[K12OSN] K12OSN Digest, Vol 77, Issue 14

brian mullan bmullan.mail at gmail.com
Wed Jul 28 21:30:06 UTC 2010

You sound like you are assuming its a s/w or local LAN problem BUT don't
forget your WAN connection to the internet.

Since you are talking about watching YouTube over the internet you should
verify what your internet link speed is as well as whether you are having
any WAN-side problems.

Initially try just doing a PING to www.youtube.com.    What is your response
time ? I'd probably expect sub- 60 millisecond responses.   If you get
something much higher then delay could be a problem.

You've mentioned your LAN speeds but what is your WAN/internet link speed ?
2mbps, 10mbps, more?

You will need to find out whether your WAN link is

1) at or near capacity which would cause poor video
2) having problems with errors (video is highly susceptible to dropped
packets), if you can't check your internet router then ask someone to do so
just to make sure you are not taking hits on your WAN interface whether that
is DSL, Cable, etc.
if its a cisco router you can log in and use the SHOW INTERFACE command to
look for thinks like CRC errors, retransmissions etc.

There are a lot of free Internet Speed test sites out there where you just
click on a button and it will measure up/down speeds to the pc you are
using.   Try to use a legitimate site like maybe your Service Provider if
they have one.

Brian Mullan

On Wed, Jul 28, 2010 at 12:00 PM, <k12osn-request at redhat.com> wrote:

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> Today's Topics:
>   1. Where is the bottleneck? (Joseph Bishay)
>   2. Re: Where is the bottleneck? (Christian Einfeldt)
>   3. Re: Where is the bottleneck? (CLIFFORD ILKAY)
> ----------------------------------------------------------------------
> Message: 1
> Date: Tue, 27 Jul 2010 19:08:40 -0400
> From: Joseph Bishay <joseph.bishay at gmail.com>
> To: "Support list for open source software in schools."
>        <k12osn at redhat.com>
> Subject: [K12OSN] Where is the bottleneck?
> Message-ID:
>        <AANLkTik8_Z7oWQkJ4cqeCJnUEjYc48pnB0M_sotgNf_N at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> Hello,
> How are you doing?  I hope all is well.
> So I was recently informed by one of our staff that our LTSP
> (k12Linux) system is too slow for youtube videos.  Not being a youtube
> person (at least at work!) I had never really tried it so I gave it a
> test now.
> Setup:
> Server -> gigabit card -> gigabit switch -> gigabit client (Dell
> Inspiron 530 - Core 2 Duo processor 1 GB RAM)
> Ran the test when there was no one else logged into the network.  Gave
> the Old Spice youtube video a whirl (
> http://www.youtube.com/watch?v=owGykVbfgUE ) (ran it at 480p setting)
> and it's horrible. It's not a video as much as a fast-flickering
> slideshow.  Just to put it further I ran it at full-screen mode and it
> looked more like a powerpoint slide presentation than a video.
> I tried re-running the video several times, to see if having it in
> memory/cache made a different but it didn't.
> So I'm not sure what is the problem.  I recently purchased the gigabit
> switch specifically to help speed things up but now I'm very worried.
> What do you recommend I do in order to determine the location of the
> bottleneck?
> thank you
> Joseph
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