From: Kleberg, Jason (JKleberg@glhec.org)
Date: Fri Oct 17 2003 - 18:47:24 GMT-3
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