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...
