From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Fri Oct 17 2003 - 18:57:42 GMT-3
Jason,
This is assuming there is literally *no* other traffic on the
line. If the video application is really the *only* traffic on the
line, then QoS will not help. If that is so it's either a higher layer
(application) problem or a lower layer (physical) problem in this
particular case.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: Kleberg, Jason [mailto:JKleberg@glhec.org]
> Sent: Friday, October 17, 2003 4:47 PM
> To: 'Brian McGahan'; 'Jung, Jin'; Vazman@aol.com;
ccielab@groupstudy.com
> Subject: RE: Videoconferencing over IP
>
> Maybe I am missing something very fundamental here, and if I am please
> forgive my ignorance, but I still don't understand how any type of
qos
> will
> help if there is no congestion? Here is a quote from the cisco qos
pdf
> p121,
>
> "During periods with light traffic, that is, when no congestion
exists,
> packets are sent out the interface as
> soon as they arrive.
> "
>
> How can qos speed change this, that is make it go faster than "as soon
as
> they arrive"?
>
> Thanks
> jason
>
> -----Original Message-----
> From: Brian McGahan
> [mailto:bmcgahan@internetworkexpert.com]
> Sent: Friday, October 17, 2003 4:28 PM
> To: 'Kleberg, Jason'; 'Jung, Jin'; Vazman@aol.com;
> ccielab@groupstudy.com
> Subject: RE: Videoconferencing over IP
>
> Jason,
>
> Priority queues such as the legacy
priority-list,
> the low
> latency queue (LLQ), and IP RTP priority are constantly
in
> effect
> regardless of a congestion condition. The preferred
method
> to solve the
> aforementioned problem is the LLQ.
>
> LLQ guarantees that all packets in the priority
> queue are
> dequeued first up to the configured bandwidth value.
When
> packets in
> the priority queue exceed the configured bandwidth and
there
> is not
> congestion, excess packets are sent but not guaranteed
low
> latency.
> When the configured bandwidth is exceeded and there is
> congestion,
> excess packets are dropped. For this reason, the LLQ is
> considered a
> 'maximum' bandwidth guarantee. This offers a large
> advantage over the
> legacy priority queue since your non-priority traffic
cannot
> be starved
> of bandwidth.
>
> The IP RTP priority queue is effectively legacy
> because you get
> the same effect by issuing the 'match protocol rtp'
command
> in a
> class-map and putting this class into the priority
queue.
> Furthermore,
> you can configure an access-list in tandem which matches
> ranges of UDP
> ports.
>
> Vazman, try putting the video traffic in the LLQ
as
> suggested
> and see if this helps. If not, maybe there is some
trouble
> in the
> provider cloud with your circuit.
>
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 708-362-1418 (Outside the US and Canada)
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com
[mailto:nobody@groupstudy.com]
> On Behalf
> Of
> > Kleberg, Jason
> > Sent: Friday, October 17, 2003 6:33 AM
> > To: 'Jung, Jin'; 'Vazman@aol.com';
ccielab@groupstudy.com
> > Subject: RE: Videoconferencing over IP
> >
> > Why LLQ if there is no congestion? I think more
people
> could help if
> the
> > configs were posted. And if possible, some traffic
> history. IS there
> a
> > preferred method of QOS for this?
> >
> > thanks
> > jason
> >
> > -----Original Message-----
> > From: Jung, Jin [mailto:jin.jung@lmco.com]
> > Sent: Friday, October 17, 2003 6:25 AM
> > To: 'Vazman@aol.com'; ccielab@groupstudy.com
> > Subject: RE: Videoconferencing over IP
> >
> >
> > You need some sort of QOS enabled on your T1,, I used
LLQ,
> which seems
> to
> > be
> > working.
> >
> > Also, check you frame per second fps on your Video Con
> unit, I know
> some
> > PictureTel only support 15 fps,, You need to use
minium 30
> fps.
> >
> > Jin Jung
> > CCIE#12386
> >
> >
> >
> >
> > -----Original Message-----
> > From: Vazman@aol.com [mailto:Vazman@aol.com]
> > Sent: Friday, October 17, 2003 2:05 AM
> > To: ccielab@groupstudy.com
> > Subject: Videoconferencing over IP
> >
> >
> > Hello,
> >
> > Does anyone have any experience with using video
> conferencing over IP
> > (point-to-point or FR). We have a T1 between two sites
> with a
> PictureTel
> > on
> > each end. There is harldy any other traffic on the T1
but
> the quality
> of
> > the
> > video is not soo good (jitter etc). Audio has good
> quality.
> >
> > Thanks
> >
> >
>
>
This archive was generated by hypermail 2.1.4 : Mon Nov 24 2003 - 07:53:04 GMT-3