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Carlos,<br>
<br>
'Registration' and timing appears to be topic-de-jure, this is the 4th
conversation about it already today. <br>
<br>
There are at least 2 factors at play when it comes to registration.
Let me expand on those:<br>
1. TCP session errors - SCCP/Skinny works over TCP/IP. When TCP
transmits a segment that segment must be acknowledged by the peer. In
the case of an SCCP keepalive exchange:<br>
phone cm<br>
-> sccp ka <br>
<- tcp ack<br>
< sccp ka ack<br>
-> tcp ack<br>
<br>
Normal TCP retransmit rules apply. Normal TCP session management also
apply. TCP FIN/RST can abort the session. ICMP messages such as host
unreachable, net unreachable, port unreachable, may also apply.
Otherwise the phone/CM will retransmit until TCP MaxRetransmits. On
the 7940/60 TCP will retransmit up to 5 times for a maximum of 15
seconds (this was the last value i have documented, it may have
changed). On the 3rd gen phones 7941,61,70,71,42,62, etc the maximum
retransmit time is much shorter. I've seen reports as short as 4
retransmits each after 300 ms (less than 2 seconds total). I do not
have hard numbers handy on those.<br>
<br>
If you have an outage of 15 seconds at the exact instant when phone
needs to send SCCP keepalive then the phone is going to unregister and
report "CM down features disabled". The TCP/IP network must be stable
and working.<br>
<br>
2. keepalive errors - This is complete implemented at the SCCP level,
so above TCP. CM allows missing 2x keepalives from the phone, most
SCCP endpoints support missing 1 SCCP KeepAliveAck from CM. These are
not universally supported as seen in CSCef31887.<br>
<br>
The vast majority of time we see:<br>
Phone believes it failed because of TCP timeout, TCP reset, or TCP
fin. This is normal since the phone is responsible for initiating SCCP
KA. It has to send data over the network and has to receive a response.<br>
CM believes the phone failed because of "device initiated reset" or
"keepalive timeout". "device initiated reset" is a misnomer, see
CSCsa66536. CM is sitting waiting to receive SCCP KA from the phone.
When the phone does not send then CM aborts the session. Note CM
institutes timeout at the SCCP level (~90 seconds) while the phone
institutes timeout at the TCP level (~15 seconds).<br>
<br>
/Wes<br>
<br>
<a class="moz-txt-link-abbreviated" href="mailto:CarlosOrtiz@bayviewfinancial.com">CarlosOrtiz@bayviewfinancial.com</a> wrote:
<blockquote
cite="mid:OF6BE51832.2068615A-ON852573E6.005CC55F-852573E6.005D229C@bftg.com"
type="cite"><br>
<font face="sans-serif" size="2">Not the case here as this Subscriber
has many other phones registered is the US with no problems. As Wes
said,I suspect a network issue, but I was hoping to change the
keepalive
timer for those phones to decrease the chance that a single missed
keepalive
would cause the message to appear and invoke a failover. This way
when a someone hangs up the phone a failover would not be invoked
automatically.
That's my understanding of the process anyway......</font>
<br>
<br>
<font face="sans-serif" size="2">Carlos</font>
<br>
<br>
<br>
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<td width="40%"><font face="sans-serif" size="1"><b>Robert
Kulagowski <a class="moz-txt-link-rfc2396E" href="mailto:rkulagow@gmail.com"><rkulagow@gmail.com></a></b>
</font><br>
<font face="sans-serif" size="1">Sent by:
<a class="moz-txt-link-abbreviated" href="mailto:cisco-voip-bounces@puck.nether.net">cisco-voip-bounces@puck.nether.net</a></font>
<p><font face="sans-serif" size="1">02/05/2008 11:50 AM</font>
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<div align="right"><font face="sans-serif" size="1">To</font></div>
</td>
<td><font face="sans-serif" size="1"><a class="moz-txt-link-abbreviated" href="mailto:cisco-voip@puck.nether.net">cisco-voip@puck.nether.net</a></font>
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<div align="right"><font face="sans-serif" size="1">cc</font></div>
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<td>
<div align="right"><font face="sans-serif" size="1">Subject</font></div>
</td>
<td><font face="sans-serif" size="1">Re: [cisco-voip]
Phone Keepalives</font></td>
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<br>
<br>
<br>
<font size="2"><tt>Wes Sisk wrote:<br>
> sccp keepalive interval is a cluster wide parameter.<br>
> <br>
> Sounds like you definitely have spotty network connectivity. Have
to <br>
> stabilize that.<br>
<br>
But couldn't it also be a runaway process that's hogging CPU? I just
<br>
ran into a situation where a javaw process was spiking to 100% often <br>
enough that phones connected to that subscriber were showing "CM Down".<br>
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