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:
“A sure proportion of rogue and dunce finds its way into every school and requires a cruel share of time, and the gentle teacher, who wished to be a Providence to youth, is grown a martinet, sore with suspicions; knows as much vice as the judge of a police court, and his love of learning is lost in the routine of grammars and books of elements.”
—Ralph Waldo Emerson (1803–1882)
“People who love only once in their lives are ... shallow people. What they call their loyalty, and their fidelity, I call either the lethargy of custom or their lack of imagination. Faithfulness is to the emotional life what consistency is to the life of the intellect—simply a confession of failures.”
—Oscar Wilde (1854–1900)
“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)