Re: Movies, household network and 54g limits... (maybe...)
Original Message: - From: johnny [EMAIL PROTECTED] Date: Thu, 17 Jan 2008 05:06:01 -0800 (PST) To: debian-user@lists.debian.org Subject: Re: Movies, household network and 54g limits... (maybe...) I have no experience with wifi range extenders but it seems to me it should really just 'resend' the signal. If the extender is a 802.11g device, I'd expect it to produce the same throughput as the original source. I can imagine there might be some problems with both devices using the same channel. But that's just an uneducated guess. They use the same channel (otherwise how communicating each other?). I'm a bit ignorant here, only read a post of a bloke telling this... my very uneducated guess... I wrote to an author of a paper, as soon as I know something solid I'll let you know. Thanks I have a Linksys (Cisco) range extender installed. Yes it must use the same channel as the router and yes it merely repeats the signal. larry -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED] myhosting.com - Premium Microsoft® Windows® and Linux web and application hosting - http://link.myhosting.com/myhosting
Re: Movies, household network and 54g limits... (maybe...)
Well, an 802.11g network has max throughput of 54Mb/s = 6.75 MB/s It normally has an average throughput of 19Mb/s = 2.4MB/s So, either you are getting very slow MegaBITS per second or your test shows bad MegaBYTE readings :-) I can assure you that I can't get more than max 10Mbps (standard 8/9). Maybe depends upon a range extender I have in my location: I read that this kind of thing takes the global throughput to half, is it true? -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On Thu, January 17, 2008 10:30, johnny wrote: I can assure you that I can't get more than max 10Mbps (standard 8/9). Maybe depends upon a range extender I have in my location: I read that this kind of thing takes the global throughput to half, is it true? I have no experience with wifi range extenders but it seems to me it should really just 'resend' the signal. If the extender is a 802.11g device, I'd expect it to produce the same throughput as the original source. I can imagine there might be some problems with both devices using the same channel. But that's just an uneducated guess. -- Groet, Peter Teunissen --- There are 10 kinds of people in the world, those who understand binary and those who don't... -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
I have no experience with wifi range extenders but it seems to me it should really just 'resend' the signal. If the extender is a 802.11g device, I'd expect it to produce the same throughput as the original source. I can imagine there might be some problems with both devices using the same channel. But that's just an uneducated guess. They use the same channel (otherwise how communicating each other?). I'm a bit ignorant here, only read a post of a bloke telling this... my very uneducated guess... I wrote to an author of a paper, as soon as I know something solid I'll let you know. Thanks -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
johnny: I can assure you that I can't get more than max 10Mbps (standard 8/9). Maybe depends upon a range extender I have in my location: I read that this kind of thing takes the global throughput to half, is it true? Yes. There is a (more or less) fixed throughput available for both sending and receiving and since the extender has to send everything it receives and vice versa, your effective throughput is halved. J. -- I have been manipulated and permanently distorted. [Agree] [Disagree] http://www.slowlydownward.com/NODATA/data_enter2.html signature.asc Description: Digital signature
Re: Movies, household network and 54g limits... (maybe...)
On Jan 17, 2008, at 4:24 AM, Peter Teunissen wrote: I have no experience with wifi range extenders but it seems to me it should really just 'resend' the signal. If the extender is a 802.11g device, I'd expect it to produce the same throughput as the original source. When dealing with a half-duplex broadcast network like this, it's helpful to think of bandwidth in terms of time. A range extender has to take the time to listen to a packet, then it has to take the same amount of time to transmit that packet. (In a half-duplex network you can't talk and listen at the same time.) So it takes twice as much time to send a packet through a range extender as it does to send it direct. This halves the available bandwidth. Likewise, copying from a wireless device to another wireless device, through an access point, gives you half the bandwidth you'd get going from a wireless device to a wired device; the access point has to listen to each packet, then resend it. This is also why having 802.11b devices on an 802.11b/g network tends to lower throughput dramatically; the b packets take up more airtime, leaving less bandwidth available. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
Copying a 1GB file... ... **only n-devices active** ... 10MB/S average throughput Copying a 1GB file... ... **with one other g-device active** ... 7MB/S average throughput. I dunno, I copy movies server - laptop for a considerable test time and mrtg says I stay about 8/9Mbps. I would say that 1. N doesn't add so great values 2. I need more exaustive tests ;) Thanks -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On Wed, January 16, 2008 10:20, johnny wrote: Copying a 1GB file... ... **only n-devices active** ... 10MB/S average throughput Copying a 1GB file... ... **with one other g-device active** ... 7MB/S average throughput. I dunno, I copy movies server - laptop for a considerable test time and mrtg says I stay about 8/9Mbps. I would say that 1. N doesn't add so great values 2. I need more exaustive tests ;) Thanks Well, an 802.11g network has max throughput of 54Mb/s = 6.75 MB/s It normally has an average throughput of 19Mb/s = 2.4MB/s So, either you are getting very slow MegaBITS per second or your test shows bad MegaBYTE readings :-) -- Groet, Peter Teunissen --- There are 10 kinds of people in the world, those who understand binary and those who don't... -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
Because... I did some more testing... - Ok, thanks Peter for your observations. I gotta do other tests too (I'm gonna think about yours). - yeah, your architecture doesn't add but is pro ;) - Only one doubt: in a wireless network, if the router and the nics are N except one G card, I'd expect the last one drag all back (my usual idea about CSMA/CD signal-caching collisions: MAC level saturation), am I right? - I will try to write to the authors of my papers. Thanks. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On 14-jan-2008, at 10:33, johnny wrote: - Only one doubt: in a wireless network, if the router and the nics are N except one G card, I'd expect the last one drag all back (my usual idea about CSMA/CD signal-caching collisions: MAC level saturation), am I right? That's right. I'm by no means a network expert, but every wireless bridge/router manual will tell you that they are backwards compatible, but at the price of speed. When one of the 802.11g devices is active on my network, speed goes down somewhat. Little test: Copying a 1GB file from lan server to laptop en back over 802.11n b/g compatibility mode, 2.4ghz., **only n-devices active** and using netatalk I get allmost 10MB/S average throughput Copying a 1GB file from lan server to laptop en back over 802.11n in b/g compatibility mode, 2.4ghz., **with one other g-device active** and using netatalk I get about 7MB/S average throughput. That's less than pure n, but still much better than a g-only network. So the network doesn't completely switch to g-mode. If it has to do with MAC level saturation I really don't know. Peter -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
In particular, the hidden transmitter problem really bites 802.11b/g. If computer A , Computer B, and access point P... 1. Ok, but do you know papers or scientist engineers talking about a possible solution (b/g) and indicating a way (eg. drivers change)? 2. Does the story change as to n technology? If so, why? 3. If what we are saying is correct, Peter's thesis about his file server is incorrect... Sorry if I am pedant but this is the classic case in which all the playing factors gotta be hold distinct, otherwise... -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On 11-jan-2008, at 22:57, johnny wrote: For example, Peter, with N, you say is better, but may I ask you the architecture of your network? (fast: only you or...) Because of your question and the level of the discussion, I did some more testing. My original remark was just based on small observations after installing a new LAN server. You can forget my remarks about fileserving. It turned out in my case to be the combination of netatalk and routing that caused the difference. On a side note, I discovered a difference between players. When looking at the traffic graphs of Quicktime Player and VLC on Mac OSX (I'm not a pure debianite :-) I found that quicktime reads it's data at a steady rate but VLC in small bursts. That may be the reason I'm seeing a lot more interrupts when using VLC and be the cause of differences between other players too. My architecture is like pictured below. But I don't think it'll add much. Johnny, if you like me to do some testing with 802.11n, just let me know and I'll see what I can do. | DSL Bridge | |LAN Server ||| |Debian Etch | | |File / mp3 |-LAN-|WAN || | __ | ___ --|Switch|--LAN--| Router/Firewall |-- DMZ--|Switch| | DMZ Server | ___ | |__| | _| |__|--| Debian Etch | |Desktop | | | | Web / mail | ||-LAN-| __| |_| | 802.11n | |Wlan Bridge| ___ |__.| |Laptop | . |802.11n|..WLAN.. |___| . . __ _ . |Roku Player| . |802.11g|..WLAN.. |___| . . ___. |Laptop | . |802.11g|..WLAN.. |___| Groet, Peter Teunissen -- Never argue with idiots; they'll drag you down to their own level and beat you on experience. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On 11-jan-2008, at 19:03, johnny wrote: Hi, in my flat there are 1 router, 1 range extender, 2 vista, 1 XP and my 2 linux ubuntu (one of which is mail/samba/nfs/etc server, is monitored via mrtg and contains a lot of music/movies). All, wireless. The problem: when I listen to music or watch movies from my laptop (my flatmates idem) the results are not so good... many freezes... The graphs say it is clearly not bandwith fault. Reading around: It is well known that the medium access control (MAC) layer is the main bottleneck for the IEEE 802.11 wireless LANs. There are scientific publications around but seems the problem is not solved. 1. Do you know something, please? 2. With the new N technology, the problem is solved? [I doubt but I should test...] I use 802.11n (Apple Airport Extreme) and get good uninterrupted 10 MB/s thoughput. Still, when watching a movie I get a few interrupts. However, that seems to be related to the fileserver and not so much the wireless. I recently switched from an old 4x80MB raid5 set to a single 320MB disk (both with netatalk) and noticed a great improvement from to much interrupts to endure to allmost none. Still I generally copy the file over before playing. FWIW, Peter -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On Jan 11, 2008, at 10:03 AM, johnny wrote: Hi, in my flat there are 1 router, 1 range extender, 2 vista, 1 XP and my 2 linux ubuntu (one of which is mail/samba/nfs/etc server, is monitored via mrtg and contains a lot of music/movies). All, wireless. The problem: when I listen to music or watch movies from my laptop (my flatmates idem) the results are not so good... many freezes... It's actually pretty hard to get the full bandwidth that 802.11g promises. In particular, there can't be any other networks on the same channel, or on overlapping channels. (802.11 signals are three channels wide, so networks on adjacent channels affect yours.) A scanning tool such as Kismet can be helpful in picking a clear channel. If you have lots of close neighbors it may be impossible to find one. In that case using 802.11a, which runs on a different frequency band, may be an option. (Assuming the 5 GHz band is legal to use in your country.) You can't have any 802.11b devices on the network if you want to get full speed. They greatly slow things down just by virtue of the 802.11b packets taking longer to transmit, thus tying up the network for longer. Other devices that use the 2.4 GHz band can also cause problems for 802.11g. These include microwave ovens and some wireless phones. Again, switching to 802.11a may be an option if this turns out to be your problem. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
It's actually pretty hard to get the full bandwidth that 802.11g promises. Sorry if I cut a bit but your objection is fondamentally this way (possible factors: close wireless networks, 2.4GHz devices, ..., ok, but all linked to your mother reasoning). But I am telling you that if you see mrtg graphs you clearly see that G is not the problem because the bit rate of a movie is Max 2Mbps (when I use my LAN for copying with scp, I can touch 8/9 for a long time without problems). So, maybe, is something different... There is an interesting paper, Saturation throughput analysis of error-prone 802.11 wireless networks that explains just like the nature of a wireless lan (many efforts on CMDA...) take you to have more problems when there are more clients... - at least, this is the idea that I put in my mind :) - and in fact (but I have to replicate my tries) to me it would seem that freezes are worse when all my flatmates are using their laptop... For example, Peter, with N, you say is better, but may I ask you the architecture of your network? (fast: only you or...) Thank you so much, I would like to solve this problem with my cheapy devices ;) All your opinions are very appreciated, I am in England Gionni -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: Movies, household network and 54g limits... (maybe...)
On Fri, Jan 11, 2008 at 10:03:41AM -0800, johnny wrote: The graphs say it is clearly not bandwith fault. Reading around: It is well known that the medium access control (MAC) layer is the main bottleneck for the IEEE 802.11 wireless LANs. In particular, the hidden transmitter problem really bites 802.11b/g. If computer A , Computer B, and access point P can see each other, things work better. If A and B can see P, but not each other, problems arise. A starts transmitting. B doesn't see A, and also starts transmitting. P gets junk because there are overlapping transmissions. Neither A nor B see the collision, and have to wait for a timeout before retrying. This is a large window, because B could start transmitting any time during A's packet. This is also a problem when A can see B, and they start transmitting at the same time, but these occurrences are less frequent since the window is much smaller. -- Rob signature.asc Description: Digital signature
Re: Movies, household network and 54g limits... (maybe...)
On 01/11/08 17:28, Rob Sims wrote: On Fri, Jan 11, 2008 at 10:03:41AM -0800, johnny wrote: The graphs say it is clearly not bandwith fault. Reading around: It is well known that the medium access control (MAC) layer is the main bottleneck for the IEEE 802.11 wireless LANs. In particular, the hidden transmitter problem really bites 802.11b/g. If computer A , Computer B, and access point P can see each other, things work better. If A and B can see P, but not each other, problems arise. A starts transmitting. B doesn't see A, and also starts transmitting. P gets junk because there are overlapping transmissions. Neither A nor B see the collision, and have to wait for a timeout before retrying. This is a large window, because B could start transmitting any time during A's packet. This is also a problem when A can see B, and they start transmitting at the same time, but these occurrences are less frequent since the window is much smaller. Yet Another Reason why wires are better than wireless. -- Ron Johnson, Jr. Jefferson LA USA I'm not a vegetarian because I love animals, I'm a vegetarian because I hate vegetables! unknown -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
