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Need help calculating network bandwidth

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Wang191

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Hey guys,
I need help calculating how much bandwidth is being used by 25 Slingboxes on a network. The Slingbox website says it needs 3Mbps or higher for HD streaming so I want to use that as a base point.

The second part of this is: Will this kill the network?
The Slingboxes are connected to a Cisco switch (I am not sure of the model) but each port is a Gigabit link.

I realize the Slingbox can auto-sense network traffic and adjust it's picture quality and bandwidth usage but I need a base point to start from.


Thanks in advance.


Edit-
If I do this calculation via a method I saw at one website:
If your network is GbE, that would give you 125,000,000 bps. This is computed by taking the 1000 Mbps (for a Gigabit network); which is 1 billion (1,000,000,000) bps and dividing it by 8 to come up with the bytes.
(1,000,000,000 bps / 8 = 125,000,000 Bps)
Then 125,000,000/393 216 bytes per second (for slingbox)
I get 317.8 which would be the number of Slingboxes able to be on the network.


Yet if I use this website http://web.forret.com/tools/bandwidth.asp?speed=3&unit=Mbps
Then a 3Mbps device will use almost the entire 1gig pipe.

I'm confused.
 
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There is other over head with Ethernet which makes the total available bandwidth less than your calculation. I use divide by 10 as a rough estimate for a theoretical max. But there are so many other pieces in a network that affect performance it's hard to predict what you will actually get. Is anything wireless, etcetera? Maybe someone else here can give you better real world experience than I can.
 
There's no wireless in the network or anything like that.
I actually just recalculated with 50% overhead so:
500Mbps/3Mbps = 166 concurrent sessions

Is this a correct calculation?


you're saying take 10% off the top or actually divide by 10 meaning 1Mbps available bandwidth?
 
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Wang191 said:
There's no wireless in the network or anything like that.
I actually just recalculated with 50% overhead so:
500Mbps/3Mbps = 166 concurrent sessions

Is this a correct calculation?


you're saying take 10% off the top or actually divide by 10 meaning 1Mbps available bandwidth?
Click to expand...

I guess what I'm saying is on any given port that is running gigabit speeds I divide by ten for the max throughput on that port. So your 1gbe port can do 100MBytes per second maximum. Tom's Hardware did some testing using a system that could actually push data as fast as the network and achieved 111MBps ( so divide by nine may be more accurate). Standard client to server they got about 40MBps. So I would take 40MBps*8/3Mbps=106 minus any overhead the switch introduces as the max number of Slingboxes a single port can feed.
 
Where are all of the slingboxes sending their data? Are you putting all of them on a single gbit link? Are they are all going to be on their own port, and go out 1 destination port, or are they coming in one port and going out another, or does every sling box and destination have it's own port?

Need more information
 
It's simple math. If they say each one needs 3Mbps, then 25 of them would require 75Mbps total. Like mtrupi said, there's overhead, so you're probably better off assuming that your 1000Mbps gigabit will in reality be more like 100-110MBps (rather than the full 125MBps). Figuring 90% efficiency after overhead, that would still leave you 900Mbps, which would work out to 300 units.

But if they're all going out a single 10Mbps internet pipe or to a single server, that's a completely different bottleneck to consider.

P.S. Bump because I want to know what this is for too. =)
 
The Slingbox website says it needs 3Mbps or higher for HD streaming
Click to expand...

remember you are using the suggested minimum speed for your calculations. in reality, and depending on what you are streaming, it could be higher. best thing to do would be to buy one and do some real life testing with the video that you will be streaming.

it also matters if this is going over the internet, or if its all being streamed internally on your own network, as there can be even more overhead when you send it outside your own network.

im also interested in the use of 25 slingboxes...
 
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