Exchange Server 2010 and UDP Support

Computer Network

In his blog, UDP Notification Support Re-added to Exchange 2010, Kevin Allison announced that Microsoft is now going to include User Datagram Protocol (UDP) notification functionality support with Microsoft Exchange Server 2010.

When Exchange Server 2010 was originally released, back in 2009, it did not include support for UDP for new mail notifications. Exchange Server 2010 UDP notification support should be available in Exchange 2010 SP1 Update Rollup 3 (SP1 RU3), scheduled for March 2011. The RU3 schedule has been adjusted in order for the engineering team to complete the requisite work to include UDP support within the rollup.

Previously, whenever Outlook 2003 displayed new messages, or needed to display changes to folders, it was expecting to use UDP for those notifications. Because of the UDP change those updates would take much longer than expected. The send/receive process was also affected and would take more time than it did before with prior releases of Exchange Server. Specifically, folders would take a long time to update when an Exchange Server 2010 user used an Outlook 2003 client in online mode.

This problem affected Outlook 2003 because it used UDP as its primary method for receiving notifications from an Exchange server. Outlook 2007 was mostly unaffected by this problem because, by default, it used an asynchronous notification method that did not rely on UDP notifications.

Adding UDP back into Exchange Server has been welcomed by many in the administrator and user community. Without the UDP functionality being added some customers were facing having to upgrade all their client versions. This would have meant much time used for what is now an unnecessary project. More time can now be spent on improvements and enhancements rather than on corrections and fixes that would have been spent on client upgrades. In addition, many administrators and IT departments were delaying the rollout of Exchange Server 2010 to avoid having to deal with the performance issues and the expected blowback from their user community.

The Update Rollup 3 for Exchange Server 2010 SP1 (KB2492690) also contains a number of other fixes that were reported by customers reported. It also includes fixes for internally found issues since the release of Rollup 2. Highlighted fixes include the following:

  • ‘Database Copies’ list is being populated incorrectly (case sensitive) in EMC with DAG in place after upgrade to E14 SP1
  • Users without mailbox can’t delete items in shared mailbox via OWA premium
  • Folders take a long time to update when an Exchange Server 2010 user uses Outlook 2003 in online mode

Update Rollup 3 for Microsoft Exchange Server 2010, Release to Manufacturing (RTM), has been made available.

The recommended order of updates for your Exchange servers is:

  1. Internet-facing Client Access servers
  2. Other Client Access servers
  3. Hub Transport servers
  4. Mailbox servers
  5. Edge Transport and Unified Messaging servers

Once the update rollup 3 has been applied to the Exchange 2010 SP1 client access servers, administrators should also configure the servers to support UDP based push notifications. UDP based push notifications is the most ideal method for Outlook 2003 clients to receive notifications from an Exchange server. The benefit is that users will see a performance increase when using online mode for their email communications. UDP push notifications can be enabled by creating a new DWORD registry key named “EnablePushNotifications”.

After an administrator installs the update, they should create the following registry subkey to enable the UDP notifications support feature:
Subkey location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeRPC\ParametersSystem
Subkey name: EnablePushNotifications
Type: REG_DWORD
Value: 1           <———-this will enable push notifications.

After enabling push notifications the Exchange 2010 Client Access Server (CAS) should be restarted.

When UDP push notifications have been enabled, the Outlook 2003 clients will connect to the Exchange 2010 CAS servers using TCP. Once logged on, the port number and IP address that the Outlook clients expect to receive push notifications on are communicated to the CAS server. By default, the RPC Client Access service on an Exchange 2010 Client Access server uses the TCP End Point Mapper port (TCP/135). For outgoing connections, every time an Outlook client connects to Exchange server, an RPC port number in the dynamic RPC port range from 6005 to 59530 will be used.

Additionally, enabling push notifications on the CAS servers will result in something similar to frame number 440 being displayed by the Microsoft Network Monitor (NetMon) whenever a UDP based push notification is sent from the CAS server to an Outlook 2003 client.

Written by Mike Rede

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