about "profile" in IPFW/dummynet

Luigi Rizzo rizzo at iet.unipi.it
Thu Feb 10 07:30:15 UTC 2011


On Thu, Feb 10, 2011 at 12:09:09AM +0000, nangergong wrote:
> Hi, all:
> 
>    I want to use "profile" to simulate delays according to a empirical delay
> distribution ( the "profile" argument can be found in
> http://fuse4bsd.creo.hu/localcgi/man-cgi.cgi?ipfw+8)
> I use the following command lines and distribution.txt, and find that these
> command lines seem not to  function. when I ping 9.161.148.72, the RTT<1ms
> 
> My question is
> 1) can "profile" be used in windows platform
> 2) are there any problems in my procedures?

you need a non-zero bandwidth if you want to use "profile".
Also, "profile" emulates an additional transmission time
(think of channel arbitration and mac overheads)
not propagation delay.

Finally I believe profile works on all supported platforms.
In general, the differences between FreeBSD/linux/windows are
only in areas where certain kernel features are implemented
in different ways on different platforms -- e.g. sysctl,
reinjection, matching on pid/gid or other credentials, divert.

cheers
luigi
> 
> 
> my command lines are:
> 
> ipfw pipe 1 config profile distribution.txt
> ipfw add 100 pipe 1 ip from 9.161.150.55 to 9.161.148.72
> --------------------------------------------------------------------------------------
> if I input: ipfw pipe show
> 
> the result is:
> 
> 00001: unlimited         0 ms burst 0
>          profile: name "distribution" loss 0.850000 samples 100
> q131073  50 sl. 0 flows (1 buckets) sched 65537 weight 0 lmax 0 pri 0
> droptail
>  sched 65537 type FIFO flags 0x0 0 buckets 0 active
> 
> 
> the content of distribution.txt is:
> 
> name    distribution
> samples 100
> loss-level    0.86
> prob    delay
> 0       200     # minimum overhead is 200ms
> 0.5     200
> 0.5     300
> 0.8     1000
> 0.9     1300
> 1       1300
> #configuration file end
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