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What CM version are you on?<br>
<br>
Only recent optimization available is Advanced CM service parameter
"Bundle Outbound SCCP Messages Timer" to enable bundling of SCCP
messages. More messages per packet = fewer ACKs = fewer round trips.
Much further back there was an effort to streamline the number of
messages required to setup SCCP call.<br>
<br>
SCCP capabilities are exchanged at device registration so it does not
suffer the same issue as h.323 where capabilities must exchange during
every call setup. There is no MSD equivalent. SCCP overall is a much
lighter protocol at the point of call signaling. The only round trip
requirement in SCCP is OpenReceiveChannel/OpenReceiveChannelAck with
remote IP:Port. StartMediaTransmission is required and cannot be sent
until IP:Port is received from far end device. Unfortunately this
exchange is required with no way to bypass this round trip for SCCP.<br>
<br>
One area we commonly see issues is shared lines at remote sites. This
is covered in SRND:<br>
<a class="moz-txt-link-freetext" href="http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/netstruc.html#wp1045582">http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/netstruc.html#wp1045582</a><br>
<br>
Is it really RTT or is it possibly link speed that is causing the issue?<br>
<br>
/Wes<br>
<br>
<br>
<br>
On Monday, August 03, 2009 4:11:50 PM , Keith Klevenski
<a class="moz-txt-link-rfc2396E" href="mailto:KKlevenski@cstcorp.net"><KKlevenski@cstcorp.net></a> wrote:<br>
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<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";">Is
there any mechanism to ‘speed up’ skinny call setup like faststart
in h323? Satellite provider migrated to skinny gateways (SCCP
controlled FXS
ports) from h323 gateways. All analog phones. It was noticed that
inbound PSTN calls (through h323 gateway) were losing the first second
or so of
the call when the called party picked up. This made sense to me as the
skinny gateway must tell CM the phone has gone offhook then CM tells
the gateway
to tell the phone to stop ringing and send media stream to the PSTN
gateway. This is over a 600-700ms satellite link so the delay would be
reasonable. The rest of the call is perfect. If the same skinny
gateway is changed to h323 the delay is not present since h323 gets the
IP
address where to send the stream during call setup if I’m not mistaken
so
the delay isn’t present, but neither are the features of skinny
controlled
fxs ports…<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";">To
me this is all reasonable and makes perfect sense. The question the
customer
has is if there is any mechanism to speed up the skinny signaling. I
wouldn’t
think so based on the master/slave nature of the skinny protocol. I’ve
configured voice call send-alert, voice rtp send-recv, progress_ind
setup
enable 3, and all that, but nothing helps and I can understand why.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";">Can
anyone confirm if there is a way to speed up skinny call setup over
high
latency links? Running CM 7.0, SCCP controlled FXS.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 10pt; font-family: "Arial","sans-serif";">Thanks!<br>
<br>
-Keith <o:p></o:p></span></p>
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