For those who already have a deployment of Live Communications Server 2005 SP1 and are looking to migrate to Office Communications Server 2007, the migration is straightforward. However, there are a few considerations to keep in mind:
The impact of migrating users from legacy presence to the enhanced presence model
Upgrading users' Communicator 2005 client to Communicator 2007
The possible need to decentralize your deployment to support users in remote offices to do Web conferencing and VoIP
In addition, you need to consider the following issues applicable to any Office Communications Server 2007 deployment:
Scalability considerations for the new modalities: audio, video, Web conferencing, and VoIP
The impact of the different modalities on your existing network and the user's experience of Web conferencing, audio and video quality.
Only considerations specific to migrating from Live Communications Server 2005 to Office Communications Server 2007 will be covered in this section. With Office Communications Server 2007, a new presence model is introduced to overcome the shortcomings of the presence model defined in Live Communications Server 2005. Mainly, the Office Communications Server 2007 presence model addresses the issue of large Session Description Protocol (SDP) presence documents sent across the network by shredding this presence document into discrete XML sub-documents. This way a change made, for example, to the Notes field by the user won't result in resending the entire presence document to the home server, as was the case with Live Communications Server 2005. With Office Communications Server 2007, only the sub-document where the Notes field was defined is transmitted to the home server in an SDP envelope. This approach results in a more efficient use of the network as well as resources on the home server. The home server needs to parse only the sub-document instead of the entire presence document.
Another driving factor in changing the presence model in Office Communications Server 2007 is the customers needing to offer a more granular permissions model than the permission model supported in Live Communications Server 2005, which is limited to Allow and Block. Users want more granularities, and they want to be able to assign varying levels of permissions to contacts. For example, a user might not want to be interrupted during a meeting except by the boss or a particular family member.
The recommended way to upgrade to Office Communications Server 2007 is to perform a side-by-side migration. That is, install a second server installation running Office Communications Server 2007 in the same forest as your Live Communications Server 2005 deployment and migrate the users. The impact on hardware from deploying a second Enterprise Edition pool is significant, because doing this requires duplicating the number of physical servers—one set for Live Communications Server 2005 and another set for Office Communications Server 2007. To minimize this impact, you can deploy the Office Communications Server 2007 Enterprise Edition pool with the minimal set of hardware required—one back-end server and one front-end server. As you migrate users from your Live Communications Server 2005 Enterprise Edition pool to the Office Communications Server 2007 Enterprise Edition pool, you can start decommissioning front-end servers from the Live Communications Server 2005 Enterprise Edition pool and reusing them as front-end servers for the Office Communications Server 2007 Enterprise Edition pool.
Moving users homed on Live Communications Server 2005 to Office Communications Server 2007 can simply be done via the bulk Move Users Wizard. This wizard is accessible from the Admin Tools MMC and the DSA.MSC MMC. If you are using the Admin Tools MMC, the Office Communications Server 2007 version must be used. Select all the users to be moved, right-click, and select the Move Users Wizard as shown in Figure 15-6. If the move process fails, it's likely that either the source server (Live Communications Server 2005) or the destination server (Office Communications Server 2007) is offline and not operational. Verify the service is functioning correctly before attempting the move user process again.
Users moved to an Office Communications Server 2007 Standard Edition Server or Enterprise Edition pool from Live Communications Server 2005 are not automatically enabled for enhanced presence. They remain in legacy mode until the administrator explicitly enables them. Because users enabled for enhanced presence cannot be returned to legacy presence, the administrator can control the timing for when to enable this feature. Enhanced presence can be enabled from the user's Properties page by clicking the Configure button, which displays the User Options screen (shown in Figure 15-7). To enable users in bulk for enhanced presence, the Configure Users Wizard is an easier choice (shown in Figure 15-8).
The process of migrating users from Live Communications Server 2005 to Office Communications Server 2007 is now complete. You can enable those users for new functionality only available in Office Communications Server 2007, such as UC and Meeting features.