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can be assured, that the underlying IP network can provide the assumed Quality of
Service for the specific network services. On top of this technology, admission control and
resource management mechanisms are built Dynamic adaptation of resource allocation to
user requests enables the overall architecture to scaleto very large networks.
Resource Control Layer(RCL)
The RCL is responsible for the management of QoS resources inside the
AQUILA network. This can be split in three main tasks and modules:
_ End-user Application Toolkit (EAT): A graphical user
interface is offered to the
end-user directlyi or to the applications run by the user. Using this, any application can
request certain resources from the network to run
with a specified QoS. It is the
interface to the AQUILA QoS infrastructure.
_ Admission Control Agent (ACA) Performs policy and
admission control at the
network edges. Each edge router or border router is controlled by an ACA. Each ACA gets a
certain amount of resources by the RCA enabling the
ACA to perform admission control
autonomously. The
ACAs receive requests for new IP flows with specific
QoS
requirements. Their task is to authorise the requests and to check, if the network is able to
support the new
flow. For this task, they closely interact with the second
main entity, the
so-called Resource Control Agents.
_ Resource Control Agent (RCA) Monitors and controls the available resources in the
network. It is the ultimate
authority for the resource handling in the AQUILA net-work.
Based on the prior history of resource usage and
actual requests, the RCAs distribute
resource shares to the Admission Control Agents.
End-users access the Resource Control Layer by using the End-user Application
Toolkit. The EAT does not constitute a new signalling protocol forIP networks. Instead,
it can be described as a QoS middleware that brings the functionality of the Resource
Control Agents Network into the end-user terminals and servers. The internal signalling
protocol used between user terminals and the main network can be based on existing
schemes (e.g. RSVP) or even on CORBA or
DCOM interfaces depending on
application needs. In any case, the Edge Device (ED) analyses the user request and
executes the user policy control and the local admission control
operations in order to
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