[cisco-voip] Call Control / Phone Registration Distance

[Wes Sisk]

Good catch.

That depends on users and setting expectations.

It is dependent on the protocol in use. H.323 users will be impacted at 
lower RTT as more packets re required to setup a call. Going way back in 
time to
CSCdv68263 No windowing of h245 delays audio cutover in high roundtrip 
network

This happened at 170msec RTT with H.323.  We could never get H323 fast 
enough to avoid negative user experience ("hello, thank you for calling" 
becomes "you for calling").  Moving to MGCP significantly improved 
performance.

On the client side SCCP performs better than SIP as it is less chatty, 
there is some commentary here:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/netstruc.html#wpmkr1045581

SIP and SCCP will "work" (YMMV) at some pretty extreme delays (~1 
second) but user experience is poor. 

I don't see the comps documented on Cisco.com but they are available 
through your Cisco account team.

/Wes




On Friday, August 20, 2010 5:48:41 PM, Nate VanMaren 
<VanMarenNP at ldschurch.org> wrote:
>
> Wes,
>
>  
>
> My understanding of G.114 is only for the audio path.  I think this 
> question is more for the control path.  What is the user-acceptable 
> latency between the Call Agent and the Endpoint.  Say I have two 
> phones on the same network, but the call agent is 500ms one way.  Will 
> the users be happy with the delay to dial tone and delay in audio 
> connection setup.
>
>  
>
> I have not found information about this in the SRND.
>
>  
>
> -Nate
>
> *From:* cisco-voip-bounces at puck.nether.net 
> [mailto:cisco-voip-bounces at puck.nether.net] *On Behalf Of *Wes Sisk
> *Sent:* Friday, August 20, 2010 3:27 PM
> *To:* H, Tim
> *Cc:* cisco-voip at puck.nether.net
> *Subject:* Re: [cisco-voip] Call Control / Phone Registration Distance
>
>  
>
> I believe the SRND speaks to this.  It should point to G.114 for 
> recommended RTT for user experience.  Above 150msec user experience 
> begins to deteriorate. 
>
> /Wes
>
> On Friday, August 20, 2010 4:15:10 PM, H, Tim <TimH at trstone.com> 
> <mailto:TimH at trstone.com> wrote:
>
> All,
>
>  
>
> Does Cisco give a limitation on Distance/Latency on how far away from 
> a CUCM cluster you can be before they don't support phone 
> registration/call control?
>
>  
>
> I haven't been able to find documentation, but if someone knows where 
> to find that, it would be very helpful to me.
>
>  
>
> Thanks,
>
>  
>
> *Tim *
>
>  
>
>  
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>  
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