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with only at the application level. Network lower level details which are specified in terms
of jitter, delay, throughput are dealt separately with at the network layer and it is
usually, difficult for application developers to specify their network level QoS
requierments at design or run-time. In this work, we shall restrict our attention to
enterprise networks and enterprise applications. Internet is too big a domain to start
tackling, even though the protocols may be the same.
SLA and QoS parameter at the application layer reflects the quality of service to
the customer. It should be easy for customers to understand the degree of assuring the
service. They can be different according to the types of service. On the other hand,
network QoS parameters means the basic metric of performance measurement of
network level QoS at the network management layer.
Objective in the whole process is the mapping of NPMs to QoS parameters (SLAs)
and then giving the view of the net-work in terms of SLAs to applications, pricing,
conformance etc and not in terms of NPMs to customer, network provider and application
provider.
Here, we collect NPMs from the network through SLA agent and then map
them to QoS.
Say, some application wants a delay of less than 10 sec. We should be able to
collect the Network state (which is nothing, but NPMs which are: traffic congestion,
throughput, availability and latency).
As an example for the IP enterprise network, the SLA of some service provider
with the customer can be as follows: The availability over 99.99 % should be assured. The
average RTT (round trip time) should be less than 50 msec. The delivery ratio should
be more than 98.0%.
The QoS network parameters would be in terms of availability, delay, jitter,
latency and loss. Since, the network performance metrics are gathered through network
monitoring methods, we need to convert these network statistics to QoS network
parameters at the network management layer which needs to be mapped to the SLA at the
application layer above.
The network monitoring methods use to measure network performance and QoS
parameters can be : active monitoring, passive monitoring and through SNMP agents.
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