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New Member

Single Unity server w/ multiple AD/Exch2k sites

I've seen numerous posts about trying to use a single Unity server with multiple Exchange 5.5 sites and I understand that there is no way. However, I'm still not clear about AD/Exchange 2k implementations. If my customer has AD and multiple Exchange 2k servers in different sites, can Unity place messages into different servers? Having not worked with Exchange 2k very much, I'm not even sure if it is set up in different "sites" like Exchange 5.5 did. I know that in Exchange 2k there are Routing Groups and Administrative Groups but I'm not sure how Unity works with these and if it sees those as different "sites".


Re: Single Unity server w/ multiple AD/Exch2k sites

With Exchange 2000, Unity can service only a single routing group. Multiple domains, OUs and administrative groups are fine.


Re: Single Unity server w/ multiple AD/Exch2k sites

I'm not either a expert in Eschange 2K but, at least if you are using Unity 4.x you from the "Using Active Directory and Exchange 2000 for the Directory and Message Store" chapter in the unity design guide available in the web:

More than one Exchange 2000 routing group can reside within an administrative group. Cisco Unity can service users homed on multiple Exchange 2000 servers in more than one routing group in an administrative group. Connectivity between routing groups is an issue if the routing groups are connected via WAN connections.

And after this it indicates

A single Cisco Unity server should not service more than one administrative group regardless of the Exchange messaging mode being used.

I can't understand why, I suppose that is because of permissions in the active directory, because you can have different administrative groups into one site and this is not very extrange in Exchange 2k, deployments.



New Member

Re: Single Unity server w/ multiple AD/Exch2k sites

My customer has a large AD network with many sites. Each site has its own Exchange 2k routing group. My customer imported a user into the Unity server at site A even though the user's Exchange account is at site B in a separate routing group.

It looks like the user imported just fine so I am confused by what I have heard and what I am seeing.

In addition, I understand that Unity only being able to serve a single routing group is caused by a MAPI limitation so I was wondering if there is any documentation that could describe exactly why this would not work.

It seems to me that if Unity can "see" a user in AD and import him, it would be able to send a message to him through Unity's partner Exchange server, which is networked to the rest of the Exchange servers. Since the user was imported, what kind of problems could be expected if they tried to use this account?

I'm just trying to understand this better so I can explain it to my customer instead of just telling them "it's not supported".


Re: Single Unity server w/ multiple AD/Exch2k sites

It's not a question of working or not. Technical it can work. The issue is with it scaling which it cannot. Prior to Unity 4.0(4) and Exchange 2000 post-SP3 6556.5 / Exchange 2003 SP1 all of the MAPI interaction was serial which meant that if a MAPI call to a remote server was hanging because of packet loss, delay, low throughput, etc everything would backup behind it. Since Unity requires real-time access to Exchange frequently the queue could build very deep and the system would be great impacted. In fact if it got really bad Unity would actually stop answering calls all together.

A bunch of this stuff has been changed in 4.0(4) to help correct a large number of the issues but we still won't support it because we haven't designed in enough of a buffer to protect the core system.



New Member

Re: Single Unity server w/ multiple AD/Exch2k sites

Thanks, Keith. This does help. I am still unclear, though, about why the queue could fill up if the mail server was remote. Doesn't Unity send all the messages through its partner Exchange server? If the partner server is local to Unity, doesn't Exchange actually take care of the delivery to the remote system?

I could understand this if the remote user was dialing in to the Unity server to check his messages and Unity could not open the remote mailbox for whatever reason but I am trying to understand where exactly the problem would occur. If the subscriber was unified and would only be checking messages from Outlook, would this work?

Also, just so I understand, it's not really a limitation of Exchange servers being in different sites or routing groups, it has more to do with the fact that most of the time, the links between different sites/RGs are slow, relatively unreliable WAN links, correct? If this were, for example, redundant Gig Ethernet or OC-3s between sites, then there should be no problem, right?

I understand now that I will still have to tell my customer that this is unsupported but the previous questions are more for my own knowledge.

Any idea if/when this will ever be supported? I have run into this several times over the past couple of years.

Thanks again for your help.