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Drivers
Requirements
QoS
Architectures
MPLS
GMPLS
IPv6
IP-Node
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IP QoS Architectures and MPLS
  
Over the last years, the Internet has been so
successful that IP technologies are now expected to play a critical
and potentially dominant role in the evolution of both public and
private networks.
The provision and support of new distributed multimedia services are
of prime concern for telecommunications operators and equipment
suppliers. Therefore, the potential of the latest Internet protocols
to contribute communications components is of considerable interest
to all parties.
An important issue in the Internet, and consequently in every
network connected to it, is support for multimedia applications
(e.g., video, voice). These applications have specific requirements
in terms of delay and bandwidth which challenge the original design
goals of IP's best effort service model, and call for alternate
service models and traffic management schemes that can offer the
required quality of service (QoS). To this end, two QoS
architectures have emerged in the IETF: integrated services (IntServ),
which provides end-to-end QoS on a per-flow basis, and
differentiated services (DiffServ), which supports QoS for traffic
aggregates. Both proposals suggest solutions to overcome the QoS
limitations in the current best-effort IP service architecture.
In both schemes the differentiated service levels - matching
performance to user needs and pricing - promise to transform the
Internet from today’s rough one-size-fits-all vehicle into
tomorrow’s versatile answer to a variety of traffic requirements.
The other significant development is in the field of IP
routing/switching. The industry is developing new mechanisms that
improve the efficiency of packet forwarding: resolve the issues of
the scalability of routing, the provision of more flexible routing
services, increased performance, and more simplified integration of
layer 3 datagram forwarding and layer 2 switching technologies. This
all has led to the concept of MPLS with the overall goal of
providing a standard label-swapping architecture.
Here we review these two proposals and MPLS on how such QoS enabling
schemes could be utilized to enhance the best effort service model
of IP architecture. The remainder of this chapter is structured as
follows. We first briefly look at the key drivers of IP network with
QoS requirements. Then we outline a classification of applications/
services and their requirements, and identify the need to support
applications that have strict QoS requirements, the so-called
critical applications. We then review recent developments and
research results proposed to improve the Internet in order to
support real-time and multimedia communications. We analyze two
proposals enhancing the current Internet communication service
architecture (currently limited to a ‘flat’ best-effort service): we
look at the integrated services and more recent proposals for
differentiated services in the Internet. Further, Multi-protocol
Label Switching, and IPv6 (the new version of the Internet Protocol)
are analyzed. In each case, we attempt to provide critical reviews
in order to assess their suitability for this purpose. Finally, we
indicate what the basis of the future infrastructure might be in
order to support the full variety of application requirements.
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