# Performability of an Algorithm for Connection
Admission
Control

## J. F. Meyer

## Abstract

Connection admission control (CAC) in
broadband,
ATM-based telecommunication networks is a problem of recognized
importance.
We consider an algorithm for this purpose that accommodates variable
bit
rate (VBR) connections and is based on effective bandwidth
computations.
Arriving VBR traffic streams are assumed to be leaky-bucket regulated
and
are represented by worst-case, periodic, on-off, fluid sources that are
randomly phased. Moreover, certain traffic classes may benefit from
statistical
multiplexing (S-VBR) while others may not (NS-VBR). We then evaluate
the
ability of such a CAC algorithm to perform in the presence of
fluctuating
channel capacity, where the performability variable *Y*_{T}_{
}is the fraction of some specified busy period *T* during
which
the quality of service requirement is violated. A general base model
that
supports
*Y*_{T } is then formulated and instances of
the resulting performability model are constructed and solved using
UltraSAN.
In particular, the evaluation experiments reveal some interesting
differences
in how QoS degrades with respect to the control of S-VBR vs. NS-VBR
traffic.
**Keywords:** Broadband telecommunication networks, connection
admission
control (CAC), effective bandwidth, performability, variable bit rate
(VBR)
traffic.

**Compressed PDF File:** tc01.pdf.zip