[VOIPSEC] QoS vs VoIP security

Panos Koutsougeras pkoutsougeras at gmail.com
Sun Apr 23 09:06:52 PDT 2006


The voipsa threat document (
http://www.voipsa.org/Activities/VOIPSA_Threat_Taxonomy_0.1.pdf) on page 33
says this:

"Performance Metrics
To be considered as providing same or better than toll quality telephony
service
provided by the PSTN, the following media performance metrics are defined in
ITU-T-G113 and ITU-T-G114:

· Latency < 150 ms
A latency of 150ms – 200ms, though usable, results in 'choppy' media
exchange.
Latency greater than 200ms, is typically considered unusable as delays
prevent
normal 'conversation'.

· Jitter < 25ms
Buffering at the receiver can reduce the effect of jitter.
Excessive jitter introduces delays and affects media exchange in similar
ways as
latency.

· BER < 0.25%, Packet Loss < 0.5%
As media typically uses UDP, an unreliable IP transport protocol, there is
only
limited recovery from packet errors and loss. Packet loss below the
specified
threshold is usually imperceptible. Excessive packet loss introduces delays
and
affects media exchange in similar ways as latency."



Does everyone agree with these ITU guidelines in their own practice?  Or
does it vary wildly based upon the particular application, device, codec,
etc?


Panos




On 4/19/06, Sergey Vointsev <vointsev at gmail.com> wrote:
> > In this moment i'm working in my PhD Thesis "QoS vs VoIP security"
> > Any person have any type of information in relation to the afectations
of
> > the Security (VPN, IPSec, IDS, Firewalls, SRTP, IPv6) in the diferents
> > parameter of the QoS (jitter, delay, MOS, etc)
>
> Have a look to Ethereal - open source traffic analysis tool.It can
> capture all traffic and give a lot of different information about each
> packet. The most interesting for you - it can analyse
> not only packets, but also entire RTP streams and give interesting
> statistics about packet loss, jitter, delay etc. All this data can be
> displayed as detailed graphical charts.
>
> --
> Also available for instant messaging via Google Talk.
> Need invite to Gmail? I have one for you! Just ask.
>
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