Does the phone exchange a net to have reason

From;    Author:Stand originally


If have many users when, to make sure random can communicate between two users, very natural we can think of every two users use a pair of circuitry to rise repeatedly.

Circumstance of 5 users connective:

When N=5, what use line

=4 3 2 1=10

N user connective circumstance:

What use circuit =n(n-1)/2

The line logarithm that because this is become,needs more mushroom, want, if be opposite for every user, need to receive N-1 in the home to the line, before calling, still need to mix him word machine line be callinged rises repeatedly, that is too troublesome!

Then people thought up a tweak, be in the concentrated center that the user distributings, install an equipment, this is just like is contact of a switch, open at ordinary times, when needing to communicate between two users arbitrarily, equipment join the line of two users puts through. Can see from this, equipment but the requirement of the person that the basis sends a word, finish with the task that information exchanges between another user, so this kind of equipment calls a phone switching equipment. Actual switching equipment is quite complex, but had a phone to exchange equipment, n user, need N to be able to satisfy a requirement to the line only, make the charge of circuit is reduced greatly. Although raised the cost of switching equipment, but it will be N the user serves, utilization rate is very high.

(the hair family history that this is telegraphic bureau, hoho... )


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