• Communication with the cluster VIP from any computer on the same subnet is successful.
• Communication with the cluster VIP from any computer on a different subnet fails.
• If you apply the default gateway to the cluster NIC, everything works.

The problem? IP forwarding for any network interface on a Server 2008 box is disabled by default (as opposed to Server 2003 where forwarding was enabled by default). This leads to the behaviors exhibited above as any packet entering the inbound NIC (your NLB VIP address), has no way to exit the subnet and is subsequently dropped.

Fortunately for us, enabling IP forwarding on the cluster network interface is easy enough with a quick trip to the command line or registry (I prefer the command line/netsh route as a reboot is not required).

The following steps will enable IP forwarding on your cluster NIC:

NETSH

1. Determine the name of the clustered interface:

   netsh interface show int
   

2. Enable IP forwarding on the NIC:

   netsh interface ipv4 set interface "Clustered Interface" forwarding=enabled
   

3. Verify that forwarding has been enabled on the interface:

   netsh interface ipv4 show interface "Clustered Interface"
   

Registry

1. Add/Edit the following key:

   Key name: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
   Value Name: IpEnableRouter
   Data Type: REG_DWORD
   Value: 1
   

2. Reboot server.

Reference

• Dual-NIC NLB Configuration with Windows Server 2008 NLB Clusters

Without further ado:

1. Install the latest version of Desktop Manager (DM) that works with your operating system.
   • Verify that DM is connected to the BES.  If DM is not seeing your BES, your device will not reactivate after the OS upgrade is complete.
2. Install the 4.5 package.
3. Unplug your handheld from your PC and reboot.
   • A reboot was required in my case as DM and Windows did not detect the new device drivers for the handheld.
4. Plug your handheld into your PC.  Windows will automatically detect the updated device drivers.
5. Start your handheld upgrade from DM.
6. Wait.
7. Wait some more.
8. Did I mention you should still be waiting?
9. ??? Profit ???  Really RIM, does an upgrade need to take this long?
10. After the successful completion of your upgrade, DM will automatically reactivate your handheld with the BES.

Important notes:

• If you are connected to a Windows domain, when upgrading with DM, make sure you are signed in to your domain account that is tied to your handhelds email configuration.  If you do not do this, you will most likely not reactivate on the BES, and that is a BAD thing.
• If the upgrade does not take the first time, be sure you have rebooted and that you are utilizing the newest device drivers for your handheld.

Why would you want to upgrade and go through the pain?  For some of the following:

• BlackBerry Maps with Points of Interest
• Improved media player with playlist support and automatic playlist generation
• Voice note recording
• Video recording on Curve models
• Streaming support for YouTube and Sling Player
• Microsoft Office document editing with DocumentsToGo
• And more…