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Posted by Stephen Sprunk on May 29, 2006, 12:57 pm
If you were Registered and logged in, you could reply and use other advanced thread options > R-Guy wrote:
>> >I have a pair of Cisco 3725 routers that I'm talking through
>> > using VOIP. I measured a mouth to ear delay of 70ms with a
>> > standard config. Is this what I should be getting? Is there a way
>> > to make the delay 0?
>> >
>>
>> Are they connected by LAN or WAN?
>> What codec and packetization period are you using?
>> What type of voice terminal are you using?
>
> LAN,
>
> G.711 ulaw 20ms,
>
> standard POTS phone
With 20ms packetization, it will be impossible to get less than 20ms delay,
because that's how much data the gateway has to collect before sending a
packet. There's also typically 10-20ms burned in the codec/DSP's pipeline.
On top of that, the receiver's jitter buffer will add a few tens of ms; most
jitter buffers, even adaptive ones, are tuned with a minimum of a few tens
of ms because it doesn't hurt, and 40ms or so of buffering will hide all but
the worst unless you have no QoS at all over a skinny WAN pipe.
70ms isn't bad, and no human should ever notice it. Don't worry about
latency until it hits 150ms.
S
--
Stephen Sprunk "Stupid people surround themselves with smart
CCIE #3723 people. Smart people surround themselves with
K5SSS smart people who disagree with them." --Aaron Sorkin
*** Posted via a free Usenet account from http://www.teranews.com ***
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