Olivier,

For IP impairments, I'm using some linux machines playing
router/firewall/impairment-generator/DHCP-server/etc in between the CPE
and the server, so I'm not doing it on the CPEs or SIPP-machine itself.

Interfaces up/down can be physical or vlan-based, and get a simple per
interface netem setting, giving a different behaviour per direction.
Beware, basically netem only works on the packets leaving the machine.
And take care you never put too many impairments on your management
link;-)

The wiki information on impairments can be found at
http://en.wikipedia.org/wiki/Network_emulation and the one on netem on
http://linux-net.osdl.org/index.php/Netem , and the info is rather good,
the netem examples even go farther then what I'm using.

  Best regards,

   MarcVD

-----Original Message-----
From: Olivier Jacques [mailto:[EMAIL PROTECTED]
Sent: 26 October 2006 11:50
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]; [email protected]
Subject: Re: [Sipp-users] sipp defunct processes + IP impairments

[EMAIL PROTECTED] wrote:
> Vlad,
> 
> on defunct:
> -----------
> you're right, it's the way daemons and backgrounding is done, and
> solves the "defunct" issue. So, the ideal bug fix.
> 
> I have some problems though with the final result we get, but those
> are not breaking to use this solution now:
> 
> 1. to execute a (small) unix program, we will use "fork - fork -
> system", that gives three process creations instead of one (but we
> already had two in the code;-), it's certainly not optimal/efficient,
> but computers are fast with a lot of resources these days.
> 
> 2. making an orphan of the final child process gives them ppid=1,
> making tools like pstree and pkill fail to identify the correct child
> processes. When running multiple instances of sipp (as I do), it might

> give problems to handle all processes hanging around (cleanup when
> things don't go like you expected).
Ok. Not an ideal situation, but better...
> 
> Olivier,
> 
> on IP impairments:
> -----------------
> 
> I noticed you proposing NISTNET as impairment generator on linux, but
> if my info is correct, most people nowadays have switched to NETEM,
> which is integrated in the standard linux kernel (you might have to
> activate it when compiling). Netem is only one of the tools available
> in a more general scheme, which also support chaining with packet
> classifiers, queues and shapers. Very powerfull, I only used the basic

> impairments until now (per direction drop, duplicate, delay/jitter).

Thanks! I didn't know about NETEM, I'll definitely have a look.
Would you like to add some info on the specific usage of NETEM in the
context of SIP+RTP on SIPp's wiki? (http://sipp.sourceforge.net/wiki/)

--
Olivier
HP OpenCall Software
http://www.hp.com/go/opencall/




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