If you believe that QoS is “standard” – you should read on – because although you are technically “right,” you are fundamentally wrong.
So, let’s start with what IS “standard” about QoS and that is “tagging.” By tagging, we mean bits that are set in a frame or packet header that indicates what level of priority that a session is requesting. It is only a request – something like writing “urgent” on a package. It is only an indicator of the processing that you want, not what you will get.
At Layer 2, the IEEE 802.1p standard defines priority bits – usually referred to as “p-bits.” At Layer 3, the less-simply-named “differentiated services code points” or DSCP do the same thing.
But, that is where the standards end. There is no standard for implementing the queues and other traffic management logic that make up the core of any QoS solution. All QoS solutions are the same in that they all will use some form of queuing but differ in how many queues are used (often up to eight) and how they are managed.
The only way that you can determine how an SD-WAN solution will handle YOUR traffic is to benchmark it – to test it.
Unfortunately, there are no test tools that will magically do this testing for you. You will need to understand the nature of your traffic and craft a microcosm of that traffic to run through the SD-WAN to determine just how the QoS mechanism will handle your traffic.
The Tolly Group SD-WAN Benchmarking Best Practices for QoS report will help you in your efforts.