Flat-rate pricing is widely
used in the current Internet because it is simple and predictable. However,
with the Internet evolving into a multi-service network, an effective and
efficient QoS pricing scheme has to be developed in order to provide QoS
differentiation. Currently, two QoS architectures: Integrated Services and
Differentiated Services have been standardized by the IETF to support QoS in
the future Internet. Due to the inherent scalability problem of the IntServ
approach, it is generally believed that DiffServ is more likely to be
implemented in the Internet core. It is generally believed that a practical
approach for End-to-End QoS is to implement DiffServ in the core and IntServ
at access. Unlike IntServ, which can charge users based on the allocated
resources, pricing for DiffServ networks is more complicated and has drawn a
lot of attention in the networking community. So far, a lot of researches
have been done in this area but there hasn't been a widely accepted solution
yet.
In this project, we
investigate various aspects of pricing in DiffServ networks:
1) Economic Efficiency:
Since pricing itself is a
economic problem, how to achieve economic efficiency is very important. Many
optimal pricing schemes have been proposed to address this issue. Most of
approaches assume a known user utility function and establish a optimization
model to either maximize the user benefit or provider revenue. However, the
major problem with this kind of approach is that user utility function can
not be well defined in short term and sometimes even very difficulty in long
term. The effectiveness of such schemes is still questionable. An
alternative is to create a market environment and let users bid for the
network usage. This type of approach does not assume a known user utility
function and achieves economic efficiency perfectly. However, the
implementation overhead is quite significant in this case. In this project,
we examine the possibility of using some simple and practical pricing
strategies and the level of economic efficiency it can achieve.
2) Simplicity
Although economic efficiency
has been the main focus for a lot of studies, many researchers believe that
optimal pricing can not be achieved in practice and suggest that we should
emphasize the implementation issues. Those issues include what is the
architecture framework, how to collect information for the price setting,
how to exchange the price information once the price is set, how complex the
architecture is, and how scalable the architecture is. We believe a flexible
and scalable architecture is crucial especially when the scale of the
problem is of the Internet. In this project we propose a tariff-based
framework which address these issues in particular.
3) Quality of Service
Last but not the least is the
Quality of Service aspect. Since price is such an important economic
incentive to the users, it is often considered as an effective mechanism for
traffic management. Indeed, many proposed pricing schemes entail either
congestion control or admission control or even both. In this project, we
first have a close look at the relationship between pricing and these two
traffic management functions and integrate pricing and admission control
into the framework to achieve better QoS.
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The key design choices we
made during the development of our framework are:
-
Decouple the pricing for core
from End-to-End pricing. This is due to the following two reasons:
-
Mixture of various QoS
technologies
-
Involvement of many service
providers
-
Instead of focusing on
congestion cost, we set the price to reflect the resource availability
inside the network.
This is due to the
consideration that it is more desirable to tie pricing with admission
control in a DiffServ environment because we want proactive control rather
than reactive behavior such as congestion control in order to support the
QoS guarantee or improve the level of QoS. Furthermore, since pricing
induces admission control automatically, using price as a primary admission
criterion seems very promising.
-
Maintain a global price table
at the access. This is due to the following three considerations:
-
DiffServ aims to keep core
elements simple
-
Reduce per-flow based
messaging overhead
-
Push the admission control to
the edge
To address the scalability
issue, we use the concept of domain abstraction which is to abstract the
entire domain into a single node. Figure 1
illustrates this idea.
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Now, we are able to maintain
two-tier price tables: domain price table for each domain and global price
table for the abstracted global network. Figure 2
give a example of global price table in our framework. In this way, we are
able to decouple the pricing for core from end-to-end pricing and enable a
fast decision making process with much less messaging overhead than using
end-to-end signaling approach such as RNAP or other type of signaling
protocols. |
We follow two simple and intuitive rules for
price setting strategy:
- The rarer the resource, the higher the
price
- Price increases rapidly or even
dramatically when the resource is scarce
Since we maintain the global price table at
access, now we can use the price for admission control immediately. In this
project, we also investigate the relationship between pricing and admission
control in details and devise an algorithm for admission control using price
as the primary criterion. |