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Networks Will sharing using a router reduce download speed?

Discussion in 'Hardware' started by psYCHopath, 23 Apr 2003.

  1. psYCHopath

    psYCHopath What's a Dremel?

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    Hi,

    I have a ADSL connection (Download 384Kbps and upload128Kbps)


    I have a D-Link DSL500G router and a Lantec 8port switch, connected to 3 pc.
    I’m just curious that will my download speed (or is it called bandwidth) be divided in to 3 means

    384/3=128 ?????


    If 3 pc are downloading a file from a server (eg linux shrike) or from p2p software and assume that 3 of the source (server) has a constant same speed.

    Pc 1 = 128 Kbps
    Pc 2 = 128 Kbps
    Pc 3 = 128 Kbps

    Will it be like this ? (top)


    Pc 1 = 384 Kbps
    Pc 2 = 384 Kbps
    Pc 3 = 384 Kbps

    Or like this? (top)

    Can someone willing to explain this to me
     
    Last edited: 23 Apr 2003
  2. Shadowspawn

    Shadowspawn Another hated American.

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    The magic of the switch is that it doesnt split up the bandwidth. Each of your systems has the full bandwidth while talking, in theory anyway, so each system has access to the full 384 while downloading.

    Think of the switch as an 8 port valve. Only one port can be open to the router at a time. When that port is done talking, it closes, and another one opens.

    Clear as mud?
     
  3. SerpentBlade

    SerpentBlade What's a Dremel?

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    While that works in theory, you can't go over your DSL bandwidth cap, if all 3 are equally using the internet, it will be distributed equally, so its 384 split by whatever is requesting the bandwidth.
     
  4. Drastik

    Drastik What's a Dremel?

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    adding on to that question what happens with a hub????
     
  5. NuTech

    NuTech Minimodder

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    IIRC, a Hub acts similar to a switch but instead of the 'valves' opening and closing their connection to the router, they all stay open at the same time. This of course creates a lot of data collisions, meaning data has to be resent by the client PC. This, as you can imagine, wastes bandwidth.
     
  6. jake

    jake Network Gawd

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    Hubs make things a little more messy. Because a Hub is shared media collisions come into play. On any given ethernet segment only a single device can be talking at any one time. Everything else monitors the segment and shouldn't talk whilst they see another device sending information. If they should attempt to send information at the same time as another device [somethnig which happens due to propagation delays] then a collision occurs and both stations stop talking and wait for a period of time as defined by an algorithm in the ethernet standards. The algorithm includes a random component to prevent the devices from picking the same tme to start up again.

    Generally speaking you can expect get around 70% of the bandwidth availible from a busy ethernet segment before collisions become a serious problem and degrade performance. Obviously having fewer devices on the segment will effect this as will the traffic profiles of the devices in question.

    That said, the end result is still the same as with a switch, assuming the router implements no queuing or QoS policies then the PCs will all get an equal share of the availible bandwidth. Also given that generally speaking most people don't have 10Mb+ of downstream bandwidth the collisions are unliekly to be a problem unless the hub is already very busy with local traffic.

    J
     
  7. psYCHopath

    psYCHopath What's a Dremel?

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    WOW thanks everyone !!! for the great network info.... :dremel:

    now i understand......luckly i didnt get a hub... :eeek:
     
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