dear marcel

On Mon, 11 Apr 2005 13:49, Marcel.Leuenberger@BIT.admin.ch wrote:

Has anyone experience with a tool to simulate delays in packet forwarding - Especially to simulate high delays as they occur in satellite networks? Have anyone already used a free tool based on linux, freebsd, (windows).

check out nist net [1]. it's running on linux as a kernel module. in it's original version it has some limitations. it can only generate constant delays or delays of a small random table in the kernel. if that's not enough and you need to model correct statistical properties of network traffic such as long-range dependence, then you should take my extendend version of nist net which works with pregenerated trace data. i did my master's thesis on "Trace-based network emulation".

if you need further information, please contact me offlist.

[1] http://www-x.antd.nist.gov/nistnet/

Marcel Leuenberger writes:

Has anyone experience with a tool to simulate delays in packet

Nitpick... I think you mean "introduce artificial" or "emulate" rather than "simulate". For network simulation you could use something like the NS2 Network Simulator, which I'm sure has arbitrarily configurable delays/losses etc. per link.

forwarding - Especially to simulate high delays as they occur in satellite networks? Have anyone already used a free tool based on linux, freebsd, (windows).

Most people seem to use Dummynet for FreeBSD: http://info.iet.unipi.it/~luigi/ip_dummynet/

For Linux, there's NIST NET: http://cs.ecs.baylor.edu/~donahoo/tools/nistnet/

For Solaris, there's ONE (Ohio Network Emulator): http://masaka.cs.ohiou.edu/one/

Note that I don't have personal experience with any of these, but I know that at least Dummynet and NIST NET have succefully been used for research...

Regards,

On Mon, Apr 11, 2005 at 01:49:14PM +0200, Marcel.Leuenberger@BIT.admin.ch wrote:

Hiya!

Has anyone experience with a tool to simulate delays in packet forwarding - Especially to simulate high delays as they occur in satellite networks? Have anyone already used a free tool based on linux, freebsd, (windows).

there's also a "network emulator" module in linux 2.6.9 and later. sch_netem. you need a recent "tc" tool which sometimes corrupt itself automagically on the way from the server to your workstation, just for the fun of it. sorry I have mental health problems, of course.