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Before commiting a resource reservation request, some admission
control
algorithm is used that ensures if sufficient resources are available to meet the request.
Above, method assumes DiffServ network. They have beutifully and effectively
solved the problem of mapping SLA which may be specified using QML, HQML or using
Aquila's applicationprofile DTDs and service component DTDs into SLS (technical
aspects of SLA requirements of applications) and then into 5 network services that most
closely meet its requirements.
The 5 network services as done in Aquila architecture are:
1) Premium Constant Bit rate (PCBR).
2) Premium Variable Bit rate (PVBR).
3) Premium Multimedia (PMM)
4) Premium Mission Critical (PMC)
5) Standard Best Effort (STD).
The 5 network services are provided by creating 5 traffic classes (TCL) as follows:
1) First TCL has a queue and has the highest priority.
2) Rest 3 are respectively in smaller priorities and controlled using weighted fair
schedulling.
3) Last one is of the smallest priority and is best-effort service. Yet, some resources are
reserved for it too.
4) Different network parameters such as bandwidth, peak
rate, average rate are controlled
using leaky token bucket (and sometimes, dual leaky token bucket to control average
traffic rate for a period of time, also).
The above details of traffic classes are then used to allocate resources in DiffServ network.
The end to end state is ensured by maintaining the logical resource pool in the
layer above network that keeps track of the resources. This logical layer is known as RCL
(resource control layer).
Thus, to implement above mapping schema, to MPLS networks, we would
need to map network services to the MPLS TE. Thus, bringing changes to the RCL
(resource control layer).Aquila Architecture has already been explained in detail in the
earlier section of related works.
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