[LARTC] external and internal LANs

[LARTC] external and internal LANs

[rani79]

hi all
what does it mean if the total network speed on internal LAN is greater 
than the external LAN 
and why it happens?
the extrnal LAN here is the Intenet using a dedicated bandwidth. and 
BTW the linux box NATting
has no shapping at all. just direct piping

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Re: [LARTC] external and internal LANs

[Jody Shumaker]

What basically happens is that the slowest link ends up controlling the 
shaping.  Usually this is the device connecting you to your ISP, and it 
tends to have a very simple buffering of data, FIFO, first in first 
out.  What this ends up meaning is that when you send data to it at the 
much faster rate of your local network, eventually you fill the buffer, 
at that point it just starts dropping packets. It's actually much more 
complicated than this, but all you need to know is that he buffer before 
the slowest link can only hold so many,  and how it sends out what its 
holding is the important thing.  With a simple fifo queue you may have a 
bunch of data from an ftp transfer sitting in the queue, then you add a 
http request to the end of the queue.  The http request has to wait till 
all that ftp data gets sent, even though it's a really tiny bit of data.

If you instead shape the data on the linux router, you can make yourself 
the slowest link.  By doing so you prevent the simple queue from filling 
up much, and can implement some sort of priorities for traffic.  If you 
gave http request more priority than ftp data, then even if your queue 
is full of ftp data, when the http request comes along it will get sent 
as soon as possible instead of waiting for all the ftp packets already 
on the queue to be sent out.

Giving TCP Ack packets higher priority is another common practice. Even 
when you're just downloading data, from say a website or ftp, ackowledge 
packets are sent to ackowledge you got each piece of data.  The other 
end will only send so much data before it waits to receive ack packets.  
Giving these rather small packets priority, your downloads will never 
suffer because of your uploads.



rani79@idm.net.lb wrote:

>hi all
>what does it mean if the total network speed on internal LAN is greater 
>than the external LAN 
>and why it happens?
>the extrnal LAN here is the Intenet using a dedicated bandwidth. and 
>BTW the linux box NATting
>has no shapping at all. just direct piping
>
>_______________________________________________
>LARTC mailing list
>LARTC@mailman.ds9a.nl
>http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
>
>  
>

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Re: [LARTC] external and internal LANs

[rani79]

i donno u seem right but i am not yet convinced.
what i have here actually is that before i install the linux router there was 
a windows server with  its caching server ISA. when i retun the windows 
server (ISA) back the speed returns to very high  dedicated speed i 
bought from my ISP. what have really is 51 kbyte/sec. but i use linux i get 
only 16 kbyte/sec.

the connection is as follows:
1- wireless connection from satallite thru penta card for down link only
2- then the ISA after the penta. which is a NAT server for 4 networks.
3- a cisco router for the UP link

so rather i take 51, i take 16  and what i have done is just replacing a 
mechine and pass the internet thru my linux, which has squid as 
trasnparent cache,  WITHOUT ANY USE OF `tc` COMMAND OR ANY 
KIND OF SHAPING!!!
THANKS. 
----- Original Message -----
From: Jody Shumaker <jody.shumaker@gmail.com>
Date: Thursday, May 26, 2005 2:55 am
Subject: Re: [LARTC] external and internal LANs

> What basically happens is that the slowest link ends up 
> controlling the 
> shaping.  Usually this is the device connecting you to your ISP, 
> and it 
> tends to have a very simple buffering of data, FIFO, first in 
> first 
> out.  What this ends up meaning is that when you send data to it 
> at the 
> much faster rate of your local network, eventually you fill the 
> buffer, 
> at that point it just starts dropping packets. It's actually much 
> more 
> complicated than this, but all you need to know is that he buffer 
> before 
> the slowest link can only hold so many,  and how it sends out what 
> its 
> holding is the important thing.  With a simple fifo queue you may 
> have a 
> bunch of data from an ftp transfer sitting in the queue, then you 
> add a 
> http request to the end of the queue.  The http request has to 
> wait till 
> all that ftp data gets sent, even though it's a really tiny bit of 
> data.
> If you instead shape the data on the linux router, you can make 
> yourself 
> the slowest link.  By doing so you prevent the simple queue from 
> filling 
> up much, and can implement some sort of priorities for traffic.  
> If you 
> gave http request more priority than ftp data, then even if your 
> queue 
> is full of ftp data, when the http request comes along it will get 
> sent 
> as soon as possible instead of waiting for all the ftp packets 
> already 
> on the queue to be sent out.
> 
> Giving TCP Ack packets higher priority is another common practice. 
> Even 
> when you're just downloading data, from say a website or ftp, 
> ackowledge 
> packets are sent to ackowledge you got each piece of data.  The 
> other 
> end will only send so much data before it waits to receive ack 
> packets.  
> Giving these rather small packets priority, your downloads will 
> never 
> suffer because of your uploads.
> 
> 
> 
> rani79@idm.net.lb wrote:
> 
> >hi all
> >what does it mean if the total network speed on internal LAN is 
> greater 
> >than the external LAN 
> >and why it happens?
> >the extrnal LAN here is the Intenet using a dedicated bandwidth. 
> and 
> >BTW the linux box NATting
> >has no shapping at all. just direct piping
> >
> >_______________________________________________
> >LARTC mailing list
> >LARTC@mailman.ds9a.nl
> >http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
> >
> >  
> >
> 
> _______________________________________________
> LARTC mailing list
> LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
> 

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