Erlang's Lost Call Assumptions
To calculate the Grade of Service of a specified group of circuits or routes, Agner Krarup Erlang used a set of assumptions that relied on the network losing calls when all circuits in a group were busy. These assumptions are:
- All traffic through the network is pure-chance traffic, i.e. all call arrivals and terminations are independent random events
- There is statistical equilibrium, i.e., the average number of calls does not change
- Full availability of the network, i.e., every outlet from a switch is accessible from every inlet
- Any call that encounters congestion is immediately lost.
From these assumptions Erlang developed the Erlang-B formula which describes the probability of congestion in a circuit group. The probability of congestion gives the Grade of Service experienced.
Read more about this topic: Grade Of Service
Famous quotes containing the words lost, call and/or assumptions:
“Not for me the glad tidings of forthcoming salvation; everything is lost and I so want to live.”
—Ester Wajcblum (1924–1945)
“And when we can with Meeter safe,
We’ll call him so, if not plain Ralph,
For Rhime the Rudder is of Verses,
With which like Ships they steer their courses.”
—Samuel Butler (1612–1680)
“Assumptions of male superiority are as widespread and deep rooted and every bit as crippling to the woman as the assumptions of white supremacy are to the Negro.... this is no more a man’s world than it is a white world.”
—Student Non-Violent Coordinating Committee, African American civil rights organization. SNCC Position Paper (Women in the Movement)