Question

Explain MBAC algorithm logical parts and Measurement sum,Acceptance region, Equivalent bandwidth

Answer 1

MBAC(Measurement Based Admission Control) algorithm :
   Basically, the MBAC algorithm consists of two logically distinct aspects.
1)The first logical aspect is the controlling criteria for admitting a new flow and this aspect is based on approximation of traffic flow.
2)The measurement process is the second logical aspect. There is a need for a measurement process, to use MBAC methods.
Two commonly used MBAC mechanisms are measured sum and equivalent bandwidth(effective bandwidth).
i)Measurement sum:(The measured sum approach)
Measured sum is considered to be the simplest MBAC algorithm.
We have R+C < $\Theta$ .T where C is the existing network load, T is the total link capacity and R is the resource request. Here the resource could be bandwidth. $\Theta$ is the utilization target.
This gives the admission criterion for the measured sum.

ii) Equivalent bandwidth approach : Basically an equivalent bandwidth is defined as the bandwidth C(a) in such a way that the stationary bandwidth requirement exceeds this value with probability at most a.
Note : Equivalent bandwidth will be calculated by using the Gaussian distribution.

T is the length of the measurement block used to determine maximal packet delays and this parameter T always provides us with a region of reliability. Note that increasing T makes the admission control algorithm more conservative.
Generally, we will choose a T value for each simulation that yielded no delay over the simulation at acceptable level of utilization.