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I was recently reading about Cluster Computing and how it used Ethernet as preferred interface. My question is why not use WiFi? It has a 300Mbps (802.11n) throughput and without all the wiring hassles and stuff? I know Ethernet has 1 - 10 Gbps throughput but to keep it under budget, like in a wired connection you'd need:

  • Cat 6 wires ( which are expensive ) - RS 12,000/10m (~120 USD)
  • 1 - 10 Gbps supported NICs - RS 3,500/Card (~35 USD)
  • Gigabit Switches (16 Port) - RS 13,000 (~130 USD)

Where as in a WiFi 802.11n you'd need:

  • just one 802.11n Router - RS 2000 (~ 20USD)
  • WiFi Link USBs (If needed) - RS 600/USB (~ 6USD )

As you can see setting up WiFi based net work is way cheaper, then why is WIFI not considered for Clustering, what are its lacking in this scenario?

PS: I'm talking with respect to my Country (Pakistan) Cat 6 wires are way too expensive and 1 -10 Gbps NICs are much more expensive

Regards

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  • 2
    Quite simple: WiFi does not reliably provide bandwidth at the scale a typical cluster needs.
    – HBruijn
    Feb 17, 2015 at 7:53
  • Nic's? Do your motherboards not come with a NIC on board? Or two ;) And for 1gigabit - CAT 5 is good enough.
    – TomTom
    Feb 17, 2015 at 8:12
  • @TomTom Yes I know but just in practice I might use PCs older then current Core series, so it might not contain 1 Gbps NIC.
    – echo_salik
    Feb 17, 2015 at 8:34
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    @echo_salik Ancient? With all respect, all computers I bought in the last 15 years had a NIC on board. And anything older than that is not worth the effort.
    – TomTom
    Feb 17, 2015 at 8:45
  • @TomTom Older PCs had 100Mbps Net connection not 1GBps. As my question states the question is b/w 1Gbps net and WiFi 300Mbps. Yes they do have NICs but not the one I am asking about.
    – echo_salik
    Feb 17, 2015 at 13:18

1 Answer 1

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  1. WiFi gives you 300 MBps only in theory. In practice it will give you way lesser bandwidth. And the more far the receiver will be from the transmitter - the lesser the bandwidth will be.
  2. $20 802.11n router is a piece of crap by design. Decent routers start from $200.
  3. $6 client adapter ... do you still believe in miracles ?
  4. You just painted out the perfect disaster plan with Gigabit switches $130 a piece. All they can do is light the gigabit link and transfer some packets.

Plus, WiFi is way more complicated than cable networks. You have to keep in mind:

  • Signal reflection and dispersion
  • Fresnel zones and other overcomplicated stuff.
  • Non-radiotransparent obstacles
  • Signal interference with multiple transievers, their power levels and mutual noize
  • External noize from microwave ovens, radiotelephones and who-knows-what-stuff-can-you-encounter on 2.4 GHz.

These things should be considered when building wifi networks. And reading this message actually doesn't give you any knowledge about how to do this, neither the understading of these things. I just named them.

As a conclusion, I should say that if the things would be as easy as you imagine them, cable ethernet would be dead for years at this point. But it's still kicking.

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    And above all, with wired switched networks, each link has all that bandwidth available. With wireless, all links share the bandwidth.
    – MadHatter
    Feb 17, 2015 at 7:53
  • For the $6 Client adapter. I am using it and believe me its a miracle that it works the way it does. Plus I didn't know that WiFi bandwidth is shared, thanks for that info @MadHatter. As for the interference, 5GHz band? 802.11ac? will that work in this scenario?
    – echo_salik
    Feb 17, 2015 at 8:29
  • @drookie: I didn't understand the Gigabit switch thing. Won't I need a Gigabit switch for Gigabit connections? Normal switches won't blow up? (figure of speech)
    – echo_salik
    Feb 17, 2015 at 8:31
  • Can anyone direct me to learn more about WiFi for reference? I would like to know more.
    – echo_salik
    Feb 17, 2015 at 8:35
  • You would need the gigabit switch for wired connections. But you probably will need it for wireless connections too - when wireless meets wired, there's always a switch. What I meant in my original post - is that there's lowest cutting price for any equipment category - and $120 for 16 ports gigabit switch is way beyond this level. It just wouldn't work. It may work for home setups (although sooner or later you will find such work really disappointing, I'm sure about that), but not for cluster.
    – drookie
    Feb 17, 2015 at 8:35

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