Application to QoS Requirements
F. Armando
, N. Van Wambeke
, C. Chassot
, E. Exposito
and K. Drira
Université de Toulouse / INSA – Toulouse – France
Keywords: Dynamically configurable transport protocol, Policy-based management, QoS provisioning, model-based
Abstract: Self-adaptation of communication protocols is a major issue in the conception of future QoS-oriented
services for the ambient Internet. Our approach is based on behavioural and architectural adaptation
properties of dynamically configurable Transport protocols. This paper proposes an architecture for the QoS
provisioning at the Transport level. To fulfil this provisioning, the decision process follows a policy-based
framework, using different external models in order to have an extensible design. We illustrate the use of
this framework in a case study for the QoS optimization of a mobile user, roaming from a wired network to
a wireless network.
Recent advances in computing and wireless
networking technologies allow considering the
deployment of complex wireless, mobile and
cooperative applications within a fully pervasive,
mobile and heterogeneous Internet. For instance,
military emergency operation management systems
are a typical example of such applications. They
support mobile users cooperating applications for
crisis management in linked to variable
communication resources that change depending on
the investigated field, the role of the participants in
the operation, etc.
From a communication point of view, multiple user
and application time-varying requirements have to
be satisfied. They depend on the communication
tools used by the participants (e.g. interactive
audio/video, sms ...); they also depend on the
evolution of the activity which can make it different
the interactions (e.g. nature, priority) between the
participants, for instance when one of them
discovers a critical situation. By the way, multiple
time-varying constraints (e.g. power, bandwidth) are
also to be considered, depending on machine and
network resources which are used by the
In such a complex and dynamic context, future
communication systems are expected to have
behavioral and architectural self-adaptation
properties, aimed at tackling different kinds of
dynamic requirements, still considering dynamic
constraints associated with the network/machine
Accordingly, several solutions have already been
proposed in the literature; they differ in several
points related to the targeted goals (e.g. QoS,
security …), the addressed levels (Application,
Transport …), the adaptation actions and their
properties. Particularly, protocols whose internal
architecture may be dynamically composed appear
to be very suitable for both behavioral and
architectural self adaptation (Bridges et al., 2001,
Exposito et al., 2003, Mocito et al., 2005, Wong et
al., 2001). Our approach is based on adaptation of
such protocols at the end-to-end level (Transport
level - TCP level -and above). The goal is to match
as best as possible dynamic application QoS
requirements, while taking into account network
resource and context changes.
Dynamic configuration of adaptive protocols raises
different classes of problems that we address for the
Transport level adaptation.
Problem 1: Design and evaluation of new Transport
mechanisms and protocols, allowing optimizing a
given QoS requirements with regard to the network
resource constraints.
Armando F., Van Wambeke N., Chassot C., Exposito E. and Drira K. (2007).
In Proceedings of the Second International Conference on Wireless Information Networks and Systems, pages 259-267
DOI: 10.5220/0002151202590267
Problem 2: Elaboration of provisioning rules for the
selection and adaptation of the Transport
mechanisms to be (re)composed / (re)parameterized.
A major difficulty, without generic solution at the
current time, is to ensure coherency of the
composition / parameterization choices, both within
and between the considered adaptation levels.
Tackling these needs by means of informal models
may lead to non generic or suboptimal solutions due
to the complexity of the problem. In front of this
limit, formal model-based design constitutes a
promising approach (Farkas et al., 2006,
Landry et al.,
2004), particularly studied in our work for
architectural self adaptation at different levels of the
end-to-end communication stack (application,
middleware and transport levels) (Chassot et al.,
2006a). In (
Van Wambeke et al., 2007), we propose an
analytical model aimed at helping the decision
process at the Transport level was designed.
Problem 3: Design of an architecture for the
provisioning process, and then the enforcement of
the operational rules on the active communication
elements (e.g. adaptive Transport protocols).
It is the major goal of the NETQoS project to design
such architectures. The proposed approach starts
from the policy-based network management
(PBNM) model, which is extended to reach several
management of several kinds of actor’s policy:
operator, service provider, user and
dynamic adaptation, not only at the network
level but also at the Transport level.
The main contribution of this paper has been
performed within the NETQoS project, and mainly
deals with the third problem exposed hereafter. We
present a framework for a model-based provisioning
and enforcement of configuration / adaptation rules
for adaptive Transport protocols. This framework is
then illustrated with a case study.
The rest of the paper is structured as follows.
Section 2 describes related work. Section 3 describes
the elements of the framework and the provisioning
process. Section 4 provides details about the
elaborated models for Transport-level adaptation.
Section 5 provides a case study illustrating the
provisioning process within the proposed
framework. Section 6 provides conclusion and future
There are many existing solutions for context
adaptation. A complete study and classification can
be found in one of our previous works (
Chassot et al.,
2006b). In what follows, this classification is
summarized and dynamically configurable transport
protocols are presented.
2.1 Classification of Context
Adaptation Solutions
Adaptation objectives, techniques and properties are
among the main facets of adaptability. They are
studied and classified in this section.
2.1.1 Adaptability Objectives
Adaptability targets several objectives. QoS aspects
such as connectivity or access bandwidth issues in
roaming are considered in (
Kaloxylos et al, 2006). End
to end QoS optimization in the Best Effort Internet
makes heavy use of adaptation techniques (Akan and
Akyildiz, 2004). Security in wireless networks, such
as firewalls activation and deactivation, can also
benefit from adaptability (Perez and Skarmeta,
2004). Resources optimization related to device
power, computation or storage capability are
presented in (
Marshall and Roadknight, 2001).
2.1.2 Adaptation Techniques
Adaptation techniques target all layers of the OSI
Application layer – (
Wu et al., 2001) addresses
adaptation of video streaming applications for the
Best-Effort Internet. The proposed techniques are
based on two mechanisms: an applicative congestion
control (rate control, rate-adaptive video encoding)
and time aware error control with FEC.
Middleware layer - Reflexive architectures such as
OpenORB or Xmiddle (
Capra et al., 2003) are good
supports for adaptation as they allow run-time
modification of the architecture.
Transport layer - TCP’s congestion control is a
well-known adaptation example. The IETF DCCP
protocol allows users to choose the congestion
control. SCTP targets adaptation to network failures
using multi homed associations. (Akan and
Akyildiz, 2004) studies various types of mobile
applications in wireless Internet. Adaptation consists
in parameterization of congestion control
mechanisms using context information. (Bridges et
al., 2001, Exposito et al., 2003, Mocito et al., 2005,
WINSYS 2007 - International Conference on Wireless Information Networks and Systems
Wong et al., 2001) study the architectural adaptation
of transport protocols by dynamic composition of
protocol modules. Next section (2.2) is dedicated to
these frameworks illustrating the modular
architecture concept targeted by our work.
Network layer – (
DaSilva et al., 2004) addresses
QoS-aware routing problems within ad-hoc mobile
networks. In (Wong et al., 2001), dynamic and
secure provision of IP services for military
wired/wireless networks is considered. In a policy-
based networking management context, the need for
self-adaptation is considered in (
Samaan and
Karmouch, 2005)
, using a learning-based approach.
MAC layer - The solutions handle connection and
access QoS problems for mobile users using
different terminals and roaming protocols. (
et al., 2006) provides a solution for optimizing the
handover latency but the other QoS requirements are
not considered.
2.1.3 Adaptation Properties
The adaptation solutions suggested in the literature
are defined in various ways.
The adaptation is behavioral when the execution of
a service can be modified without modifying its
structure. TCP and specific protocols such as the
ones in (Akan and Akyildiz, 2004) provide
behavior-based adaptation. It is easy to implement
but limits the adaptability range. Indeed, the addition
of new behaviours requires the component to be
recompiled and the adaptation can no longer be
performed during run-time.
The adaptation is architectural when the structure of
adapting services can be modified. The replacement
of a component by another can be implemented
following a plug and play approach where the new
component has the same interfaces as the replaced
Finally, adapting components can reside on a single
machine or be distributed. In the first case,
adaptation is vertical and changes are performed
only locally. In the second case, it is horizontal and
synchronization between peer adapting entities has
to be managed.
2.2 Dynamically Configurable
Protocol Architectures
Dynamically configurable protocol architectures are
based on the protocol module concept. A protocol
module is a primitive building block (
Hutchinson and
Peterson, 1991)
resulting from the decomposition of
the protocol’s complexity into various successive
elementary functions. A protocol is then viewed as
the composition of various protocol modules in
order to provide a global service.
These architectures can be refined into two different
categories depending on their internal structure: the
event based model (followed by Coyote and Cactus)
and the hierarchical model (X-Kernel (
Hutchinson and
Peterson, 1991) and APPIA). ETP follows an hybrid
approach combining both models (Exposito, 2003).
These protocol architectures appear as a good choice
for future communication protocol’s self-adaptation
as they are capable of run-time architectural
adaptation, meaning that the modules composing
them can change during the communication. This
run-time architectural adaptation raises many
problems such as: (1) synchronization of adapting
peers; and (2) the choice of the best composition
guided either by the user’s requirements or by the
modification of the context.
The NETQoS IST project is addressing the problem
of QoS in IP Networks from Policy based network
management architecture, to provide flexible and
adaptive end to end QoS provision, unlike number of
solutions provided by bottom-up approach. The
NETQoS system introduces the notion of predefined
policies as a promising solution to address the needs
of QoS traffic management.
In order to address the policy based QoS
management, policy architecture was defined.
Policies prescribe a set of rules based on the
users/application requirements, which are
transformed into high level network level policies.
Since the network level-policies are derived from
business objectives, users and applications
requirements described in the SLA, these policies
have to evolve and to be adapted to the changes in
these objectives and requirements in a timely
manner. An autonomous self-adaptable policy-based
management framework with inherent dynamic
capabilities to best manage, customize and extend
the underlying complex infrastructure of
communication systems resources in response to the
continuously changing business objectives and users
requirements, is the main goal of the NETQoS
project. The enforcement policies thus generated are
translated into network device dependent rules to
configure the network
Application to QoS Requirements
3.1 The framework for Dynamic Policy
The general architecture of the NETQoS system
distinguishes four main entities or systems (Fig. 1):
the Policy Description (PD) implements a set of
ontologies used to specify the actor-level
policies, the operational policies, etc;
the Actor Preference Manager (APM) provides
NETQoS GUI/API allowing users to define
actor-level dynamic policies to the NETQoS
system based on ontologies. These policies
(e.g. requirements, preferences, profile,
quality reporting…) may be expressed before
or during the communications;
the Automated Policy Adaptor (APA) is the
central entity of the NETQoS system. It does
not provide QoS by itself, but provides and
dispatches operational policies (namely
Network and Transport level policies) that
allow the communication system to take into
account the actor-level dynamic policies;
the Monitoring and Measurement (MoMe)
implements all the monitoring and
measurement tasks associated with: (1)
context evolution, e.g. actor’s policies
evolving, end systems/network resource
changing …; and (2) evaluation of the
operational policy efficiency and the reporting
of quality information to the actors.
Acto rs policy
re pository
Con text M an ag e r
Polic y Enf o rce ment MG
Policy Decision MG
Context Repository
Transport PDM
Ne t w o r k P D M
Multi level
decis ion
Transport PEM Network PEM
MoMe Manager
P oli cy Adap tor MG
Operation al Policy
Repo sito ry
Policy Descriptio n
Communication link
MoMe Tool
Figure 1: The general NETQoS architecture.
3.1.1 The Automated Policy Adapter
The APA is aimed at deciding, dispatching and
adapting the operational policies that allows the
communication system to take into account the
actors' level dynamic policies taking into account the
context evolving. The APA is composed of three
main components:
the Policy Decision Manager (PDM) has in
charge deciding the set of operational policies
that implements the actor-level policies. This
mapping may change depending on context-
related information;
the Policy Enforcement Manager (PEM) has in
charge the deployment of the policies decided
by the PDM on their Network/Transport-level
enforcement points;
the Policy Adaptation Manager (PAM) has in
charge the adaptation of policies, individually
or by grouped, when the success criteria
associated with a policy is not reached.
Policy decision manager
. The PDM is aimed at
deciding an optimal set of policies to be settled at
the Network and/or at the Transport level to satisfy
the set of actor-level policies. This policy
provisioning may be performed using rules taking
into account the dynamicity of the actor’s policies
and changes in the context information; these rules
are elaborated using a model-based approach (see
section 3.3.2). The policy provisioning may lead to
policy conflicts that the PDM has to solve, for
instance when actor-level policies cannot be reached
as required.
Each time the PDM decides a (new) operational
policy, it provides the corresponding rules to the
PEM. If the policy is enforceable, the PDM informs
the PAM of the enforcement of a new policy.
Policy enforcement manager
. The PEM is in charge
of dispatching the operational policies decided by
the PDM to the actual policy enforcement point
(PEP). For instance, for a Transport level adaptation,
the PEM dispatches the Transport protocol
configuration rules to be applied on the end nodes.
The PEM is independent of the Network and
Transport technologies that are used to really
enforce the policies, i.e. the PEM provides the rules
to be performed in a language that is independent of
the ones used by targeted QoS-oriented
communication system. Consequently, the PEM
provides generic interfaces allowing the different
entities to communicate with the actual PEP, and
adaptors have to be implemented, for instance on the
PEP themselves, to translate the generic PEM rules
into specific technology-dependant rules.
Policy adaptation manager.
The PAM has in charge
the adaptation of a policy when its success criteria
are not reached. The PAM may decide to adapt the
policy or an associated subset of relevant policies.
When adaptation is not possible, the PDM is
informed of the current policy failure, possibly
associated with a diagnosis.
The PAM mainly acts in the following situations:
WINSYS 2007 - International Conference on Wireless Information Networks and Systems
when the PAM is informed by the PDM that a
new operational policy is enforced, the PAM
stores the policy in the operational policy
repository together with some success criteria
(e.g. end-to-end packet loss must be smaller
than 5%).
when the PAM receives alarms from the
MoMe, it tries to adapt the failed policy and
informs the PDM of the result.
3.3.2 Policy Provisioning
Two different policy enforcement levels are
considered: the transport level and the network level.
For both levels, policy provisioning deals with the
way the operational policies are elaborated, selected
and adapted.
This process is complex as it requires knowledge of
many context aspects such as access network or
actors’ preferences. The component that performs
policy provisioning is the central element of the
NETQoS framework.
Various techniques exist for the provisioning
process. The simplest one consists in having a set of
predefined rules which are hard coded into the
deciding component producing a set of predefined
responses that depend on the environment. The main
aspect (among many others) that makes this simple
technique inefficient is its lack of extensibility.
Indeed, being hard coded, the policies that manage
the decision process are not changeable during run-
In order to have an extensible decision process, it is
possible to guide it using different external models
such graph-based models presented in (
Chassot et al.,
where all aspects of communication can be
represented and the different evolutions of the
system are characterized as elements of a graph
grammar. In such models, the adaptation is thought
ahead of time providing fast response to changes.
Moreover, these models can be stored in an external
repository and may change during the
communication. By doing so, the set of responses
that the decision component may have is not
statically predefined at design-time and can be
further extended by refining the models that manage
the system evolving during run-time.
Moreover, different models can be used at different
abstraction levels. Hence, the cooperation and
interaction description can be implemented by a
labelled and directed graph model that may be
transformed following a set of graph grammar rules
into a transport connection model. At the transport
level, specialized models such as analytical models
can be used in order to get a policy response which
is best suited to the environment while taking both
actor requirements and preferences into account.
In the NETQoS system, the component in charge of
this decision process is the APA. Various sub
components take place in this provisioning process,
the PDM is responsible for performing the
provisioning. The PAM then takes the necessary re-
provisioning actions in order to perform adaptation.
1) Provisioning. In order to perform provisioning at
the Transport and Middleware levels, policies in
place at the network level have to be known. Due to
this constraint, the natural order for the provisioning
consists in initially performing network provisioning
prior to transport provisioning. Once these two steps
are done, middleware provisioning can start.
2) Adaptation. Once the adequate communication
services have been selected and deployed, specific
adaptation actions are performed in order to
maintain the QoS required. The adapting conditions
are expressions based on the current media flows
and applications regarding the QoS goals computed
during the decision process. One possibility is to
adapt the middleware level first then the transport
level and finally the network level.
3.3.3 Policy Provisioning Process
In order to perform provisioning at both the network,
transport and middleware levels, the PDM
component has been divided in two different
components that are responsible for (N-PDM)
network level provisioning, (T-PDM) transport level
provisioning and (M-PDM) middleware level
The policy provisioning process can be lead using
different models at these various levels. In order to
support this adaptation, various architectures are
possible. The configuration and outsourcing models
defined by the IETF (Boyle et al., 2000) are suitable
for such task.
For instance, for an interactive and high priority
flow, a network service characterized by low delay
and high reliability could be selected in a first time
(e.g. EF service). In a second time the selection of a
basic UDP transport service without additional
middleware mechanisms would be enough to
guarantee the satisfaction of the user. In contrast, if
the EF service has not been declared as available for
this user (e.g. following the service provider
policies), a Best-Effort network service could be
selected, combined with an UDP or DCCP transport
service and completed with an error control
mechanism implemented at the middleware level.
Application to QoS Requirements
The design can be done as illustrated by the figure 2
below. In this architecture, the outsourcing model is
followed; the PDM component represents any of the
N-PDM, T-PDM or M-PDM. The decision is not
directly performed by the PDM but it is delegated to
external modules (represented by squares on the
diagram). In each of these modules, a specific
decision algorithm is implemented in order to
construct a potentially partial policy. The successive
invocation of various modules (TD...ND) will lead
to a valid policy being generated.
For each of the outsourced modules, the access
method can be of any kind (from simple RPC to
XML/SOAP Web Services). This design
architecture allows easy extension of the system by
simply adding new decision components. By such,
any new model that is produced by the different
actors (Operator/Service provider) can be deployed
and used without requiring modification of the PDM
itself. The PDM acts here as a system kernel
managing the process by delegating tasks to the
various external elements successively.
Figure 2: Policy provisioning process architecture.
The above figure presents an outsourcing based
model for the PDM decision process. When
necessary (e.g. when a new connection is to be
established in the NETQoS domain), the PDM
retrieves the information regarding the actor
preferences and associated policies from the
repositories. These policies contain information that
allows the PDM to contact the appropriate software
module to perform the decision. Technologies such
as RMI, Web Services or CORBA may be used for
this task. As this software module is external to the
PDM, this model is largely extensible by the simple
addition of new modules and simply describing them
in the repositories. This action also allows users to
choose and classify the adaptation actions provided
by these new modules in their preferences.
In order to support different interfaces, the
invocation takes place in two stages. Stage 1 allows
for discovering the parameters required by the
outsourced modules (i.e. inputs to the decision
model they hold inside). The PDM is then
responsible for retrieving the necessary information
from the other components in the NETQoS system
(e.g. MoMeTool or Context Manager). Once these
parameters have been retrieved, the outsourced
decision service can be invoked by the PDM
returning the decided policy. The PDM could then
continue invocation following the users' preferences
(i.e. perform adaptation both at Middleware and
Network levels simultaneously) which would lead to
further modification of the policy being decided
upon. At the end of this process, the PDM has
constructed the policy to be activated and deployed
in order to support the new communication. This
decision is then transmitted to the PAM and PEM in
order for them to take the necessary actions to
respectively, monitor and react to adaptation needs
by enforcing and deploying the policy via the PDPs.
4.1 Adaptation at the Transport Level
Transport-level adaptation consists in dynamically
selecting and adapting parameters and/or internal
architecture of the adaptive Transport protocol used
to transfer an application data flow. The goal is to
match as best as possible dynamic and hierarchical
requirements, i.e. an actor’s policy, associated to a
given application, taking the current communication
context (e.g. access networks used by the terminals
hosting the applications):
the processing of an actor’s policy, typically a
user’s policy for a given application when this
one is launched, may lead to Transport-level
adaptation for the connection underlying this
application only. It may also lead to
Transport-level adaptation for other
connections when hierarchical relationships
(e.g. priorities) have been defined between the
actor’s policies, for instance when a user has
defined priorities between his/her
the communication context may evolve
depending on several factors, for instance
when the hosting terminal is moving from an
access network to another.
WINSYS 2007 - International Conference on Wireless Information Networks and Systems
To handle dynamic and hierarchical policies,
together with an evolving communication context,
two kinds of Transport policies, namely per
connection handling, and per group of connections
handling, may be applied:
per connection handling means that the
adaptation rules are applied independently,
connection per connection;
per group of connections handling means that
several connections may be coordinated by the
adaptation rules, allowing taking into account
hierarchical policies, for instance expressed by
a user on his/her applications.
Both policies are refined in operational rules that
consist in composition and parameterization rules of
the transport protocol implementing each
4.2 The Proposed Models for Policy
In what follows, a model for automatically selecting
the best composition of protocol modules at the
transport/middleware level is presented. This model
has been previously presented in (
Van Wambeke et al.,
and is only briefly recalled here.
We model a protocol module (A) by the following
A =
[ A
Given this description, we are able to describe a
valid composition as respecting the following
Additionally, for each module, efficiency vectors are
defined which allow for evaluating the module’s
efficiency in the various contexts that are
Based on the above, the decision process comes to
solving the following optimization problem:
The additional constraints are produced by the
refinement of the policies. For example, a user might
specify that he is using a low memory device which
would be refined into a constraint that limits the
number of unused variables production.
5.1 Scenario Description
This scenario aims at illustrating Transport
adaptation by instantiating the above presented
model in the decision process.
For this scenario, let’s assume that
the users terminal and the server are connected
to high speed wired access networks,
interconnected by a Best Effort Internet
the user's policies (applicable to the present
context) are as follow:
“when I'm on a wired connection, I would
rather have ensured QoS of Gold quality
for all my applications”;
“when I'm on a wireless network, I would
rather have my communications classified
by decreasing level of quality
requirements as follow: Audio call, Video
call, VoD movie, Internet Radio, Web,
Mail and similar, File transfers”.
While the user is connected to the wired network,
the service provider's policies are such that the
maximum amount of bandwidth that the user might
use is 10 Mbps, thus, resource reservations will be
performed and updated until this limit is reached.
Note that these reservations are handled by any QoS
system in place such as the one proposed in the IST
FP6 EuQoS project.
Let’s now assume that:
at t = t0, the user starts to work at his office
at t = t1 > t0, the user disconnects his laptop
and the wireless interface becomes the default
interface (this is handled by the OS itself).
5.2 Interaction of Policy Actors and
NETQOS Components
The NETQoS components that are involved in this
scenario are:
otherwise 0
i variablerequiresA if 1
otherwise 0
i variableproducesA if 1
Application to QoS Requirements
MoMe (Monitoring and Measurement): Context
Manager (CM) and MoMeTool,
APA (Automated Policy Adapter): PDM, PEM
and PAM (for the Transport only, i.e. adaptation
at the network level is not considered in this
REPO (Policy Repository).
The following illustrate the main scenario steps.
1) At the NETQOS system initialization, the APA
subscribes to the CM for a set of events: application
launch, policy violation, context modification etc.
2) A t = t0, the launch of various applications is
detected by the CM; for each one:
the CM informs the PDM that an application is
the PDM retrieves from the REPO the policies
related to the identified user and application;
these policies contain information that allows
the PDM to contact the appropriate external
software module that decides the
Middleware/Transport protocol configuration
to be selected with regard to the policy
defined for the ftp application;
the PDM contacts the outsourced software
module, and provides it with the necessary
information to decide the rules to be applied;
the appropriate rules for Transport protocol
configuration are returned to the PDM by the
outsourced software module following the
model presented above;
those rules are then transmitted to the PAM and
PEM in order for them to take the necessary
actions to respectively, monitor and react to
adaptation needs and enforce and deploy the
policy via the PEP at the Transport layer;
if the MoMeTool, via the CM informs the PAM
that success criteria associated to the selected
policy are no longer met (via alarms); the
PAM may try to adapt the policy and may also
inform the PDM if necessary. For instance, the
adaptation action can consist in changing
parameters of the micro-protocols.
3) A t = t1, the change of network context is detected
by the CM
the CM informs the PDM that the user is
moving to a different network;
the PDM retrieves from the REPO the policies
related to the identified user and application
for the new context; these policies contain
information that allows the PDM to contact
the appropriate external software module that
implements the model presented in the
previous section in order to decide on the
Middleware/Transport protocol configuration
to be selected with regard to the policy
defined for the currently running applications.
At this step, two possibilities may be
the outsourced software module provides
the PDM with the set of rules that can be
applied for the application;
taking into account its current execution
context (here, various active applications
for which the QoS requirements have
changed), the PDM/PAM selects the
Transport protocol configuration /
adaptation to be applied for each
the appropriate rules for Transport
protocol configuration/adaptation for the
new connection and possibly existing
connections are returned by the
outsourced software module;
those rules are then transmitted to the
PAM and PEM in order for them to take
the necessary actions to respectively,
monitor and react to adaptation needs and
enforce and deploy the policy via the PEP
at the Transport layer;
if the MoMeTool, via the CM informs the PAM
that success criteria associated to the selected
policy are no longer met (via alarms); the
PAM may try to adapt the policy and may also
inform the PDM if necessary.
When an application is stopped, the PAM and PDM
may also apply reconfiguration actions.
In this article, we presented a framework for the
dynamic configuration of adaptive Transport
protocols in order to support policy-based QoS
provisioning for heterogeneous, mobile and
cooperative activities in a pervasive Internet. The
main components of the general policy architecture
have been described, especially the APA
component, responsible for the policy decision
process of adaptation actions, in particular at the
Transport level. A case study aimed at displaying the
framework’s usage and internal interactions in the
case of mobile, multi-network, continuous, seamless
communications has been presented. The models
which govern the policy-based decision and
WINSYS 2007 - International Conference on Wireless Information Networks and Systems
provisioning process have been illustrated in this
Future works on the topic include, but are not
limited to, the implementation of the presented
framework. Moreover, evaluation of the efficiency
of the different mechanisms that compose the
current architecture has to be carried on.
Part of this work presented has been carried on as
part of the European IST FP6 NetQoS project. In
conjunction with this, several aspects of this works
are funded by DGA grant.
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