Integrating Presence with multiple AD/Exchange Domains

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Jan 22nd, 2010
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We have a single CUCM cluster that support several organizations.  Some of these organizations want to implement CUPS with integration with their Exchange Servers.  Each organization has their own, seperate AD Tree and Exchange server (some integrate with their own Unity, some others have their own Unity Connection server).  However, Presence only allows a single Outlook Presence Gateway for Free/Busy indication.   This is a problem.


One thought is that each organization get their own Presence server, but can non-clustered Presence servers integrate with one CUCM cluster?  I know that a single Presence Cluster will not support multiple CUCM clusters, but does it have to be a 1-to-1 relationship?


Second, can different Presence servers in the same cluster point to different Outlook Presence Gateways?  If so, we can simply add a Presence server for each organization that points to that org's Exchange server.

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htluo Sun, 01/24/2010 - 06:49
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The answer is yes and no.


Yes, you may install multiple CUPS servers with one CUCM cluster.  You may point each CUPS server to different Exchange server.


Most of the features will work but phone presence ("on-the-phone" status).  Because on CUCM, you can only specify one SIP trunk as PUBLISH trunk.  And one SIP trunk can only point to one CUPS server (cluster).


There might be some "workarounds".  But I haven't tested them yet.  So it might or might not work.


Workaround 1:  Set up a "proxy device" to redirect traffic.  All CUPS server point to this device.  This device will redirect the traffic based on difference email domain.  This device could be a layer 7 content switch, an Exchange server, or a firewall/web proxy with content inspection features.


Workaround 2: On CUPS > Presence > Settings, uncheck "Enable SIP Publish on CUCM".  Without this option, CUPS will use SUBSCRIBE/NOTIFY model to get phone presence from CUCM.  You don't have to specify a PUBLISH trunk on CUCM.  This works on CUCM 5.x.  But I haven't tested on CUCM 6.x or above.


Ultimate Solution: talk to a Cisco sale person and request multi-tenant feature to be added to CUPS.  You're not the first one who asked for this.  Development team just wait for enough requests to justify the decision.


Michael

http://htluo.blogspot.com

CHRIS CHARLEBOIS Mon, 01/25/2010 - 10:07
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Thanks, Michael.  I'm trying to understand how the SUBSCRIBE/NOTIFY method works and how I can implement it instead of the SIP Trunk PUBLISH method.  Do you know of any decent references that could provide that info?  Is there an SRND specific for Presence?  The section on Presence in the CUCM 6.X SRND was pretty basic.

lpratt Mon, 01/25/2010 - 15:37
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The SUBSCRIBE/NOTIFY from CUCM to CUP is the default option on install.

The administrator has to enable the CUP PUBLISH Trunk for PUBLISH to be

used.  There is a one to one relationship of CUP clusters to CUCM clusters;

therefore, more than one CUP cluster to a CUCM cluster is an unsupported

configuration.


The difference between SUBSCRIBE/NOTIFY and PUBLISH is the number of

messages on an update.  With PUBLISH, CUCM and CUP both know the user

is assigned and liscensed so on a state change the PUBLISH is sent from

CUCM to CUP and CUP sends a 200 OK acknowledgement.  With SUBSCRIBE/

NOTIFY, CUP initiates a SUBSCRIBE for the user from CUP to CUCM, and CUCM

sends a 200 OK acknowledgement, and then on any state change CUCM will send

a NOTIFY to CUP and CUP will answer with a 200 OK acknowledgment.


CUP today supports a single domain.  Intergation with multiple domains is

handled through inter-domain federation.


The link to the SRND is here:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/7x/presence.html


Louis

CHRIS CHARLEBOIS Mon, 01/25/2010 - 12:54
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Is it possible to create a SIP PUBLISH Trunk to one CUPS from our CUCM cluster, and then share the phone presence information to other CUP servers through an Inter-Domain Federation?  The other CUPS would not be clustered together, so that each could be connected to a different Outlook Gateway pointed to a different Exchange server/cluster.  Is this a better solution than trying to get the SUBSCRIBE/NOTIFY method to work with CUCM 6.X?   I am also worried that even if we get it to work with CUCM 6.X, it will break under 7.X or 8, when it comes time to upgrade.


EDIT:  Thinking about this further, it doesn't work.  The Federation provides Presence information on foreign users.  I don't think it would be possible to corelate the Exchange free/busy info with the external presence status because they would be considered two different entities (one local, the other foriegn)

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