Office 365 Series: Deployment Strategies

Posted by Charley Lingerfelt

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8/1/14 8:00 AM

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There are three major kinds of deployment and integration approaches when it comes to Office 365. We've seen the number of users and mailbox size are the primary drivers to determine which deployment strategy to use.




1. Big Bang Migration, Standalone Authentication, and User Managed Migration

The term Big Bang Migration is used to describe a tactical migration of users, email, and file content to Office 365 where the data and user size is relatively small. The cutover would likely be accomplished over a weekend, to minimize the business disruption.

Standalone Authentication simply means that “single sign-on” will not be implemented to tie your Active Directory login to the Microsoft Office 365 login your employees will use.

User Managed Migration means that the project manager for the Office 365 deployment project will ensure all user accounts with their associated contact info are created in Office 365 and that instructions are provided to each user to move their email and their file content. A project timeline is provided to users to let them know when their tasks must be accomplished and at the time when email and file content migration is complete, DNS changes will be implemented to point incoming email to the Office 365 Email Services.

Variations to this plan include only performing the File Migration work to SharePoint Online during the week and then performing the email work over a different week/weekend.

Link to Office 365 Identity Management Poster

2. Big Bang Migration, Active Directory Integrated Authentication, and Centrally Managed Migration

The shorter migration size and time is assumed in this scenario, so the Big Bang Migration can be used in this strategy.

Active Director Integrated Authentication (ADFS) can be created and managed in one of two distinct technologies / processes: DirSync and Active Directory Federation.

DirSync does what its name implies. It synchronizes your Office 365 Identity with on-premise Active Directory System. DirSync synchronizes your usernames, passwords and other attributes on a default schedule every 3 hours.

ADFS is a little more complicated to setup, but you get more simplicity for users.

  1. Single Sign-on is present. Users login to their personal computer through Active Director and their credentials are cached so they don’t have to login to SharePoint, Outlook and Lync separately each time.
  2. Password policies are kept on-premise and managed by IT Administrators.

For more details on the differences between Directory Synchronization and Federation, ZDNet published this.

For more information on ADFS, Microsoft has more details.

In a centrally managed migration of email, the project team will be migrating all email. This is certainly easier on the end-users, but impact to the project team to perform the actual migration is higher. Often 3rd party tools are used to help reduce this burden.

3. Co-existence, Active Directory Integrated Authentication and Centrally Managed Migration

ADFS and Centrally Managed Migration tasks are the same as deployment strategy #2 in this scenario.

Co-existence is the functionality that provides larger organizations to pass email between on-premise email systems and Office 365 Exchange Online without having to perform a “big bang” cutover. This allows organizations to migrate to Office 365 over months and even years based on the number and size of mailboxes. As users are migrated, their email address stays the same but the email is routed to where it lives without the need to modify user behavior.

Other Notes

An often overlooked aspect of these migrations is the Internet Network Bandwidth. I highly recommend that customers assess their current bandwidth needs, how much bandwidth is necessary for the migration and then how much bandwidth will be necessary moving forward after the migration is complete. Overlooking this risk could cause the migration project to run much longer than anticipated. 


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Topics: Microsoft