The Internet is Not a Pipe and Bandwidth is Bad
Neil Davies, Co-Founder, Predictable Network Solutions
Date: Wednesday, June 29
Time: 9:00 - 9:30 AM
Location: Salon E
Category: Technology & Engineering
Neil will present a significant advance in applied mathematics and its application to queuing algorithms and packet scheduling. He will describe a new way for understanding packet flows and their statistical properties. It allows networks to be run at full capacity, and the budget of loss and delay to be dynamically assigned to packet flows. Each packet flow can be given a statistically assured quality of delivery. This can be achieved at a fraction of the cost and complexity of today's circuit-based paradigm for managing "bandwidth" - a concept that is fatally flawed.
From the dawn of the telephony era, communications service providers have been selling circuits as their primary product. Even today, we buy packet-based connectivity using a circuit metaphor of "pipes" with "bandwidth". We use a variety of techniques like MPLS and VLANS to sub-divide physical carrying capacity by quantity and quality -- creating "virtual pipes".
Within each (virtual) pipe, we effectively treat all traffic as being a first-class passenger, whether that treatment is appropriate or not. Our naive approach to QoS is to always create more pipes carrying first-class traffic.
If we ran physical trucks like we run networks, we'd carry gravel in refrigerated containers, because that's what fresh tomatoes need. We would manage QoS by reserving lanes on motorways for different types of freight. The only answer to lack of capacity, or tomatoes perishing in transit as they get stuck behind gravel trucks, would be to build more roads. Freight carriers would be bankrupted by waste, and infrastructure providers overwhelmed by the cost of inefficient resource utilisation.
The underlying problem is that we continue to propagate circuit thinking onto packet networks where it is not appropriate. This approach causes two problems. Firstly it leaves us with networks that are nearly empty (to preserve "quality"), such as for emulating circuit telephony over IP. Secondly, networks fail to deliver the appropriate value to the user (to utilise "quantity"), as many Skype users will attest when a video call breaks up. The result is an industry and ecosystem that is out of balance, since the current mental models we employ do not match the reality of the networks we have built.
The question is how to match supply and demand better, not just over the next microsecond, but over the next month. The answer is to understand that the Internet is not a grid of pipes moving information indiscriminately, it is a method of focused delivery of that information.
It is the properties of that delivery, not the information itself that are the primary driver for good quality user experience. Communications service providers need to become data logistics providers. Think of it as the difference between a shipping line and FedEx. FedEx doesn't sell portions of ships, it sells promises of delivery.
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