Azure Express Route and QOS – Careful Now

The benefits of Express route are well documented, and from the horses mouth, “ExpressRoute connections offer higher security, reliability, and speeds, with lower and consistent latencies than typical connections over the Internet”. A point of contention has been this so called reliability.

The only way to guarantee reliability in packet switched networks is QOS. Sure, through capacity management and or ‘massive pipes’ this can be avoided to a certain extent, but there is always a risk that one device/user/application could consume all of that bandwidth leaving other systems with a smaller piece of the pie.

We have recently adopted Skype for Business PSTN Calling and through this have developed a need for a priority queue on EF (voice traffic effectively) marked packets. Microsoft’s documentation is quite clear on how it thinks QOS should be deployed.

It needs to be deployed end-to-end.

A QoS capable connection must be configured end-to-end (PC, network switches and routers to the cloud) as any part in the path that fails to support QoS could degrade the quality of the entire call

Your express route provider must provide a class of service for EF packets.

Each ExpressRoute network service provider will have a class of service (QoS) that is appropriate for real-time voice and video. This COS is called ‘Expedited Forwarding’ (EF) for voice and ‘Assured Forwarding’ (AF) for video

The problem is that our network provider and Microsoft doesn’t mandate this requirement despite it’s clear stance on it. I’ve labored through support tickets both with our provider and Microsoft – The provider has no interest as there is no pressure (from Microsoft, or other customers at this point) and Microsoft won’t force them to implement it.

The post serves little more purpose than to say, ‘be careful’ when expecting your express route provider to support QOS. They may not, and they are not required to.

We are looking at alternative network providers.

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