Intersite Directory Replication via the Internet in MS Exchange 5.5

by Lee Derbyshire [Published on 16 May 2002 / Last Updated on 16 May 2002]

MS Exchange provides a method, known as Directory Replication, of combining the email directories from a number of sites so that they can function as one.

Introduction

In today's business environment the Exchange administrator is quite accustomed to dealing with changes in company organization. It is now quite common to be required to integrate an email system with others in one or more remote locations, often in different countries. MS Exchange provides a method, known as Directory Replication, of combining the email directories from a number of sites so that they can function as one. This means that all email destined for a geographically disparate Organization can be routed from the Internet to a single server. It also facilitates the sharing of documents, in Public Folders, so that they are more easily available to users at any of the connected Sites.

There are, as in most things in computing, several ways of doing this. The method described in this article uses the MS Exchange Internet Mail Service Connector, more usually referred to, for reasons of brevity, as the IMC or IMS.

Procedure

Now, when you're dealing with computers there is always a catch. In the case of Directory Replication the catch is that, as previously mentioned, you can only do it if your Sites have the same Organization name. As catches go, it has to be said that this is right up there with the best of them, and if you are intending to connect to the Site of a recently acquired company you can guarantee that they will have a different Organization name. Since the Exchange Organization name is defined at Setup time it cannot routinely be changed. If you find yourself in this situation, you will need to find out about the MS Move Server Wizard utility and come back at a later date.

Okay, so you have two MS Exchange 5.5 servers that have the same Exchange Organization name, connected only by the Internet. I'll also assume that both have a working IMC.

Before you begin, there is a certain amount of information that you will need which I have summarized below in table 1. The values given here are for illustration only and you will, of course, need to supply real values that are relevant to your Exchange Organization. Besides, regular readers of TCP/IP Weekly will notice that these IP addresses are in private address space and are not Internet-routable.


   Site Name   Email Domain   Server Name   IP Address 
 Local Site   SITE-1   ORG-1-SITE-1.com   SRVR-1   192.168.1.1 
 Remote Site   SITE-2   ORG-1-SITE-2.com   SRVR-2   192.168.2.1 
Table 1.


You will also need to consider the possibility of any duplicated Display Names once the Directories have been combined. The most obvious one is the Administrator account. MS Exchange can cope quite happily with the existence of two similarly named accounts because although they may look the same, the Directory Names  will be quite different. To save yourself some confusion, though, you should rename them so that you can tell the difference. Something like 'Administrator (SITE-1)' should suffice.


This procedure will need to be performed twice; once at the local Site, and again at the remote Site. First, start the Exchange Admin. program and expand the Directory tree in the left-hand window until you can see the Connections container. Click on the Connections container.



Fig. 1 - The IMC in the Connections container.



Assuming that you have a working IMC, it will be displayed in the right hand window as shown in figure 1. If you do not see an IMC listed, then you will need to either add and configure one, or use another method to connect your sites. Double-click the IMC to open its property pages and then head for the 'Connected Sites' property page which is shown in figure 2.



Fig. 2 - The Connected Sites property page of the IMC.



Click the button labelled 'New...' to show the Site properties dialog box as shown in figure 3. Enter the details of the remote Site. Your Organization name will already have been entered into the dialog box, and should not be changed, but you do need to enter the name of the remote Site. In my example, the remote Site is called 'SITE-2' .



Fig. 3 - The General properties of the new Site.



Click on the 'Routing Address' tab to show the dialog box shown in figure 4. Enter 'SMTP' as the Address Type and enter the Email Domain name of the Site you are connecting to in the field labelled 'Address'. In my example, the remote Site's Email Domain is ORG-1-SITE-2.com.



Fig. 4 - The Routing properties of the new Site.



Click 'OK' to close the Site Properties dialog box. The new Site should now be listed on the IMC Connected Sites property page as shown in figure 5.



Fig. 5 - The new Site listed in the IMC.



Click on the 'Connections' tab of the IMC properties to reveal the property page shown in figure 6.



Fig. 6 - The Connections property page of the IMC.



Click on the button labelled 'E-mail Domain...' to reveal the Email Domains dialog box shown in figure 7.



Fig. 7 - The Email Domains property page of the IMC.



Click the button labelled 'Add ...' to reveal the Add E-mail Domain dialog box shown in figure 8. Enter the E-mail Domain name of the remote Site, click the radio button labelled 'Forward all messages for this domain to host:' and enter the IP address of the Exchange Server in the remote Site in the field below.



Fig. 8 - The properties page of the new Email Domain.



Click OK to close the Add Email Domain dialog box. You should see the remote Site's Email Domain name listed in the property page as shown in figure 9.



Fig. 9 - The new Email Domain listed in the IMC.



Click 'OK' to close the Email Domain property pages, and then click 'OK' on the main IMC property pages to save all the changes that you have just made. You will need to stop and then restart the IMC using the Services applet in the Windows NT Control Panel to make the changes take effect.



Fig. 10 - The restart warning message box.



OK, so you've restarted your IMC. Now you need to add a Directory Replication connector and your configuration is complete. Click on the Directory Replication container in the left-hand pane of the Exchange Admin program and from the menu, select File -> New Other -> Directory Replication Connector... . You should see the dialog box shown in figure 11. Type in the name of the remote Exchange server and select the radio button next to the caption 'No, the remote site is not available on this network.' Click OK.



Fig. 11 - The New Directory Replication Connector dialog box.



You should now see the Directory Replication Connector property pages. Click on the tab labelled 'Schedule' to reveal the property page shown in figure 12. Select the radio button next to the caption 'Always' to force replication every fifteen minutes. Lastly, click OK to close the Directory Connector property pages.



Fig. 12 - The Schedule property page of the Directory Replication Connector.



Within a few minutes, you should be rewarded with the appearance of a new icon representing the the remote Site in the Directory pane of the Exchange Admin program, as shown in figure 13. You should not, however expect see any Site details until the remote site has also been configured.



Fig. 13 - The remote Site listed in the Exchange Directory.



Now, you need to go to the server at the remote Site and configure it in the same way, except that the remote server needs to be supplied with the Site name, Email Domain name, Server name and IP address of SITE-1. There should be a furious exchange of email messages between the two Sites and if everything has been configured correctly, the Directory Tree details should become fully populated.


If you want to share documents between the two Sites, you can do this by creating Public Folders in MS Outlook, and configuring replicas of the Folders (and the required permissions) in the Exchange Admin. program. Any documents placed in these Folders at either Site will be replicated to the other Site and users at either Site can modify them if the permissions have been so defined. However, since replication occurs every fifteen minutes there will be a propagation delay. You may be asking what happens if two people are working on the same document at the same time? The simple answer is that the most recently changed document will be the one that survives.


All you need to do now is make sure that you have a good backup strategy for your MS Exchange Public Information Store.

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