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CenterFuse Broadband Feasibility Report 26—50 Mbps 2 We can make the following observations about the upload speed tests: • This report discusses elsewhere what we're calling the upload crisis where slow upload speeds present a problem for adults or students trying to work from home, particularly when more than one person wants to work at the same time. 20% of Charter customers showed upload speeds under 10 Mbps. 71% of customers have upload speeds under 15 Mbps. • All households that subscribe to speeds of 100 Mbps or less have upload speeds of 21 Mbps or less. Customers subscribing to the 400 Mbps download product seem to be achieving upload speeds of around 23 Mbps. The two subscribers to 900 Mbps download products have upload speeds of 38 Mbps. The average latency on Charter was 20 milliseconds This is a reasonably low latency for the DOCSIS technology and indicates a network in overall good working order. This makes it even more of a mystery who so many customers have slow download speeds. The technology used in the last mile is generally the largest factor influencing latency. A few years ago, the FCC did a study of the various last mile technologies and measured the following ranges of performance of last-mile latency, measured in milliseconds: fiber(10-20 ms), coaxial cable (15-40 ms), and DSL (30-65 ms). These are measures of latency between a home and the first node in the ISP network. It is these latency differences that cause people to prefer fiber. The experience on a 50 Mbps fiber connection "feels" faster than the same speed on a DSL or cable network connection due to the reduced latency. There are a lot of underlying causes for delays that increase latency—the following are primary kinds of delays: • Transmission Delay. This is the time required to push packets out the door at the originating end of a transmission. This is mostly a function of the kind of router and software used at the originating server. This can also be influenced by packet length, and it generally takes longer to create long packets than it does to create multiple short ones. These delays are caused by the originator of an Internet transmission. • Processing Delay. This is the time required to process a packet header, check for bit-level errors and to figure out where the packet is to be sent. These delays are caused by the ISP of the originating party. There are additional processing delays along the way every time a transmission has to "hop"between ISPs or networks. • Propagation Delay. This delay is due to the distance a signal travels. It takes a lot longer for a signal to travel from Tokyo to Baltimore than it takes to travel from Washington DC to Baltimore. This is why speed tests are usually created to find a nearby router to ping so that they can eliminate latency due to distance. These delays are mostly a function of physics and the speed at which signals can be carried through cables. • Oueueing Delay. This measures the amount of time that a packet waits at the terminating end to be processed. This is a function of both the terminating ISP and also of the customer's computer and software. Total latency is the combination of all of these delays. You can see by looking at these causes that poor latency can be introduced at multiple points along an Internet transmission, from beginning to end. Page 31