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How to setup multiple AD site test VM's to communicate without multiple NIC's or RRAS

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As Exchange technologies using multiple AD site infrastructures become more popular, Exchange PFE engineers have to build LAB’s spanning multiple AD sites using Virtual PC/ Virtual server or Hyper V.

I always used to use multiple NIC’s and Routing and remote access service (RRAS) to get communication working between machines in different AD sites. I used to spend time troubleshooting various routing issues because of this. Meanwhile, one of my colleagues in PFE, Ewan Mackellar suggested me the following workaround which serves as a really easy method to get multiples servers in different AD sites communicating without the need of having RRAS.

The basic idea is to trick AD sites and services to think that we are on different networks by manipulating subnet masks. Here’s the breakdown on how it works:

Take 2 sites within efourteen.com: UK and US

In the UK site, on the Windows 2003/2008 machine set the network card properties to the following:

Connection-specific DNS Suffix (UK) :

Description . . . . . . . . . . . : Intel(R) WiFi Link 5300 AGN

Physical Address. . . . . . . . . : 00-21-6A-55-FA-FC

IPv4 Address. . . . . . . . . . . : 192.168.0.3(Preferred)

Subnet Mask . . . . . . . . . . . : 255.255.0.0

DNS Servers . . . . . . . . . . . : 192.168.0.1

In the US site, on the Windows 2003/2008 machine set the network card properties to the following:

Connection-specific DNS Suffix (US) :

Description . . . . . . . . . . . : Intel(R) WiFi Link 5300 AGN

Physical Address. . . . . . . . . : 00-21-6A-53-DA-FA

IPv4 Address. . . . . . . . . . . : 192.168.1.3(Preferred)

Subnet Mask . . . . . . . . . . . : 255.255.0.0

DNS Servers . . . . . . . . . . . : 192.168.1.1

Both these machines will communicate since they are on a class B network. However, in AD sites and services, we need to create new subnets to indicate the 2 different sites:

image         image

We set Class C subnet here so that AD sites will think that these are separate networks. Now you will need to ensure that you have a site connector between UK and US.

In addition, if you want Intersite replication to occur more frequently than every 15 minutes, you must enable Change Notification on the Active Directory site link. How you do this depends on which OS is on your DC.

For Windows 2003 Domain Controllers:

•Open ADSIEdit.msc (in the Windows Support Tools) as a Domain Admin

•Open the Configuration naming context

•Navigate to Sites > Inter-Site Transports > IP

•Right-click the siteLink to modify in the results pane and click Properties

•Locate the options attribute and edit the value from to 1

•Click OK and repeat for other siteLinks, as necessary.

For Windows 2008 and Windows 2008 R2 Domain Controllers:

You can use the same method as Windows Server 2003 DCs or you can edit the values directly from AD Sites and Services, as follows.

•Locate the Site Link to modify in AD Sites and Services

•Right-click the Site Link and choose Properties

•Click the Attribute Editor tab

•Locate the options attribute and edit the value from to 1

•Click OK and repeat for other Site Links, as necessary.

Sunil Surendranath

Premier Field Engineer

Comments

  • Anonymous
    May 08, 2010
    Good to see this Sunil, I'm going to try this in my labs.