Wireshark · Ethereal-users: Re: [Ethereal-users] RTP, jitter, delay, BW , are that valures calculated by ethereal good?

["Lars Ruoff" <Lars.Ruoff@xxxxxxxxxx>]

Hello,
i dont' answer directly to your questions below due to lack of time, but i
had a look at the file you sent me.
The problem with the reverse direction 192.168.1.100->192.168.1.101 is that
all packets have the marker bit set!
But packets with the marker bit are currently excluded from delay/jitter
calculation!
It may be worthwhile to discuss that on the general list.
best regards,
Lars Ruoff

----- Original Message ----- 
From: "Michael Mendoza" <michaelux@xxxxxxxxx>
To: "Ethereal user support" <ethereal-users@xxxxxxxxxxxx>
Sent: Saturday, April 08, 2006 1:34 AM
Subject: [Ethereal-users] RTP, jitter, delay, BW ,are that valures
calculated by ethereal good?


Hi, I dont write so mucho english but I will try..

I use ethereal 0.10.14 for capture traffic RTP for Voip, I am
analyzing  that traffic but I have some question, really ethereal
calculates  good values for the jitter, dealy and BW (in the Analysis
streams)? because I see somes values   , for example the BW (kbps) if
I use the GSM codec, the BW  for some packet is about 29 kbps, I think
that is good because the codec use that, I think than the BW must be
for every packet,BUT for the firts packet the BW is  2 kbps, 5 kbps, 8
kbps, almost the half have theses values, but the other half have 29
kbps, and that must be fine..Why happend this? is something wrong with
the ethereal? o am I ?

The other questions what I have is: The jitter for some packet is very
low, for example 0,2    0,14 ms but for the others packets this are
about 7 ms, 11,   15 ms and that is a good values, but 0,2 I think is
too low...I want to know how ethereal calculates the jitter and delta
or delay..In the RFC i see   D(i,j) = (Rj -Ri) - (Sj -Si) = (Rj -Sj)
-(Ri -Si)  but I want to know which  is the unit of the timestamp, the
arrival time is en ms but i dont know abot the time stamps.For
examplie:  i have 2 packet, how calculate the delta:

packet 26: arrival time: 17.026562 (Ri)             timestamp= 0
(Si)  (the firt packet RTP)
packet 28  arrival time: 17.046810  (Rj)           timestampt= 160  (Sj)

 have I to do:  D( i, j )= ( 17.046810 - 160 ) -  (17.026562  -0 )


is correct this?Are the units good? Am i doing something wrong?

The result if a negative value....or not?

Etheral say than the delta for the pàcket 28 is: 20,25 ms, the jitter:
0.02 ms BW  3.2kbps

Are this values good? why the BW is 3.2kbps?


Thanks...
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