[Asterisk-Users] QoS in asterisk

[Paul Mahler]

Well, the question may not have been about QoS, but my answer certainly was.
QoS is defined as "The performance specification of a communications channel
or system. (188) Note: QOS may be quantitatively indicated by channel or
system performance parameters, such as signal-to-noise ratio (S/N), bit
error ratio (BER), message throughput rate, and call blocking probability."

Quality of Service (QoS) is a general term for an abstraction covering
aspects of the non-functional behavior of a system, for example delay. 

I think what we have here is what we are going to see a lot of--cultures in
collision. The PSTN folks had QoS issues long before it became an IP issue. 

I think what you are alluding to is routing specific IP QoS. IP supports QoS
in the IP header, those pesky tos bits you were talking about. Asynchronous
transfer mode (ATM) natively provides QoS. The IEEE 802.1p standard covers
QoS in all IEEE 802-type networks.

Even in networking, QoS is first and formost an abstraction before it
becomes a specification. "QoS is the ability of a network element (e.g. an
application, a host or a router) to provide some level of assurance for
consistent network data delivery."

QoS is most certainly an issue when making the decision to move off the
PSTN. Is the performance of your VoIP system going to be comparable to the
performance of your PSTN system? Sounds like a reasonble question to me. 




Paul Mahler 
pmahler at signate.com 	
Signate, LLC
665 Third Street
Suite 100
San Francisco, CA
 94107-1901

 Asterisk Services and Training

 

 

 

 

> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com 
> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of 
> Stephen J. Wilcox
> Sent: Sunday, July 11, 2004 3:33 PM
> To: asterisk-users at lists.digium.com
> Subject: RE: [Asterisk-Users] QoS in asterisk
> 
> Both the question and the answer are not talking about QoS.
> 
> >From the Q, qos does not provide a measure of quality, it provides a 
> >system to
> allow you to request your data be handled according to priorities.
> 
> >From the A, qos is confused with the pstn.. qos is a feature of IP, 
> >that has
> nothing to do with the pstn. jitterbuffer isnt qos either, 
> altho its important you get it right to provide good quality calls.
> 
> qos is the tos options you can specify in the conf files but 
> you need to combine that with routers from server to client 
> that will honor the tos you set. 
> 
> deciding to switch from voip to pstn wouldnt be covered by 
> qos, you would need to find other ways.. playing with options 
> like 'qualify' to timeout poorly connected devices quickly is 
> more like what you are trying to achieve.
> 
> Steve
> 
> On Sun, 11 Jul 2004, Paul Mahler wrote:
> 
> > This is a very complex question. 
> > 
> > First, you have to ask about VoIP and QoS. This is because 
> * uses VoIP 
> > protocols like UDP and RTP. In general, the QoS of VoIP is 
> not as high 
> > as with the PSTN. Even so, call quality can be generally very good.
> > 
> > Second, * does support features that support QoS, for 
> example the IAX 
> > jitterbuffer setting.
> > 
> > 
> > Paul
> > 
> > 
> > Paul Mahler 
> > pmahler at signate.com 	
> > Signate, LLC
> > 665 Third Street
> > Suite 100
> > San Francisco, CA
> >  94107-1901
> > 
> >  Asterisk Services and Training
> > 
> >  
> > > Does asterisk provide quality of service(QoS)? If it 
> does, how do I 
> > > use it? The reason why I ask is that I need to switch to use POTS 
> > > should the internet connection becomes poor?
> > > 
> > > Thanks,
> > > Jim
> > > 
> > > 
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