[vlc] Re: Wireless Multicast Stream

[Galen]

Sorry, I was replying really fast to your email right before heading 
out of town. I have the DWL-900ap+ and DI-614+. I've also played 
briefly with a few other models (DI-514, etc) which seemed to have 
similar results. I'm using them in AP mode, I don't know how they would 
work in other modes. In my experience, there can be some slightly odd 
behavior when D-Link APs are used in non-AP mode. Not always a problem, 
but sometimes unusual.

As far as the settings. Well, if it was a big stream, I turned the 
multicast rate up as high as need be (up to 11 Mbps). There are some 
settings relating to blocking multicast packets and things like that 
which I had to adjust to make it work. But pretty much, a few minutes 
configuring then multicasting worked perfectly. I only had a handful of 
clients logged onto the network, all OS X boxen via Airport/Airport 
Extreme/Belkin USB 802.11b connections.

I'm not at home and won't be for a while so I can't find the exact 
settings for you. I think if you poke around online at the D-Link site 
you can find an online emulator of the some D-Link router/AP web 
interfaces. Email me, probably off-list, next week and I can tell you 
what my settings are. Or feel free to email me if you have specific 
settings questions...

-Galen



On Nov 20, 2004, at 11:25 AM, Eftychios Eftychiou wrote:

> Thanks everyone for their suggestions and input.
>
> Galen can you please be more specific as to which D-Link hw you used 
> and what settings!
>
> I have a DWL-2100 AP that was planning to use in client mode.
>
> Thanks again
> ----- Original Message ----- From: "Galen" <galen at myhome.net>
> To: <vlc at videolan.org>
> Sent: Saturday, November 20, 2004 6:50 PM
> Subject: [vlc] Re: Wireless Multicast Stream
>
>
> I have mostly D-Link products (yeah, yeah...) and am relatively happy.
> Multicasting works perfectly. I even tested three simultaneous,
> uncompressed CD-quality audio streams without problems for roughly 12
> hours. Never seen a problem.
>
> I did, however, have to make sure my firmware was up to date and adjust
> a few settings. I wireless APs like to throttle/block/tweak
> multicasting messages by default, so it's best to fix that. And as the
> earlier poster said, the multicast rate should be adjusted according to
> your signal levels around the wireless network.
>
> That's my 2¢...
>
> -Galen
>
> On Nov 19, 2004, at 2:35 PM, Benjamin PRACHT wrote:
>
>> On Sat, Nov 20, 2004, Eftychios Eftychiou wrote :
>>> Can someone recommend a specific Wireless router that will multicast 
>>> a
>>> video stream effectively? I know the Dlink 624 will not allow any 
>>> mutlicast
>>> traffic to the wireless AP.
>>>
>>> Thanks
>>>
>>> Eftychios
>>>
>>
>> Well, I'v successfully streamed about 6Mbit/s of udp multicast traffic
>> on a Symbol Spectrum 24 AP 4131 11 Mbit/s Access Point with an
>> acceptable packet loss (I haven't tried with other hardware). However,
>> don't expect it to work out of the box (default settings give about
>> a 10 kbit/s bitrate). Indeed, the layer 2 part or the 802.11 norm
>> wasn't really designed for broadcast of high rate streams. Broadcast
>> / Multicast frames are sent using the lowest available transfer rate
>> available on the AP (1 Mbit/s by default), so that every endpoint, 
>> even
>> those who are at the limit of the range can receive them. Moreover,
>> for energy saving reasons, broadcast / multicast frames are only sent
>> every so called DTIM intervals (every 0.3-1s by default on most AP).
>> Indeed, every node of a wireless network is supposed to wake up at 
>> such
>> intervals, to receive broadcast frames. As a consequence, broadcast
>> frames have to be buffered in the AP between 2 DTIM.
>>
>> So, to make short, to improve the multicast bandwidth on an AP:
>>
>> - Increase the rate the minimum available bandwidth of your AP (at the
>>   cost of range of the AP
>> - Increase the size of the buffer allowed for broadcast / multicast
>>   frames (not all AP offer this feature, the Symbol one did)
>> - Decrease the interval between 2 DTIM (send one every beacon, for
>>   instance) at the cost of the power consumption of the nodes on the
>>   network...
>>
>> -- 
>> BigBen
>>
>> -- 
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