A derivation of Erlang's original work, the Extended Erlang B Traffic Model is an analytical model for calculating call blocking. It makes the following assumptions:
• | Calls are presented randomly to a trunk group (Poisson arrivals). |
• | Call times are fixed or are exponentially distributed. |
Unlike the Erlang B Traffic Model, the Extended Erlang B Traffic Model takes into account the extra traffic offered to a trunk group caused by retries; that is, calls that are immediately redialled because they were blocked.
This traffic model may be applied to situations in which no overflow facilities exist.
See also