for example to avoid traffic peaks due
to diurnal usage patterns. In this example, we assume that an ALTO
Client requests a bandwidth calendar as specified in the IRD to
shedule its bulk data transfers as described in the use cases.
In the example IRD, calendars for cost type name "num-pathbandwidth"
are available for the information resources: "filtered-cost-calendar-
map" and "endpoint-cost-calendar-map". The ALTO Client requests a
calendar for "num-pathbandwidth" via a POST request for a filtered
cost map.
We suppose in this example that the ALTO Client sends its request on
Tuesday July 1st 2014 at 13:15
Randriamasy, et al. Expires April 21, 2016 [Page 15]
Internet-Draft ALTO Cost Calendar October 2015
POST /calendar/costmap/filtered HTTP/1.1
Host: alto.example.com
Content-Length: [TODO]
Content-Type: application/alto-costmapfilter+json
Accept: application/alto-costmap+json,application/alto-error+json
{
"cost-type" : {"cost-mode" : "numerical", "cost-metric" : "Availbandwidth"},
"calendared" : [true],
"pids" : {
"srcs" : [ "PID1", "PID2" ],
"dsts" : [ "PID1", "PID2", "PID3" ]
}
}
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto-costmap+json
{
"meta" : {
"dependent-vtags" : [...],
"cost-type" : {"cost-mode" : "numerical", "cost-metric" : "Availbandwidth"},
"calendar-response-attributes" : [
"calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT,
"time-interval-size" : "2 hour",
"numb-intervals" : 12
]
},
"cost-map" : {
"PID1": { "PID1": [v1,v2, ... v12],
"PID2": [v1,v2, ... v12],
"PID3": [v1,v2, ... v12] },
"PID2": { "PID1": [v1,v2, ... v12],
"PID2": [v1,v2, ... v12],
"PID3": [v1,v2, ... v12] }
}
}
Randriamasy, et al. Expires April 21, 2016 [Page 16]
Internet-Draft ALTO Cost Calendar October 2015
4.2. Calendar extensions in the Endpoint Cost Map Service
This document extends the Endpoint Cost Service, as defined in
{11.5.1} of [RFC7285], by adding new input parameters and
capabilities, and by returning JSONArrays instead of JSONNumbers as
the cost values. The media type (11.5.1.1} and HTTP method
(11.5.1.2} are unchanged.
4.2.1. Calendar specific input in Endpoint cost map requests
The extensions to the requests for calendared Endpoint Cost Maps are
the same as for the Filtered Cost Map Service, specified in section
XXXX of this draft.
The ReqEndpointCostMap object for a Calendared ECM request will have
the following format:
object {
CostType cost-type;
[JSONBoolean calendared<1..*>;]
EndpointFilter endpoints;
} ReqEndpointCostMap;
object {
[TypedEndpointAddr srcs<0..*>;]
[TypedEndpointAddr dsts<0..*>;]
} EndpointFilter;
4.2.2. Calendar attributes in the Endpoint Cost Map response
The "meta" field of a Calendared Endpoint Cost map response MUST
include at least:
o if the ALTO Client supports cost values for one Cost Type at a
time only: the "meta" fields specified in {11.5.1.6} of RFC 7285
for the Endpoint Cost response:
* "cost-type" field.
o if the ALTO Client supports cost values for several Cost Types at
a time, as specified in [draft-ietf-alto-multi-cost] : the "meta"
fields specified in [draft-ietf-alto-multi-cost] for the the
Endpoint Cost response:
* "multi-cost-types" field.
Randriamasy, et al. Expires April 21, 2016 [Page 17]
Internet-Draft ALTO Cost Calendar October 2015
If the client request does not provide member "calendared" or if it
provides it with a value equal to 'false', then the ALTO Server
response is exactly as specified in the above cited references.
If the ALTO client provides member "calendared" with a value equal to
'true' in the input parameters, the "meta" member of a Calendared
Endpoint Cost Map response MUST include the same addifional member
"calendar-response-attributes" as specified for the Filtered Cost Map
Service. The Server response is thus changed as follows:
o the "meta" member has one additional field
"CalendarResponseAttributes", as specified for the Filtered Cost
Map Service,
o the calendared costs are JSONArrays instead of JSONNumbers for the
legacy ALTO implementation. All arrays have a number of values
equal to 'number-of-intervals'.
4.2.3. Example transaction for the ECS with a routingcost Calendar
Let us assume an Application Client is located in an end sytem with
limited resources and having an access to the network that is either
intermittent or provides an acceptable quality in limited but
predictable time periods. Therefore, it needs to both schedule its
resources greedy networking activities and its ALTO transactions.
The Application Client has the choice to trade content or resources
with a set of Endpoints and needs to decide with which one it will
connect and at what time. For instance, the Endpoints are spread in
different time-zones, or have intermittent access. In this example,
the 'routingcost' is assumed to be time sentitive with values
provided as ALTO Calendars.
The ALTO Client associated to the Application Client queries an ALTO
Calendar on 'routingcost' and will get the Calendar covering the 24
hours time period "containing" the date and time of the ALTO client
request.
For Cost Type 'num-routingcost', the sollicited ALTO Server has
defined 3 different daily patterns each represented by a Calendar, to
cover the week of Monday June 30th at 00:00 to Sunday July 6th 23:59:
- C1 for Monday, Tuesday, Wednesday, Thursday, (week days)
- C2 for Saturday, Sunday, (week end)
- C3 for Friday (maintenance outage on July 4, 2014 from 02:00:00 GMT
to 04:00:00 GMT, or big holiday such as New Year evening).
Randriamasy, et al. Expires April 21, 2016 [Page 18]
Internet-Draft ALTO Cost Calendar October 2015
In the following example, the ALTO Client sends its request on
Tuesday July 1st 2014 at 13:15.
POST /calendar/endpointcost/lookup HTTP/1.1
Host: alto.example.com
Content-Length: [TODO]
Content-Type: application/alto-endpointcostparams+json
Accept: application/alto-endpointcost+json,application/alto-error+json
{
"cost-type" : {"cost-mode" : "numerical", "cost-metric" : "routingcost"},
"calendared" : [true],
"endpoints" : {
"srcs": [ "ipv4:192.0.2.2" ],
"dsts": [
"ipv4:192.0.2.89",
"ipv4:198.51.100.34",
"ipv4:203.0.113.45"
]
}
}
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto-endpointcost+json
{
"meta" : {
"cost-type" : {"cost-mode" : "numerical", "cost-metric" : "routingcost"},
"calendar-response-attributes" : [
{ "calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT,
"time-interval-size" : "1 hour",
"numb-intervals" : 24,
"repeated": 4 }
],
} // end meta
"endpoint-cost-map" : {
"ipv4:192.0.2.2": {
"ipv4:192.0.2.89" : [v1, v2, ... v24],
"ipv4:198.51.100.34" : [v1, v2, ... v24],
"ipv4:203.0.113.45" : [v1, v2, ... v24]
}
}
}
Randriamasy, et al. Expires April 21, 2016 [Page 19]
Internet-Draft ALTO Cost Calendar October 2015
When the Client gets the Calendar for "routingcost", it sees that the
"calendar-start-time" is Monday at 00h00 GMT and member "repeated" is
equal to '4'. It understands that the provides values are valid
until Thursday included and will only need to get a Calendar update
on Friday.
4.2.4. Example transaction for the ECS with a calendar for both
routingcost and latency
In this example, it is assumed that the ALTO Server implements multi-
cost capabilities, as specified in [draft-ietf-alto-multi-cost] .
That is, an ALTO client can request and receive values for several
cost types in one single transaction. An illustrating use case is a
path selection done on the basis of 2 metrics: routing cost and
latency.
As in the previous example, the IRD indicates that the ALTO Server
provides "routingcost" Calendars in terms of 24 time intervals of 1
hour each.
For metric "latency", the IRD indicates that the ALTO Server provides
Calendars in terms of 12 time intervals values lasting each 5
minutes.
In the following example transaction, the ALTO Client sends its
request on Tuesday July 1st 2014 at 13:15.
POST calendar/endpointcost/lookup HTTP/1.1
Host: alto.example.com
Content-Length: [TODO]
Content-Type: application/alto-endpointcostparams+json
Accept: application/alto-endpointcost+json,application/alto-error+json
{
"multi-cost-types" : [
{"cost-mode" : "numerical", "cost-metric" : "routingcost"},
{"cost-mode" : "numerical", "cost-metric" : "latency"}
],
"calendared" : [true, true],
"endpoints" : {
"srcs": [ "ipv4:192.0.2.2" ],
"dsts": [
"ipv4:192.0.2.89",
"ipv4:198.51.100.34",
"ipv4:203.0.113.45"
]
}
}
Randriamasy, et al. Expires April 21, 2016 [Page 20]
Internet-Draft ALTO Cost Calendar October 2015
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto-endpointcost+json
{
"meta" : {
"multi-cost-types" : [
{"cost-mode" : "numerical", "cost-metric" : "routingcost"},
{"cost-mode" : "numerical", "cost-metric" : "latency"}
],
"calendar-response-attributes" : [
{ "cost-type-name : num-routingcost"
"calendar-start-time" : Mon, 30 Jun 2014 00:00:00 GMT,
"time-interval-size" : "1 hour",
"numb-intervals" : 24,
"repeated": 4 },
{ "cost-type-name : num-latency"
"calendar-start-time" : Tue, 1 Jul 2014 13:00:00 GMT,
"time-interval-size" : "5 minute",
"numb-intervals" : 12}
],
} // end meta
"endpoint-cost-map" : {
"ipv4:192.0.2.2": {
"ipv4:192.0.2.89" : [[r1, r2, ... r24], [l1, l2, ... l12]],
"ipv4:198.51.100.34" : [[r1, r2, ... r24], [l1, l2, ... l12]],
"ipv4:203.0.113.45" : [[r1, r2, ... r24], [l1, l2, ... l12]]
}
}
}
When receiving the response, the client sees that the calendar values
for 'routing cost' are repeated for 4 iterations. Therefore, in its
next requests until the routing cost calendar is expected to change,
the client will only need to request a calendar for "latency".
Without the ALTO Calendar extensions, the ALTO client would have no
clue on the dynamicity of the metric value change and would spend
needless time requesting values at an inappropriate pace. In
addition, without the Multi-Cost ALTO capabilities, the ALTO client
would duplicate this waste of time as it would need to send one
request per cost metric.
Randriamasy, et al. Expires April 21, 2016 [Page 21]
Internet-Draft ALTO Cost Calendar October 2015
4.3. Recap of rules related to ALTO Cost Calendars
XXXXX TO BE COMPLETED + MOVED AT THE END OF THE SPECS
A Calendar-aware ALTO Server MUST implement the base protocol
specified in RFC7285.
If no Calendar attributes are defined for a given Cost Type, in a
given resource entry, the ALTO Server MUST set the value in the
'calendar-attributes' array to the symbol 'null' .
When a metric is available as a calendar, it MUST be available as a
single value. An ALTO Server aquiring cost values in limited time
intervals only can construct a single value from the value array.
Calendared information resources MUST be requested via a POST method.
If this member "repeat-indication" is not present in the calendar
attributes indicated in the IRD, it MUST be assumed to have a value
equal to "false".
5. Use cases for ALTO Cost Schedule
[THIS SECTION NEEDS TO BE SHORTENED ]
This section presents use cases showing the benefits of ALTO Cost
calendars for applications needing to decide both "where" to connect
and "when".
5.1. Bulk Data Transfer scheduling upon bandwidth calendars
Large Internet Content Providers (ICPs) like Facebook or YouTube, as
well as CDNs rely on data replication across multiple sites and time
zones to offload the core site and increase user experience through
shorter latency from a local site. Typically the usage pattern of
these data centers or caches follows a location dependent diurnal
demand pattern. In these examples, data replication across the
various locations of an ICP, leads to bulk data transfers between
datacenters on a diurnal pattern.
In the meantime, there is a degree of freedom on when the content is
transmitted from the origin server to the caching node, or from the
core site to a local site. However, scheduling these data transfers
is a non-trivial task as they should not infer with the user peak
demand to avoid degradation of user experience and to decrease
billing costs for the datacenter operator by leveraging off-peak
hours for the transfer.
Randriamasy, et al. Expires April 21, 2016 [Page 22]
Internet-Draft ALTO Cost Calendar October 2015
As a result, these ICPs need to have a good knowledge on the link
utilization patterns between the different datacenters before making
an efficient scheduling decision. While usage data today is already
gathered and used to schedule data transfers, provisioning these data
gets increasingly complex with the number of CDN nodes and datacenter
operators that are involved. In particular, privacy concerns prevent
that this kind of data is shared across administrative domains. The
ALTO Cost Calendar avoids these problems by presenting an abstracted
view of time sensitive utilization maps through a dedicated ALTO
service to allow ICPs a coherent scheduling of data transfers across
administrative domains and time zones.
Likewise, bandwidth Calendaring allows network operators to reserve
resources in advance according to agreements with their customers,
enabling them to transmit data with specified starting time and
duration, for example, for a scheduled bulk data replication between
data centers. Traditionally, this can be supported by a Network
Management System operation such as path pre-establishment and
activation on the agreed starting time. However, this does not
provide efficient network usage since the established paths exclude
the possibility of being used by other services even when they are
not used for undertaking any service.
An ALTO Cost calendar for TE metrics on transfer paths can support
the scheduled bulk data replication with better efficiency since it
can alleviate the processing burden on network elements.
Cost calendars for these time-sensitive ALTO TE metrics need to
consider the network topology and the dynamicity of the traffic. For
example, a small topology with low density and low capacity that
carries inpredictable, heavy and bursty traffic has few chances to
exhibit stationary TE metric value patterns over large periods and
would benefit to use the ALTO Calendar over smaller time slots. Some
ALTO TE metric values, even aggregated over time may need to be
updated at a frequency that would require doing ALTO requests at a
pace that would be overload both the ALTO Client and the Server.
Large high capacity topologies would benefit from Cost Calendars with
a coarse time granularity for the filtered cost map service where as
Calendars of finer time granularity for the Endpoint Cost Service
would be better suited for small low density and capacity topologies.
5.1.1. Applicable example transaction
Assuming a Large high capacity topology, an applicable example
transaction for this us case is provided by section 4.1.3. "Example
transaction for a FCM with a "request-date" bandwidth Calendar".
Randriamasy, et al. Expires April 21, 2016 [Page 23]
Internet-Draft ALTO Cost Calendar October 2015
5.2. Applications with limited connectivity or access to datacenters
Some applications are limited in their connectivity either in time or
resources or both. For example applications running on devices in
remote locations or in developing countries that need to synchronize
their state with a data center periodically, in particular if
sometimes there is no connection at all. Example applications are
enterprise database update, remote learning, remote computation
distributed on several data center endpoints.
Wireless connections have a variable quality and may even be
intermittent. On the other hand, the wireless network conditions
have a rapid impact on applications while they can sometimes be
predicted over a span of time. Non real time applications and time-
insensitive data transfers such as client patching, archive syncing,
etc. can benefit from careful scheduling. It is thus desirable to
provide ALTO clients with routing costs to connection nodes (i.e.
Application Endpoints) over different time periods. This would allow
end systems using ALTO aware application clients to schedule their
connections to application endpoints.
Another challenge arises with applications using data and physical
resources scattered around the world. For non-real time
applications, the interaction with Endpoints can be orchestratrated
and scheduled at the time slots corresponding to the best possible
network conditions. For instance, resource Ra downloaded from
Endpoint EPa at time t1, Resource Rb uploaded to EPb at time t2, some
batch computation involving Ra and Rb done on EPc at time t3 and
results R(A,B) downloaded to EPd and EPe at time t4.
+-----+ +-----+
| EPa | | EPb | <----- Rb
+-----+ +-----+ (t2=50)
| +-------+ |
Ra --------------> | EPc | |
(time t1=10) | | |
|t3=100 | <----------------- Rb
+-------+
| \
| \
R(Ra,Rb)
(t4=200)
| \
| -------------------.
V V
+-----+ +-----+
| EPd | | EPe |
+-----+ +-----+
Randriamasy, et al. Expires April 21, 2016 [Page 24]
Internet-Draft ALTO Cost Calendar October 2015
5.2.1. Applicable example transaction
An applicable example transaction for this use case is provided by
section 4.2.3. "Example transaction for the ECS with a "periodic"
routingcost Calendar".
5.3. SDN Controller guided traffic scheduling with Calendars
An ALTO Server can assist an SDN Controller by hosting abstracted
network information that can be provided to SDN aware applications
via an ALTO Client.
Via the Northbound interface (NBI), applications may get QoE
impacting information such as network provider preferences w.r.t.
delay and bandwidth on the network paths. Such information may be
provided via the ALTO Service.
One key objective of an SDN controller is the ability to balance the
application traffic whenever possible. Resources availability may
often be predicted and strong incentives for applications to time
shift their traffic may be given by network operators appropriately
setting routing cost values at different time values, according to
their policy on network utilization over time.
To achieve this objective, the SDN controller can:
1. get the network state information from its controlled network
elements through its southbound API and derive an estimation of
these values over given time frames
2. abstract the network topology and end to end path costs and store
them in an ALTO Server as Network Maps and Cost Calendars
3. deliver these values to ALTO Clients linked to SDN applications,
through the NBI.
This way:
o On one hand, the applications get the best possible QoE, as they
can pick the best time for them to access one or more Endpoints or
PIDs,
o One the other hand, the SDN controller achieves load balancing and
optimizes application traffic as it may guide the application
traffic so as to better distribute the traffic over time.
Randriamasy, et al. Expires April 21, 2016 [Page 25]
Internet-Draft ALTO Cost Calendar October 2015
5.3.1. Applicable example transaction
An applicable example transaction for this use case is provided by
section 4.2.4. "Example transaction for the ECS with a calendar on
both routingcost and latency".
6. IANA Considerations
Information for the ALTO Endpoint property registry maintained by the
IANA and related to the new Endpoints supported by the acting ALTO
server. These definitions will be formulated according to the syntax
defined in Section on "ALTO Endpoint Property Registry" of [RFC7285]
,
Information for the ALTO Cost Type Registry maintained by the IANA
and related to the new Cost Types supported by the acting ALTO
server. These definitions will be formulated according to the syntax
defined in Section on "ALTO Cost Type Registry" of [RFC7285],
6.1. Information for IANA on proposed Cost Types
When a new ALTO Cost Type is defined, accepted by the ALTO working
group and requests for IANA registration MUST include the following
information, detailed in Section 11.2: Identifier, Intended
Semantics, Security Considerations.
6.2. Information for IANA on proposed Endpoint Propeeries
Likewise, an ALTO Endpoint Property Registry could serve the same
purposes as the ALTO Cost Type registry. Application to IANA
registration for Endpoint Properties would follow a similar process.
7. Acknowledgements
Thank you to Diego Lopez, He Peng and Haibin Song and the ALTO WG for
fruitful discussions.
8. References
8.1. 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>.
Randriamasy, et al. Expires April 21, 2016 [Page 26]
Internet-Draft ALTO Cost Calendar October 2015
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693,
DOI 10.17487/RFC5693, October 2009,
<http://www.rfc-editor.org/info/rfc5693>.
8.2. Informative References
[draft-ietf-alto-multi-cost]
S. Randriamasy, W. Roome, N. Schwan, , "Multi-Cost ALTO
(work in progress), draft-ietf-alto-multi-cost", May 2015.
[draft-wu-alto-te-metrics]
Q. Wu, Y. Yang, Y. Lee, D. Dhody, S. Randriamasy, , "ALTO
Traffic Engineering Cost Metrics (work in progress)",
October 2014.
[draft-yang-alto-topology]
Y. Yang, , "ALTO Topology Considerations (work in
progress)", July 2013.
[ID-alto-protocol]
R.Alimi, R. Penno, Y. Yang, Eds., "ALTO Protocol, RFC
7285", September 2014.
[RFC7285] R. Alimi, R. Yang, R. Penno, Eds., "ALTO Protocol",
September 2014.
[sdnrg] "Software Defined Network Research Group,
http://trac.tools.ietf.org/group/irtf/trac/wiki/sdnrg".
[slides-88-alto-5-topology]
G. Bernstein, Y. Lee, Y. Yang, , , "ALTO Topology Service:
Use Cases, Requirements and Framework (presentation slides
IETF88 ALTO WG session),
http://tools.ietf.org/agenda/88/slides/
slides-88-alto-5.pdf", November 2013.
Authors' Addresses
Sabine Randriamasy
Alcatel-Lucent Bell Labs
Route de Villejust
NOZAY 91460
FRANCE
Email: Sabine.Randriamasy@alcatel-lucent.com
Randriamasy, et al. Expires April 21, 2016 [Page 27]
Internet-Draft ALTO Cost Calendar October 2015
Richard Yang
Yale University
51 Prospect st
New Haven, CT 06520
USA
Email: yry@cs.yale.edu
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
Lingli Deng
China Mobile
China
Email: denglingli@chinamobile.com
Nico Schwan
Thales Deutschland
Email: nico.schwan@thalesgroup.com
Randriamasy, et al. Expires April 21, 2016 [Page 28]
