Experience Exchange Sever

April 8, 2017

Case study for Office 365 migration – Part 1

Filed under: Office 365 — vijayarelangovan @ 8:27 pm

Recently i worked on Exchange 2010 to Office 365 migration.  It is a complex environment, i had to customize too many things to be able to make this successful.  This post is to explain the challenges that i have faced and how i was able to get around the situation.  I’m not covering technical details of the migration process, but it is just a case study.

First let me tell you the existing architecture,

  • Parent company – ABC.COM
  • Child Company – XYZ.COM
  • Child domain of the child company is – UK.XYZ.COM (this is domain were Exchange environment is present)

The oragnization decision is to bring all the employees under one roof.  Atleast for now, to bring email systems to parent domain.

Existing setup is

architecture copy

  • Each users from UK.XYZ.COM have a separate AD account to access the ABC.COM resources.
  • Each users from UK.XYZ.COM are mapped to the corresponding AD account on ABC.COM
  • The password of UK.XYZ.COM users account and their corresponding AD account on the ABC.COM are sycned using Dell password sync.
  • Each users from ABC.COM have a mailbox on UK.XYZ.COM, and the email are forwarded to ABC.COM mailbox if any emails are sent.
  • If there is any email for UK.XYZ.COM coming in ABC.COM, it will be routed through the AD accounts created on ABC.COM

So, the environment is so complicated, and the job is to bring everyone under one roof when migrated to office 365.

I’m not going to explain technical details, rather I’m going to explain the challenges and how we overcome all that.

For any given architecture i feel that following should be the prime focus of an Architect,

  • Defining a Model like
    • Type of licensing
    • Identity management
  • Active Directory consideration
    • UPN identification
    • Domain trust consideration
    • attribute consideration and remediaton
    • Identification of OU to be synched
  • Exchange server consideration
    • Mailflow
    • Email domains
    • Autodicover & Exchange web services
    • Exchange certificate
    • Active sync solution/MDM
    • Message limits
    • Mailbox sizing
    • Public folder
    • Archiving and Journaling
    • SMTP relay setup
    • Third party integration
  • Network Consideration
    • Bandwidth & Utilization
    • DNS requirement
    • Internet proxies
    • Firewall ports consideration
  • End-user desktop considerations, like windows version, outlook version, anti-virus
  • Future expansion consideration

Out of the above said considerations, the challenges that needs to be addressed or discussed

Mailflow – Right now, there are 2 incoming gateway.  one for ABC.COM and one for XYZ.COM.  When we implement office 365, how this is going to affect.  How many hops an email had to travel?, How to address the email loop? and so on

Dirsync – Right the password is synced from XYZ.COM to ABC.COM DC’s through Dell password sync.  After Office 365 who is will be the authority for syching the password.  Is is ABC.COM only or Both ABC.COM and XYZ.COM? if it is single authority, then which domain should own it?

Domain name – Fortunately, both domain has a common name, @domain.com.  Can we use the same name for the user to authenticate themselves to Office 365? if they use the same @domain name, if so, how this can be federated for 2 domains?

Domain Trust – There is one way trust between XYZ.COM to ABC.COM.  Though the trust between 2 root domains are transitive, does that going to impact UPN?,

Auto-discover – Since both the domain have the same common name, after migration, how the users from each domain will reach Office365 mailbox from inside the network? External URL needs changes? or Outlook on the client machine needs to be upgraded (User have office 2010)

MDM – Users in both the domain users same MDM solution (mobile iron) but different infrastructure.  Does that need to be changed? or both the infrastructure should be integrated or redefine a new solution?

In my Part 2 post ill explain how to overcome this challenge and the resulting architecture

VJ

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