Multicast rate setting

Has anyone done any experimentation to analytically try and determine how to best set the multicast rate on devices on a network?  I'm thinking that since the airport utility will display the signal, noise, and rate information it would be simple to graph what the average rate readings were when the only variable in the experiment was a change to the multicast rate setting.
I'm thinking that you'd arrive at some kind of idea of what to set the multicast rate setting to, based on the signal to noise ratio and throughput.
For example if the highest rate obtained between two devices with the same relative signal to noise ratio was 400 with a particular multicast rate setting on the base unit (connected to the internet) that would be the setting to use. If you experimented by changing just the multicast rate and nothing else, and the rate dropped to 300 for the same relative signal to noise ratio, then that would indicate where to set the multicast rate to.
I hope I'm making sense.
I've recently re-configured my network when I picked up a new 5th generation Airport Extreme and without doing anything my 5Ghz channel connection rate increased by 50%. That's between a 4th and 5th generation Airport Extreme. the rate went from 300 to 450 just by changing the one base station.
I know the 5th generation unit has improved antennas and higher signal output.
What's interesting is that from the 5th generation (base unit connected to the internet) to a 4th generation unit and 3rd generation unit that display identical signal and noise readings to the base unit. The 4th generation device is consistently and constantly higher in terms or xmission rate (450) while the 3rd generation device tops out at (270). The 3rd generation unit is on the same floor as the base unit and much closer than the 4th generation unit. This resulted in the equal signal and noise levels received at the base.  You would think that the closer unit  (which actually has a 1 db higher received signal at the base unit) would show an equal data rate.
So I'm wondering if Apple did more than just increase the signal level in the new units. Does anyone know what the maximum possible rate readings could be for each generation of extreme base station?
Well, hopefully this pretty technical dive into observed differences between units stimulates some conversation.  I only wish I still had access to an RF anechoic chamber and shielded rooms so I could do some real testing.

Tesserax,
I completely understand how multicast works and it's effect on throughput performance. What I was wondering was, if anyone had done any studies or testing to determine that, for example: a multicast rate setting of 10Mbps requires the received signal to be at least 20db above the noise floor and no more than 3 clients connected at the same time.
My reason for being interested in this is that I've divided my home into an upstairs / downstairs network where the upstairs network is linked to the bottom one (which contains the internet access) via a wireless bridge. (running a 'hardline' ethernet connection is not feasible for me at this point) each network has a couple of base stations tied (hardline) to computers and media centers that require high throughput rates (for internet connections and media streaming)
The upstairs/downstairs bridge and these high throughput base stations have been isolated to be on the 5GHz band only. Since there are only 4 of these devices on this isolated network, I'm experimenting with doing everything I can to maximize the throughput over the 5GHz network.  The 2.4GHz network (aren't simultaneous routers great!) is serviced by airport express units on both floors and handles all of the 'mobile' and 'lower' speed network needs such as iPads, iPhones, AirPlay (audio). The have lower multicast settings so that they can handle people carrying their iPads and iPhones around while providing great wifi coverage.
I was hoping that someone knew of someplace that a study might have been done that I could read. Maybe I'll have to do it myself over some holiday weekend and post the results.  Since playing with the mulicast rate will affect the ability of devices to connect to each other, I think it should only be used as a 'throughput controller' when you're in a situation like I have where you have a 'backbone' network between fixed points that does not have to support clients coming in and out.
Do you happen to know what the full bandwidth potential is for the 5 and 2.4 GHz bands between 2 devices?

Similar Messages

  • What should the multicast rate be set at?

    what should the multicast rate be set at in the wireless options box?
    mine was set at the default of 6 Mbps but could be set higher: 9, 12, 18 & 24Mbps.
    Any care to explain what it does?
    Regards Simon

    That sets the minimum date rate which is valid for a connection. If a connection can't maintain that rate, the connection will drop.
    A side effect of setting it higher is that your usable range will decrease. You will need to be closer to the base station to maintain a higher data rate.

  • Airport Extreme multicast rate and closed network

    New to Airport Extreme.
    Is the multicast rate the same as the TX rate on other routers? I chose 11Mbps during the setup and my Macbook was very slow. I moved it back to 2 Mbps and it sped up. Distance from macbook to airport approx. 24 inches.
    Other question/ statement. I assume that the closed network portion of the setup is the same as turning off the SSID of other routers. Do I assume correctly?

    goldengti, Welcome to the discussion area!
    Is the multicast rate the same as the TX rate on other routers?
    Sorry I don't know about other routers. The multicast rate defines the minimum data rate the base station will use and maintain the wireless connection. If you set it to 11 Mbps, the wireless connection will be broken if that data rate can't be maintained.
    Other question/ statement. I assume that the closed network portion of the setup is the same as turning off the SSID of other routers. Do I assume correctly?
    Yes the same useless option. Regardless of how you set this option on any router, the SSID is still broadcast between any connected clients and the base station. Therefore it only takes a few seconds to discover the SSID.

  • Questions about MultiCast Rate

    1. What is MultiCast Rate?
    2. The default is 2 Mbps, isn't it? Is it country dependent?
    3. How to choose among the 1, 2, 5.5, and 11 Mbps options available?
    4. Can the choice affect the interference with other devices?

    1. What is MultiCast Rate?
    The Multicast Rate option sets the threshold throughput level a wireless client must obtain in order to be "accepted" by the base station. The lower this value, theoretically, the greater number of clients that can connect, especially those at greater distances from the base station. At the opposite end, the higher this number, only those wireless clients that can achieve the higher throughput value will be able to connect.
    Every client negotiates bandwidth individually. Regardless of what the multicast rate is set to, the clients are going to be using the highest data rate their connection to the base station is capable of. Therefore the clients close to the base station will be using a high data rate while the clients far from the base station will be using a lower data rate. If the data rate to any client falls below the multicast rate, that connection will be dropped.
    2. The default is 2 Mbps, isn't it? Is it country dependent?
    That would depend on the firmware version that is running on the AirPort. For example, on the simultaneous dual-band AirPort Extreme, this option only provides for Low, Medium, or High settings. It is NOT country dependent.
    3. How to choose among the 1, 2, 5.5, and 11 Mbps options available?
    You would use the AirPort Utility to select the MultiCast Rate from the Wireless Network Options panel.
    4. Can the choice affect the interference with other devices?
    No. This setting is totally different than the radio channel setting. Having two base stations near each other, that are operating on the same channel, will cause Wi-Fi interference between them.

  • AirPort Extreme Multicast Rate limitation

    I am currently using an iMac G5 which has an AirPort Extreme card with firmware 405.1. I have an AirPort Extreme (802.11n) base station that is running firmware version 7.1.1. My Radio Mode is "802.11n (802.11b/g compatible)." My wireless security is WPA/WPA2 personal.
    When I go into my Wireless Options, my Country is United States, my Transmit power is 100% and my WPA Group Key Timeout is one day. It is not a closed network and I do not use interference robustness.
    When I open the options for "Multicast Rate," the highest available rate is 11 Mbps. From what I understand, wireless G is capable of 56 Mbps (and that is how Apple advertised the Airport Extreme card when I bought it). Why is my multicast rate limited to 11 Mbps and how can I raise it to 56 Mbps?

    I've always been a little foggy on multicast. The apple support article seems to imply that it only matters when "certain audio and video streaming servers or other applications with multicast capability" are on your network. (http://docs.info.apple.com/article.html?path=Airport/5.0/en/ap2087.html)
    What if you don't have one of these multicast servers or applications on your network? Does the multicast rate have any effect on your network performance?
    My understanding is that the answer is YES - regardless of whether you have one of these multicast servers or not, setting your multicast rate to X means that only airport clients that can achieve a speed of X or greater will be able to connect to the base station. If you set it to 1, then you will extend the range of your network. But sometimes, in a WDS, where multiple base stations on the same channel overlap, I find that my clients have trouble deciding which base station to connect to. So actually, it works better to set the rate a little higher. But I am never quite sure if this is true, or if its just my imagination.
    At any rate (no pun intended) , I'm still foggy on multicast and would really appreciate if someone out there could clear things up or direct me to a link that explains what i need to know (starting with an actual definition of multicast).
    Thanks

  • Multicast Rate?

    What is Multicast rate? I don't understand it. What should I set mine on and why?
    Kevin

    Multicast rate is the lowest rate at which the wireless connection will be maintained. If you set the rate higher the range of the network will decrease since you will need to be closer to base station to achieve that rate.
    AirPort 5.0 Help: Controlling the quality of audio and video streaming

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    Kind Regards,

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    Maybe Audition just isn't the best software option for this, but since we have CS6 Premium I had hoped I could utilize software I already had. (And for the live video casts I'm looking at starting out with Google hangouts...)
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  • Audition 3 seeing a different sample rate setting than what the device shows

    Hi,
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    Dale

    DaleChamberlain wrote: Anyone know of how I can change these settings to get Audition to agree with the device settings?
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