Autosensing in Dual Speed hubs? - Routers

This is a discussion on Autosensing in Dual Speed hubs? - Routers ; Hi, Do Dual speed hubs sense for the speed of the connected links just once when the link is connected or repeatedly as long as they are connected? Thanks in advance. Thanks, Senthil....

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Thread: Autosensing in Dual Speed hubs?

  1. Autosensing in Dual Speed hubs?

    Hi,
    Do Dual speed hubs sense for the speed of the connected links
    just once when the link is connected or repeatedly as long as
    they are connected?

    Thanks in advance.

    Thanks,
    Senthil.



  2. Re: Autosensing in Dual Speed hubs?

    When they are connected the link speed is determined and set.

    --
    Dave




    "C.G.Senthilkumar." wrote in message
    news:ct472s$lkl$1@skeeter.ucdavis.edu...
    | Hi,
    | Do Dual speed hubs sense for the speed of the connected links
    | just once when the link is connected or repeatedly as long as
    | they are connected?
    |
    | Thanks in advance.
    |
    | Thanks,
    | Senthil.
    |
    |



  3. Re: Autosensing in Dual Speed hubs?

    Thanks for the reply.

    I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
    One is newer (and hence more powerful) than the other.

    I used netperf[1] to transfer 4 different TCP streams of data of
    various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
    both directions one after the other. The maximum throughput I could
    get was only around 90 Mbps when the more powerful machine was the
    sender and around 70Mbps in the other direction.

    Why am I not getting near 100Mbps throughput? Is there something
    else going on in the Hub? I don't have any other network applications
    running on the either of the computers.

    Thanks in advance.

    Senthil.

    Ref:
    [1] netperf - a network performance evaluation tool from HP.

  4. Re: Autosensing in Dual Speed hubs?

    That's a maximum that is rarely obtained. On a hub you are on a shared segment. Only ONE
    platform can transmit at a time and has to wait until there are no sending nodes and then it
    will send. Then it must get acknowledgement packets. This is governed by CSMA/CD - Carrier
    Sense with Multiple Access/Collision Detection. Then you have to take into account the
    protocol being used, yada, yada... Then there is the OS overhead, chip-sets, LAN cards,
    etc...

    Don't worry, be happy 70~90Mb/s is good performance.

    I see you are at a University. Take a course on Networking.

    --
    Dave




    "C.G.Senthilkumar." wrote in message
    news:ct6cgi$nnh$1@skeeter.ucdavis.edu...
    | Thanks for the reply.
    |
    | I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
    | One is newer (and hence more powerful) than the other.
    |
    | I used netperf[1] to transfer 4 different TCP streams of data of
    | various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
    | both directions one after the other. The maximum throughput I could
    | get was only around 90 Mbps when the more powerful machine was the
    | sender and around 70Mbps in the other direction.
    |
    | Why am I not getting near 100Mbps throughput? Is there something
    | else going on in the Hub? I don't have any other network applications
    | running on the either of the computers.
    |
    | Thanks in advance.
    |
    | Senthil.
    |
    | Ref:
    | [1] netperf - a network performance evaluation tool from HP.



  5. Re: Autosensing in Dual Speed hubs?

    "David H. Lipman" wrote in message
    news:sTyJd.28188$Os6.25468@trnddc08...
    > That's a maximum that is rarely obtained. On a hub you are on a shared

    segment. Only ONE
    > platform can transmit at a time and has to wait until there are no sending

    nodes and then it
    > will send. Then it must get acknowledgement packets. This is governed by

    CSMA/CD - Carrier
    > Sense with Multiple Access/Collision Detection. Then you have to take

    into account the
    > protocol being used, yada, yada... Then there is the OS overhead,

    chip-sets, LAN cards,
    > etc...
    >
    > Don't worry, be happy 70~90Mb/s is good performance.
    >
    > I see you are at a University. Take a course on Networking.
    >
    > --
    > Dave
    >
    >
    >
    >
    > "C.G.Senthilkumar." wrote in message
    > news:ct6cgi$nnh$1@skeeter.ucdavis.edu...
    > | Thanks for the reply.
    > |
    > | I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
    > | One is newer (and hence more powerful) than the other.
    > |
    > | I used netperf[1] to transfer 4 different TCP streams of data of
    > | various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
    > | both directions one after the other. The maximum throughput I could
    > | get was only around 90 Mbps when the more powerful machine was the
    > | sender and around 70Mbps in the other direction.
    > |
    > | Why am I not getting near 100Mbps throughput? Is there something
    > | else going on in the Hub? I don't have any other network applications
    > | running on the either of the computers.
    > |
    > | Thanks in advance.
    > |
    > | Senthil.
    > |
    > | Ref:
    > | [1] netperf - a network performance evaluation tool from HP.


    If you want to see anything close to line speed, the first step would be to
    eliminate the hub and install a small, inexpensive switch.



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