Hi, We currently have an AD design with two sites (historically grown), each containing two DC's, one Exchange 2007 MBX server, and one Exchange 2007 CAS/HT server. Because it is needed to have a CAS server in each site that contains a MBX server, we have one in each AD site. One of those two is currently the only internet facing one, and requests for MBX's that are on the MBX server in the other site, are proxied to the CAS server in the other site. Because there is a very performant link between the two sites nowadays (200 Mbit), and we are sometimes experiencing issues with AD synchronisation (changes are replicated to slow, as the lowest interval is 15 min), we would like to change this inyo one big site. The question I have is, how will this affect the working of the CAS servers in there current setup (proxying)? Will I break anything? Do I need to adjust anything? Do I need to redesign the CAS servers? Thanks in advance for your input. Koenraad.

It would have been ideal if you created a CAS array in each site beforehand? You can create a single AD site and have both CAS servers in the same AD site. What I'd do is create an CAS array and make both CAS server members of the CAS array, then configure your RPCClientAccess attribute on your databases. Proxying shouldnt occur as the CAS and MBX servers will be in the same AD site Sukh

Isn't RPCClientAccess something from Exchange 2010? We are still running 2007.. So if I understand correctly, it will continue working, but the non-internet facing CAS will just be sitting there, doing nothing, unless I create a CAS Array and put both CAS servers in it?

Sorry, thought it was 2010, there are no CAS arrays or RPClientAccess values for 2007 Will this be the only internet facing site? Do you have OWA/OA published externally? Sukh

You are right, RPCClientAccess attribute is come in picture in exchange 2010. Keeping all CAS server in one site will not affect any issue or any configuration. Just keep them in Array and start using it.Anil MCC 2011,ITIL V3,MCSA 2003,MCTS 2010, My Blog : http://messagingschool.wordpress.com

Hi, Proxy will work with internet-face and non-internet face CAS servers. For your scenario, One CAS server will be internet faced, if CAS get request from user, it will not proxy the requst to the internal CAS server. So I recommend you to make NLB for CAS server. Or you can publish OWA via ISA related application. Be careful with the certificate that you used before. Load Balancing Exchange 2007 Client Access Servers using Windows Network Load-Balancing Technology – Part 1: Overview of Windows NLB Clusters http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part1.html Xiu

Alright, I think I understand: The non internet facing CAS will be useless since it will not get proxied requests for the MBX server that is in its (physical) site, since the internet facing CAS can now serve those requests because there is only one site. Correct? So to make use of the second CAS, I would need to use software or hardware load balancing. (Or if it were to be Exchange 2010, a CAS array) If I were to only use one CAS that serves both MBX servers, how would that affect performance when it needs to get the data from the MBX server in the other physical site, over the 200 Mbit line? Is it comparable to when the request is proxied to the other CAS? Or faster, since it eleminates one step (the other CAS)?

Both sites have internet connectivity, but since we have OWA/ActiveSync published through a reverse proxy (bluecoat at the moment, would like to replace this with an UAG), only one CAS is internet-facing. Can you internet face the other one was well? I guess not since you can only publish the OWA/ActiveSync to one CAS? Or, like mentioned before, you would need to load balance both?

Alright, I think I understand: The non internet facing CAS will be useless since it will not get proxied requests for the MBX server that is in its (physical) site, since the internet facing CAS can now serve those requests because there is only one site. Correct? So to make use of the second CAS, I would need to use software or hardware load balancing. (Or if it were to be Exchange 2010, a CAS array) If I were to only use one CAS that serves both MBX servers, how would that affect performance when it needs to get the data from the MBX server in the other physical site, over the 200 Mbit line? Is it comparable to when the request is proxied to the other CAS? Or faster, since it eleminates one step (the other CAS)? Hi, If user1 in site1 with CAS1, mailbox is in Site2, then user1 will try to connect to CAS1 and CAS1 will proxy the request to CAS in Site2,CAS2 will return the user information with autodiscover urls, user get data via CAS2. So the commication between two site will cost the bandwith. Xiu

Both sites have internet connectivity, but since we have OWA/ActiveSync published through a reverse proxy (bluecoat at the moment, would like to replace this with an UAG), only one CAS is internet-facing. Can you internet face the other one was well? I guess not since you can only publish the OWA/ActiveSync to one CAS? Or, like mentioned before, you would need to load balance both? Hi, If you have UAG in each site, then you can have two site OWA published. So you may need to implement load balance for CAS server. CAS servers in serveral sites, then you can try to use hardware load balance. Xiu

Both sites have internet connectivity, but since we have OWA/ActiveSync published through a reverse proxy (bluecoat at the moment, would like to replace this with an UAG), only one CAS is internet-facing. Can you internet face the other one was well? I guess not since you can only publish the OWA/ActiveSync to one CAS? Or, like mentioned before, you would need to load balance both? Hi, If you have UAG in each site, then you can have two site OWA published. So you may need to implement load balance for CAS server. CAS servers in serveral sites, then you can try to use hardware load balance. Xiu How do you do this with only one URL?

Alright, I think I understand: The non internet facing CAS will be useless since it will not get proxied requests for the MBX server that is in its (physical) site, since the internet facing CAS can now serve those requests because there is only one site. Correct? So to make use of the second CAS, I would need to use software or hardware load balancing. (Or if it were to be Exchange 2010, a CAS array) If I were to only use one CAS that serves both MBX servers, how would that affect performance when it needs to get the data from the MBX server in the other physical site, over the 200 Mbit line? Is it comparable to when the request is proxied to the other CAS? Or faster, since it eleminates one step (the other CAS)? Hi, If user1 in site1 with CAS1, mailbox is in Site2, then user1 will try to connect to CAS1 and CAS1 will proxy the request to CAS in Site2,CAS2 will return the user information with autodiscover urls, user get data via CAS2. So the commication between two site will cost the bandwith. Xiu Aren't you again talking in Exchange 2010 terms? Internally, everyone connects directly to the MBX server with Outlook, since it is still Exchange 2007. See below drawing of the situation: At the moment, Site 1 and Site 2 are both seperate physical and AD sites. A request for a user with a mailbox on MBX2 in Site 2 will come in via the published OWA URL, which is pointing to CAS1, in Site 1. CAS1 will proxy the request to CAS2 which will fetch the data from MBX2, send it back to CAS2, which will send it back to CAS1, allowing the user to view his mailbox data. Correct? Now, if I change Site 1 & Site 2 into one big AD site (but still physically seperated), what will happen with the OWA request for a mailbox on MBX2? CAS1 will directly speak to MBX2 right? Eliminating the use of CAS2 in Site 2. Correct? Is the same the case for SMTP traffic? Both CAS1 & CAS2 are also HT servers. CAS1 is also the internet-facing HT server for incoming mail via SMTP. When mail is destined for Site 2, CAS1 (HT1) will forward the mail to CAS2 (HT2), which will deliver it to MBX2, right? If AD is one big site, will CAS1 directly speak to MBX2 with regards to delivering mail via SMTP?

Alright, I think I understand: The non internet facing CAS will be useless since it will not get proxied requests for the MBX server that is in its (physical) site, since the internet facing CAS can now serve those requests because there is only one site. Correct? So to make use of the second CAS, I would need to use software or hardware load balancing. (Or if it were to be Exchange 2010, a CAS array) If I were to only use one CAS that serves both MBX servers, how would that affect performance when it needs to get the data from the MBX server in the other physical site, over the 200 Mbit line? Is it comparable to when the request is proxied to the other CAS? Or faster, since it eleminates one step (the other CAS)? Hi, If user1 in site1 with CAS1, mailbox is in Site2, then user1 will try to connect to CAS1 and CAS1 will proxy the request to CAS in Site2,CAS2 will return the user information with autodiscover urls, user get data via CAS2. So the commication between two site will cost the bandwith. Xiu Aren't you again talking in Exchange 2010 terms? Internally, everyone connects directly to the MBX server with Outlook, since it is still Exchange 2007. See below drawing of the situation: At the moment, Site 1 and Site 2 are both seperate physical and AD sites. A request for a user with a mailbox on MBX2 in Site 2 will come in via the published OWA URL, which is pointing to CAS1, in Site 1. CAS1 will proxy the request to CAS2 which will fetch the data from MBX2, send it back to CAS2, which will send it back to CAS1, allowing the user to view his mailbox data. Correct? Now, if I change Site 1 & Site 2 into one big AD site (but still physically seperated), what will happen with the OWA request for a mailbox on MBX2? CAS1 will directly speak to MBX2 right? Eliminating the use of CAS2 in Site 2. Correct? Is the same the case for SMTP traffic? Both CAS1 & CAS2 are also HT servers. CAS1 is also the internet-facing HT server for incoming mail via SMTP. When mail is destined for Site 2, CAS1 (HT1) will forward the mail to CAS2 (HT2), which will deliver it to MBX2, right? If AD is one big site, will CAS1 directly speak to MBX2 with regards to delivering mail via SMTP? Hi, A request for a user with a mailbox on MBX2 in Site 2 will come in via the published OWA URL, which is pointing to CAS1, in Site 1. CAS1 will proxy the request to CAS2 which will fetch the data from MBX2, send it back to CAS2, which will send it back to CAS1, allowing the user to view his mailbox data. Correct? Yes. Now, if I change Site 1 & Site 2 into one big AD site (but still physically seperated), what will happen with the OWA request for a mailbox on MBX2? CAS1 will directly speak to MBX2 right? Eliminating the use of CAS2 in Site 2. Correct? Yes. Is the same the case for SMTP traffic? Both CAS1 & CAS2 are also HT servers. CAS1 is also the internet-facing HT server for incoming mail via SMTP. When mail is destined for Site 2, CAS1 (HT1) will forward the mail to CAS2 (HT2), which will deliver it to MBX2, right? Yes. If AD is one big site, will CAS1 directly speak to MBX2 with regards to delivering mail via SMTP? If you just publish CAS(Hubserver) to internet, that means configure your hub server to receive internet emails, than incoming mail folw(internet) will only use HUB1. Others like internal email flow, mail sending, HUB2 will bu used sometimes. Xiu

Alright, thx for your answers!