All packets are equal.. But some are more equal than others

Any network engineer will tell you that in order to ensure delivery of critical application data, you need QoS. We can essentially create fast paths through the network for certain types of traffic,  engineering our network to be predictable even though we can’t necessarily predict the traffic patterns. The problem here is it generally forces us to allocate bandwidth capacity to certain types of traffic even when they are not there, so lower priority traffic cannot utilize all of the bandwidth efficiently in the absence of critical data. Think of it as the unused HOV lane, or the security line at the airport only for the exclusive use of the million milers … (yep that’s me in that line)

Now an alternative approach would be a dynamic model whereby critical application data gets allocated bandwidth on demand as it appears In the network, and also gets delivered to the best path through the network. Now we can allow less important data to consume most of our good bandwidth whilst there isn’t a critical application flow, but as soon as one appears, we shape the lower data away from our best path to deliver the more important data. “Impossible” I hear you say! Wel, no, not really. Isn’t that what QoS does? If a packet marked EF arrives at the same time as one that’s not marked, a router will forward the EF one first. The thing that is lacking in traditional networking terms is the ability to do this network wide on the fly. It requires more intelligence than an individual router in the network can have. You need a network wide awareness of what is happening and intelligence and control at the edge to be able to adjust very very quickly to meet the demands of the applications.

Now if we can do that (and yes we actually can), we can begin the question the need for QoS in the cloud. If we don’t need QoS then we can now look at WAN networks that don’t have QoS as viable for enterprise quality traffic, without the penalty of poor application performance.

Categories: Software Defined WAN (SD-WAN)


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