From: Mark Snow (msnow@ipexpert.com)
Date: Tue Oct 16 2007 - 23:07:51 ART
And to add to that - your packets may be marked with the DE bit set
to 1 and eventually optionally dropped - and that is BAD for voice :)
No retransmission for dropped RTP (UDP) packets.
Mark Snow
CCIE #14073 (Voice, Security)
CCSI #31583
Senior Technical Instructor - IPexpert, Inc.
A Cisco Learning Partner - We Accept Learning Credits!
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On Oct 16, 2007, at 9:32 PM, Wink wrote:
> The thought behind this is that while voice traffic is present, you
> will not exceed the rate that telco guarantees you. (Which telco
> calls your CIR, and Cisco calls your mincir).
>
> You don't want to exceed your guaranteed rate when voice traffic is
> present, because it may cause telco to queue your packets in
> intermediate carrier node buffers (atm switches, frame switches,
> MPLS nodes providing AToM services, etc), thus impacting voice
> negatively.
>
>
>
>
> ----- Original Message ----- From: "Mark Mahan" <mmahan@caprock.com>
> To: "Navid Daghighi" <daghighi.navid@free.fr>; "Cisco
> certification" <ccielab@groupstudy.com>
> Sent: Tuesday, October 16, 2007 1:55 PM
> Subject: RE: frame relay voice adap
>
>
>> I believe it eliminates the possibility of jitter caused by variable
>> transmission rates as PVC traffic shaping rates are throttled down
>> from
>> the CIR when you get a BECN and ramp back up after a period no
>> congestion. With traffic locked at the minCIR rate when voice
>> traffic
>> is present, you have a steady rate and since RTP should be in a PQ,
>> little jitter.
>>
>>
>>
>> Mark Mahan
>> Network Engineer
>> -------------------------------
>> CapRock Communications
>> 4400 S. Sam Houston Parkway E.
>> Houston, Texas 77048
>> Office: 832 668 2528
>> mmahan@caprock.com
>> www.caprock.com
>>
>>
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>> -----Original Message-----
>>
>>
>>
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
>> Behalf Of
>> Navid Daghighi
>> Sent: Monday, October 15, 2007 5:17 PM
>> To: Cisco certification
>> Subject: frame relay voice adap
>>
>> Hi,
>>
>> Cisco doc says :
>>
>> "Frame Relay voice-adaptive traffic shaping enables a router to
>> reduce
>> the permanent virtual circuit
>> (PVC) sending rate to the minimum CIR (minCIR) whenever packets
>> (usually
>>
>> voice) are detected in the
>> low latency queueing priority queue or H.323 call setup signaling
>> packets are present."
>>
>> Why would it be useful to reduce the sending rate, when there are
>> packets in a priority queue ?
>>
>>
>> Thanks,
>> Navid
>>
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