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My Dell D630 is running a Broadcom BCM4312 802.11b/g LP-PNY wifi card using the Manjaro firmware drivers. It works but at times when I check "Connection Information" I'll see it ...
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  1. #1
    Linux Engineer TNFrank's Avatar
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    Is it normal for a wifi card to throttle back?


    My Dell D630 is running a Broadcom BCM4312 802.11b/g LP-PNY wifi card using the Manjaro firmware drivers. It works but at times when I check "Connection Information" I'll see it listed at "48Mb/s" , other times, like now when I just checked it'll be at "54Mb/s" and still at other times I've seen it at "36Mb/s" so is that normal for it to throttle back it's speed when not in use? I've never noticed this on any of my Intel wifi cards, they normally would hold a steady 54Mb/s no matter what. Also, if it's not the wifi card could it be Laptop Mode Tools doing something to throttle things back? I've disabled all the Auto Module stuff in LMT but I didn't look around to see if there was anything else that might effect wifi.
    Anyway, thanks for any answers or help ya'll can give.

    P.S.
    I went into my wifi settings and MTU was set to Automatic, I set it to 1500(really the max. rate for MTU) and saved it and now it looks like it's holding steady at 54Mb/s so we'll see if that had anything to do with it or not.

    P.S.S.
    Well, I guess that didn't have anything to do with it because it's back down to 36Mb/s when I wasn't on the interweb. I'm starting to think that Laptop Mode Tools has something to do with this.
    Last edited by TNFrank; 2 Weeks Ago at 08:32 PM.
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  2. #2
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    The internet works, in part, because of protocols that respond to network congestion. While you might think that a large MTU means better speed, if a large frame passes through a slow interface then the overall speed might be slower then a smaller packet because it must be fragmented. MTU discovery is supposed to deal with that issue.

    It's possible that what your interface is reflecting is the state of the network at that given time. In any case the numbers don't mean that much in terms of real speed - you are rate limited by the network you are transversing as much as by your card.

  3. #3
    Linux Engineer TNFrank's Avatar
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    I know that an MTU of 1500 is really just the Max. that you can have and that most times it'll be much slower. Gamers set their MTU to 1500 to get as much through put as they can while gaming and if you want to throttle someone back you can set them to a lower MTU, I get all of that, I just wondered if with it set to Automatic it was adjusting my wifi card back when it was not needed or something but I guess that's not the case since setting it to the max of 1500 really did nothing. The Connection Information is still back and forth with Mb/s speeds and it seems that it depends on what I"m doing.
    My DSL is only 6Mbps(5.6Mbps acrually although I'm paying for a 6Mbps connection, go figure that one out, LOL) so even when the connection info is 36Mb/s it's still more then I've got to use.
    I've just never really seen this before(never really looked but still) and wonder if it was a normal thing or if something was up.
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  4. #4
    Linux Guru rokytnji's Avatar
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    Well, I know with my wireless N router from Windstream. If I connect with a Wreless G network card. All other wireless N computers in the house
    also drop to wireless G speeds. If a hook up a wireless B laptop, Then the same goes for the other computers also.

    Maybe you have a script kiddie on your network/wifi?
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  5. #5
    Linux Engineer TNFrank's Avatar
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    Nope, I live Rural and my daughter next door has her own wifi and my neighbors all have their own wifi and I doubt any of em' know how do hak a wifi modem. Heck, I had to set my daughter's modem up for her, LOL.
    Both of my laptops and my wife's netbook are 802.11g, not sure what the Roku is, probably 802.11g as well but even g speeds are 54Mb/s and I've only got a 6Mb/s connection so everything would run at a higher speed then my connection so it's not a matter of one thing pulling another down.
    I can have my D630 and only my D630 on and the Connection Information will show anywhere from 36Mb/s to the full 54Mb/s, no real rhyme or reason behind it as far as I can see.
    Oh well, guess I should just be glad that it works.
    "Now, what y'all wanna do?
    Wanna be hackers? Code crackers? Slackers
    Wastin' time with all the chatroom yakkers?
    9 to 5, chillin' at Hewlett Packard?"

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    Linux Guru Rubberman's Avatar
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    Frank, I also have a D630, running Scientific Linux 6.5. One thing I know as an EE with some little experience in wireless and cellular technologies is that speed depends upon a lot of factors, including (sic) the "phase of the moon"... Just kidding, but environmental factors, interference from other RF sources, etc will impact the throughput of your WiFi gear. One common one is that most WiFi gear is defaulted to channel 6 or 11 so there is a lot of contention from neighboring AP's and devices. Changing your signal channel to something else, such as 4, or 9, or something else, may help. We use channel 8 which seems to work pretty well.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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