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Each ccm process is a concurrent real time process. They exchange
messages as needed over SDL links. In addition to that realtime
communication there are keepalives every 10 seconds. The real time
synchronization makes these links the most sensitive TCP sessions in
the network.<br>
<br>
At the same time it is necessary to detect dead links as quickly as
possible. A call may be held up on node1 pending a response from
node2. A bandwidth reservation request on node1 must synchronize
with all nodes as quickly as possible to avoid potential over
subscription.<br>
<br>
To that end a network outage as low as ~ 2 seconds can cause SDL
link out of service. The value can be even lower depending on RTT
in your network. See:<br>
<a class="moz-txt-link-freetext" href="http://www.faqs.org/rfcs/rfc793.html">http://www.faqs.org/rfcs/rfc793.html</a><br>
<br>
These parameters are not configurable on CUCM.<br>
<br>
<br>
At what interval is your network service monitoring network
connectivity? They need to get down to the order of single seconds
for monitoring to correctly detect outages that will affect CUCM.<br>
<br>
Regards,<br>
Wes<br>
<br>
<br>
<br>
On 1/25/2011 3:50 PM, <a class="moz-txt-link-abbreviated" href="mailto:steve.siltman@assurant.com">steve.siltman@assurant.com</a> wrote:
<blockquote
cite="mid:OFAA0270FF.F88C8BFE-ON86257823.00720223-86257823.00727386@assurant.com"
type="cite"><font face="sans-serif" size="2">Hey All!</font>
<br>
<br>
<font face="sans-serif" size="2">Quick one for you.</font>
<br>
<br>
<font face="sans-serif" size="2">Four of our Call Manager clusters
are
split between two locations. All received the
SDLLinkOutOfService
message. I have no doubt that we had a network issue of some
sort
that prevented these clusters from talking to each other for a
few seconds.
Our Network services area was unable to find this network burp.
I
want to understand this message a little better. Do you know
what
the timer is for the SDL packets between the call manager
servers and whether
or not this can be massaged?</font>
<br>
<br>
<font face="sans-serif" size="2">Thanks,</font>
<br>
<font face="sans-serif" size="2"><br>
-Steve<br>
</font>
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