Office 365: How to Calculate Bandwidth Requirements When Moving From MPLS to SD-WAN or SASE

Office 365 & Teams

How much bandwidth should you budget for each site when deploying Microsoft Office 365? It’s a common question, one posed to me yet again by one recent customer. 

They were a global MPLS shop with 40 locations worldwide. The company was planning to transition to SD-WAN and local Internet breakout. They had been storing their files on local servers and, in other cases, going across the reliable MPLS network to the remote servers. Now they were looking to replace all of that and ditch the server for Office 365 and MPLS for SD-WAN. 

The Capacity and Uptime Challenges 

The transition poses two main challenges —  capacity planning and uptime. The uptime challenge was perhaps the easiest to address. For that, we connected sites with dual, diversely routed Internet connections and used the SD-WAN device to load balance between them. In even more serious cases, we added a wireless connection. Together, we’ve seen uptime levels hit not five 9s but six 9s of reliability. 

But capacity planning was more challenging. Unfortunately, there’s no simple answer as to how much capacity Office 365 will use. Despite the single name, Office 365 is a brand for a suite of applications. Depending on which of those applications you choose to roll out and your users’ usage will significantly impact the required capacity at a given site. 

Suppose, for example, you have 240 users —  half of them are “Heavy Users” of Office 365 and the other half are “Medium Users.” We’ll assume Heavy Users require 3.66 Kbps peak capacity per user; Medium Users consume 2.11 Kbps peak capacity apiece. And OneDrive? It’ll consume 300 Kbps per user. (Bear with me, there’s a method to my madness.)

What you find is that overall, the site will require nearly 80 Mbps of capacity (79.2 Mbps to be exact) for Office 365 alone. OneDrive is by the biggest user of bandwidth at 72 Mbps. No surprise there as OneDrive is constantly replicating traffic up to the cloud. Teams Video with its use of video conferencing is at 4.2 Mbps, and Teams Voice is at 1.92 Mbps (see chart). Point is, change the profile of your users or drop any one of those applications, and capacity requirements will change substantially. 

The Office 365 Calculator

How do I know all of this? Where are the specific numbers coming from? Not from any third-party utility that I could find. Currently, Microsoft does not provide an effective way to estimate bandwidth requirements There are all sorts of tools available, sure, but not ones that will estimate bandwidth consumption.  You can also do the math yourself but that requires balancing some 14 different variables, such as SharePoint Interaction Size, SharePoint User Transactions/Hour, amount of capacity consumed by Team Voice and Team Video, and more.

These numbers come from an Office 365 bandwidth calculator we built to address this very problem. It’s based on research done for numerous clients interested in adopting Office 365. We’ve found it to be quite accurate in predicting their requirements.  

Yes, the variables are quite specific. Getting at the information will require working with your O365 administrator. Some of the data, which can be found in the Admin panel. 

Or reach out to us. SD-WAN Experts offers a free, no-obligation WAN Jumpstart Kit for that very reason.  You’ll get a free SD-WAN assessment, guidance on SD-WAN and Office 365 deployment at no charge or obligation to engage with us. 

What do you have to lose? 

Click here for more information. 

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