[LARTC] Delay packets by 50ms

[LARTC] Delay packets by 50ms

[Anshuman Kanwar]

Hi all,

I am trying to solve a tiny problem that is trivial to
solve using dummynet (FreeBSD). 

I just want to add a delay of 50ms to each outgoing
packet from an interface. This is to simulate a large
pool of multiple modem users so I also need to add b/w
limits etc (which seems to be easy to do).

From the mailing list I could fine 2 qdiscs that can
simulate latency : "delay" & "netem". Neither of them is
working on my setup though ( Fedora core2 [2.6.5] or RHEL
3.0 update 2 or gentoo [2.6.8] ). Is something special
needed to enable these qdiscs ?

I tried applying the patch
(http://www.uwsg.iu.edu/hypermail/linux/net/0403.2/0019.h
tml) and recompiled the kernel but the tc command returns
"RTNETLINK answers: Invalid argument".

What am I doing wrong ? 

Thanks much,
-ansh


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Re: [LARTC] Delay packets by 50ms

[Stephen Hemminger]

On Fri, 2004-10-08 at 15:38 -0700, Anshuman Kanwar wrote:
> Hi all,
> 
> I am trying to solve a tiny problem that is trivial to
> solve using dummynet (FreeBSD). 
> 
> I just want to add a delay of 50ms to each outgoing
> packet from an interface. This is to simulate a large
> pool of multiple modem users so I also need to add b/w
> limits etc (which seems to be easy to do).
> 
> >From the mailing list I could fine 2 qdiscs that can
> simulate latency : "delay" & "netem". Neither of them is
> working on my setup though ( Fedora core2 [2.6.5] or RHEL
> 3.0 update 2 or gentoo [2.6.8] ). Is something special
> needed to enable these qdiscs ?

delay was my earlier name, netem is the current one.

Netem went in to mainline kernel 2.6.8 (also 2.4.27)



> I tried applying the patch
> (http://www.uwsg.iu.edu/hypermail/linux/net/0403.2/0019.h
> tml) and recompiled the kernel but the tc command returns
> "RTNETLINK answers: Invalid argument".

You probably need to build/run newer version of tc 
see http://developer.osdl.org/dev/iproute2

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RE: [LARTC] Delay packets by 50ms

[Anshuman Kanwar]

Hi Stephen,

Getting the latest iproute2 solved my problem.

Thanks! 

-----Original Message-----
From: Stephen Hemminger [mailto:shemminger@osdl.org] 
Sent: Friday, October 08, 2004 3:55 PM
To: Anshuman Kanwar
Cc: lartc@mailman.ds9a.nl
Subject: Re: [LARTC] Delay packets by 50ms

On Fri, 2004-10-08 at 15:38 -0700, Anshuman Kanwar wrote:
> Hi all,
> 
> I am trying to solve a tiny problem that is trivial to
solve using 
> dummynet (FreeBSD).
> 
> I just want to add a delay of 50ms to each outgoing
packet from an 
> interface. This is to simulate a large pool of multiple
modem users so 
> I also need to add b/w limits etc (which seems to be
easy to do).
> 
> >From the mailing list I could fine 2 qdiscs that can
> simulate latency : "delay" & "netem". Neither of them
is working on my 
> setup though ( Fedora core2 [2.6.5] or RHEL 3.0 update
2 or gentoo 
> [2.6.8] ). Is something special needed to enable these
qdiscs ?

delay was my earlier name, netem is the current one.

Netem went in to mainline kernel 2.6.8 (also 2.4.27)



> I tried applying the patch
>
(http://www.uwsg.iu.edu/hypermail/linux/net/0403.2/0019.h
> tml) and recompiled the kernel but the tc command
returns "RTNETLINK 
> answers: Invalid argument".

You probably need to build/run newer version of tc see
http://developer.osdl.org/dev/iproute2
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