[LARTC] Artificial latency

[LARTC] Artificial latency

[Ryan Agler]

I have a situation where I would like to introduce an artificial delay of
100 milliseconds to incoming UDP traffic to a particular client.  Here is my
setup:

                 +-------+          +-----------+
                 | Linux |          |           |
'Internet'---eth1| NAT   |eth0===|192.168.1.4|
                 |       |          |           |
                 +-------+          +-----------+

Note I'm not looking to restrict the RATE or SPEED at all, just to add a
DELAY, and only to incoming UDP packets coming in from the Internet destined
for 192.168.1.4.  I have kernel 2.4.20 with all the latest and greatest tc,
htb patches, etc.

Can anyone help??

Thanks much,
+Ryan


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Re: [LARTC] Artificial latency

[lartc]

hi ryan,

i had asked a similar question a while back, and stef recommended the
following:


http://snad.ncsl.nist.gov/itg/nistnet


make sure to read the faq!

cheers

charles


On Sun, 2003-06-08 at 01:19, Ryan Agler wrote:
> I have a situation where I would like to introduce an artificial delay of
> 100 milliseconds to incoming UDP traffic to a particular client.  Here is my
> setup:
> 
>                  +-------+          +-----------+
>                  | Linux |          |           |
> 'Internet'---eth1| NAT   |eth0===|192.168.1.4|
>                  |       |          |           |
>                  +-------+          +-----------+
> 
> Note I'm not looking to restrict the RATE or SPEED at all, just to add a
> DELAY, and only to incoming UDP packets coming in from the Internet destined
> for 192.168.1.4.  I have kernel 2.4.20 with all the latest and greatest tc,
> htb patches, etc.
> 
> Can anyone help??
> 
> Thanks much,
> +Ryan
> 
> 
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/






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RE: [LARTC] Artificial latency

[Ryan Agler]

Hi Charles,

Thanks for your response!  I followed your advice and installed the nistnet
kernel module, and after a lot of wrestling it worked.

Ill explain why I need a delay to incoming UDP traffic -- 192.168.1.4 is a
Cisco ATA-186 Analog Telephone Adaptor, which lets me hook up a normal
phone/fax machine and place calls over the Internet.  It turns out that
there is a slight asymmetric delay, i.e. the time between when I speak into
the phone and its heard by the person I call is longer than the time between
her speaking and me hearing it.  This is fine for voice, but intolerable to
my fax machine.  So, I used the nistnet module to delay incoming UDP packets
to 192.168.1.4 by 300 milliseconds, and got the 'symmetric' delay I was
seeking and faxes are working!

I am wondering if anyone out there can think of another delaying solution
using a qdisc??   I had many problems getting the nistnet module installed;
it refused to coexist with an lt_serial module that allows my faxmodem to
work, and causes sporadic fits with my kernel.

Any advice is appreciated!

Thanks,
+Ryan

-----Original Message-----
From: Charles Shick [mailto:chuck.shick@manchotnetworks.net] 
Sent: Sunday, June 08, 2003 4:12 AM
To: Ryan Agler
Subject: Re: [LARTC] Artificial latency

hi ryan,

i had asked a similar question a while back, and stef recommended the
following:


http://snad.ncsl.nist.gov/itg/nistnet


make sure to read the faq!

cheers

charles


On Sun, 2003-06-08 at 01:19, Ryan Agler wrote:
> I have a situation where I would like to introduce an artificial delay of
> 100 milliseconds to incoming UDP traffic to a particular client.  Here is
my
> setup:
> 
>                  +-------+          +-----------+
>                  | Linux |          |           |
> 'Internet'---eth1| NAT   |eth0===|192.168.1.4|
>                  |       |          |           |
>                  +-------+          +-----------+
> 
> Note I'm not looking to restrict the RATE or SPEED at all, just to add a
> DELAY, and only to incoming UDP packets coming in from the Internet
destined
> for 192.168.1.4.  I have kernel 2.4.20 with all the latest and greatest
tc,
> htb patches, etc.
> 
> Can anyone help??
> 
> Thanks much,
> +Ryan
> 
> 
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/



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RE: [LARTC] Artificial latency

[lartc]

hello ryan,

> So, I used the nistnet module to delay incoming UDP packets
> to 192.168.1.4 by 300 milliseconds, and got the 'symmetric' delay I was
> seeking and faxes are working!
good news, alhtough I am curious how you are connected to the internet?
also, did you check with cisco?

> I am wondering if anyone out there can think of another delaying solution
> using a qdisc??   
i am not aware but would also be interested -- please do post back
should you find anything ...

> I had many problems getting the nistnet module installed;
> it refused to coexist with an lt_serial module that allows my faxmodem to
> work, and causes sporadic fits with my kernel.
yes, i experienced similar issues, but managed to get it stable for some
very simple testing -- i need to do more.

cheerio

charles

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