Contention Ratio Formula

Posted on 2007-07-25
Last Modified: 2013-12-14
Dear Experts,

We have a student wireless hotspot network. It has 4 x 2Mb uncontended ADSL lines into a load balanced Cisco 2811 ADSL router. How do I work out our contention ratio with 300 users. We would like to offer each user a 2Mb connection.

Question by:espoke
    LVL 9

    Accepted Solution


    If all 300 users are simultaneously accessing the internet you could say that each user is getting 27.3Kb
    8MB/300 x 1024 = 27.3Kb.

    Although it doesnt quite work that way. Not everyone will be accessnig at exactly the same time and each "session" will try to grab as much of the bandwidth as it can.

    Basically you have 1 8MB connection with 300 users, so your contention ratio is 300:1

    If you want 300 users to have 2MB reserved exclusively then you'll need 300 x 2MB connections !.
    If your trying to work out the average bandwidth each user is getting then select a handfull of pc's and run at various times of the day for a week or so and calculate it out.

    IMHO anyway....
    LVL 9

    Expert Comment

    Was this of any help to you Espoke ??
    LVL 1

    Expert Comment

    Forced accept.

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