Managing Connection-level QoS through an Overlay Service Manager
P. Moghe
Network and Service Management Research Department
Bell Laboratories
101 Crawfords Corner Rd., Holmdel, NJ 07733 USA
Email: pmoghe_AT_bell-labs.com
I. Rubin
Department of Electrical Engineering
University of California at Los Angeles (UCLA)
Los Angeles, CA 90095 USA
Email: rubin_AT_ee.ucla.edu
Abstract
We illustrate the role of service management in managing the
quality-of-service (QOS) of applications. An increasing diversity
of applications is expected to be offered over ATM. Even if these
applications use the same ``media'', their connection-level QOS measures
are different depending on their connection-level resource requirements
and on their implementation at the connection layer. To illustrate
this, we consider two representative service classes. Simple applications
refer to applications that involve fixed number of
clients and point-to-point connections. Complex applications on the
other hand have dynamic client-membership and require multipoint connections.
These two service classes perceive different connection-level QOS
measures. For instance, simple applications can get blocked - external
blocking is a possible QOS measure. Complex applications can, in addition
to external blocking, suffer from internal loss. The latter is defined as
the probability that a client in an ongoing application aborts the
application because a newer client cannot add to the application.
Internal loss is a measure of how clients in a service (such as a
conference) are bound to each other at the application layer. Thus, the
QOS of complex applications is then expressed as a tuple of external
blocking and internal loss probabilities.
In this paper, we consider an end-to-end ATM platform and assume that the
traditional ATM admission problem has been solved. The service manager
resident
within each ATM switch manages QOS by an ATM overlay - that is,
it supplements the traditional ATM connection admission procedures. Its
objective, from a fairness viewpoint, is to isolate the QOS of each
service class from its implementation. We study a simple,
threshold-based scheme where the service manager gives priority when
admitting new complex applications. We compute exactly, through queueing
analysis, the QOS measures of the two service classes as a function of
the threshold. We propose an optimality criterion for the threshold
whereby both service classes suffer equal degradation. An iterative
algorithm uses this criterion to approximately design such thresholds
in the entire network.
Keywords: service management; application QoS management; resource allocation; high-level QoS management; multipoint services; conferencing applications; collaborative applications; dynamic client-membership
JNSM: Vol. 4, No. 4, 1996
Managing Connection-level QoS through an Overlay Service Manager [Vol. 4, No. 4, 1996]
NOTE: only abstract of paper available on-line
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