What does Microsoft 365 Informed Network Routing Do?

Smarts for Internal Networks, But Only with the Right Equipment

On November 30, Microsoft announced the general availability of Microsoft 365 informed network routing. Jeff Mealiffe, the Principal Architect for the feature, explained it as follows:

The informed network routing feature provides the ability for 3rd-party software defined wide-area network (SD-WAN) solutions to receive application-level feedback on network quality. We aggregate the feedback to individual network circuits which carry network traffic from your company locations to the Internet and on to Microsoft.

If you’re not a network administrator, this statement might not make much sense to you. I reached out to Jeff to learn more about the wonders of informed network routing and the practical difference this technology will make to Microsoft 365 tenants. Here’s what I learned.

No Change in Connections to Microsoft

The first thing to understand is that this has nothing to do with how Microsoft processes inbound traffic from customer tenants. The logic and principles developed since 2011 still apply: keep things simple and avoid passing the traffic through too many proxies. Once traffic hits a Microsoft connection point, it routes to the target datacenter and service very quickly. Any delay is typically in the flow from customer devices through the internal network (last mile) across the internet (middle mile) to Microsoft.

Checking Network Health

Inside a customer network, devices might test the connection to Microsoft 365 with HTTPS or Internet Control Message Protocol (ICMP) probes to measure if traffic reaches its intended destination in a timely manner. This approach works, but a generalized probe can’t determine how the traffic from individual clients flows when attempting to reach a specific service. In other words, you can get a yes or no signal that the Microsoft datacenter network is reachable, but you can’t tell if users are spluttering into their cornflakes because of jitter in a Teams video meeting or because the OneDrive sync client can’t connect to SharePoint Online.

The situation is further complicated when applications use different protocols to carry different traffic. Take that Teams meeting, which uses User Datagram Protocol (UDP) to make sure that its time-sensitive traffic reaches all participants. Most of the time, meetings flow smoothly, and everyone can see the video feeds for people and shared content. But if a carrier between the customer network and Microsoft decides to deprioritize UDP for some reason, suddenly video feeds might not be so good. Teams still connects and other traffic, like HTTPS-based messaging, works fine, but meeting participants might need to disconnect cameras to continue. And meantime, a standard probe reports that all is well with the connection.

Microsoft uses synthetic probes to measure and generate insights into network connectivity available in the Microsoft 365 admin center (Figure 1). Reviewing recent data for my tenant, I see that some of the connections I made from this week’s European Collaboration Summit in Dusseldorf show up. This probably reflects the relatively poor connectivity from large-scale Wi-Fi networks at such events.

Network insights in the Microsoft 365 admin center
Figure 1: Network insights in the Microsoft 365 admin center

Application-Specific Metrics

Replacing artificial probes with application-specific quality of service metrics to understand the quality of network connections to Microsoft 365 is the major benefit of informed network routing. Basically, network equipment like Cisco routers running IOS XE SD-WAN (see the documentation for details) can consume metrics generated by applications like Teams, Exchange Online, and SharePoint Online, to detect problems. The routers can then dynamically change the way traffic moves using other available links to improve the flow and make applications more responsive to users.

Microsoft also generates a per-link indicator for connectivity. The indicator simply reports if the link is OK, Degraded, or Bad in terms of its connection to Microsoft and comes from the telemetry generated by Microsoft 365 apps. Based on years of measurement, Microsoft knows what acceptable telemetry looks like in terms of criteria like latency, jitter, or dropped packets. By comparing the data for a link against what’s considered acceptable, informed network routing can notify network equipment when things are not as they should be.

Network Upgrade Required

If you’re a Cisco customer and have their SD-WAN gear deployed, Microsoft 365 informed network routing is a nice addition to the intelligence available for network management. Anyone else must wait for their network platform provider to upgrade their software to consume and response to the signals Microsoft makes available. And while you’re waiting for that to happen, take the time to review the latest guidance for Microsoft 365 networking. You never know, you might find something there that helps to improve connectivity without requiring any updates.

Keep up to date with developments like informed network routing by subscribing to the Office 365 for IT Pros eBook. Our monthly updates make sure that our subscribers understand the most important changes happening across Office 365.

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