ADDRESSING BANDWIDTH CONSTRAINTS IN THE HOSPITALITY AND SPECIALTY RETAIL INDUSTRIES

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Bruno Franklin
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1 ADDRESSING BANDWIDTH CONSTRAINTS IN THE HOSPITALITY AND SPECIALTY RETAIL INDUSTRIES Written By: Vic Herrera, Chief Technology Officer Bandwidth for remote viewing of surveillance data consists of several components. What most people frequently consider and understand relates to bandwidth quantity, i.e. how much bandwidth is available for uploads and downloads of data. In the following paper, we will discuss quantity but also address other elements that impact the user experience and, oftentimes, are the root cause of system performance issues. In addition to quantity, the elements of bandwidth that affect remote surveillance viewing include jitter, packet loss, and latency. In order to have a good viewing experience, these components need to be within reasonable tolerances. Traditionally, operators have used speed tests to check connectivity health. Most Internet speed tests are of marginal quality, at best, and only represent a slice in time. In order to diagnose remote viewing issues, operators need all the information above trended over time to get a more complete understanding of what is occurring. I will discuss how DTT monitors and trends this data later in this paper. First, I want to detail a few important points about video streaming. VIDEO STREAMING Video streaming is a serialized data sequence of time sensitive information. The best user experience occurs when a video stream flows smoothly and consistently over time. The optimal situation ensues with a clear, fast, network path between the server and client, or in DTT s case, between the user and DVR. Conversely, if there is a congested or slow network path between the two points, a user will detect a negative impact to the video stream. The aforementioned elements are what DTT uses to measure if the path is clear, fast, and consistent. JITTER Jitter is a variation in transmit times for the data a system is sending, or, in DTT s case, a video stream. Because DTT is handling a large stream of data, consistency is paramount. Please note the illustration below with appropriately applied ping times. In the first example, there are normal ping times, within one millisecond of each other. 1

2 In this next example, there are variations in ping times. The detected variance is outside required network specifications. This can be caused by congestion on a network or in the path between point A and point B. It is important to remember that the path between the viewer and the destination DVR has many intersections, or hops, any one of which can contribute to this issue. Note that DTT s jitter tolerance for video is about 23 milliseconds. Jitter has a stuttering effect that will cause the video to freeze or stop playing. It is similar to having a conversation with someone who is responding in incomplete sentences. In general, higher levels of jitter are more likely to occur on either slow or heavily congested links. Overall, jitter deals with the consistency or flow of data. Also, ping times reveal inconsistencies in packet flow, which is network jitter. PACKET LOSS Packet loss refers to data that doesn t make it from point A to point B. When this happens, the remote viewing computer experiences stutters and stoppage, and ultimately drops a connection. QUANTITY Entry level bandwidth offerings in DSL, cable modems, WiMax/LTE, and/or cellular technologies usually come asynchronously. That is with one speed faster or slower than the other. The larger number is always the download speed. For purposes of analysis, operators are interested in the upload number. This number is relevant to a user s remote viewing video experience. Higher grade, and consequently more expensive offerings like T1 s and Ethernet ports (typically fiber), tend to be synchronous at around 1.5 MB. On average, each camera needs 40KB of bandwidth. This number varies based on the amount of activity in the shot. Data traverses routers while moving from point A to point B. When operators troubleshoot, it is important to look at the data as it crosses hops. Herein, operators can see if there is latency, packet loss, or jitter. A recommended detection tool is Traceroute, which is used to document this network behavior. LATENCY Latency is the time it takes to get information from point to point. It is typically measured in milliseconds. Operators can use a couple different tools, such as Ping or Traceroute, to measure the time it takes to get information back from a location. Traceroute uses Ping to document time intervals but also includes all of the hops or intersections as data transverses many points even when traveling across a network. The examples below use Traceroute to give us a comprehensive overview of what is happening and where challenges may become evident. The Traceroute below goes from my home to my office. It traversed 14 intersections and the physical distance is about 5 miles. The box in yellow contains the ping times for each leg of the journey. Each leg gets tested 3 times and normally these numbers are in close tolerance, a few milliseconds of each other. Distance plays a part in this as well, particularly in distances over hundreds or thousands of miles. 2

3 Of particular interest are two issues, at hops 11 and 12. The stars indicate a dropped packet or no response. That means that the router at this intersection was unable to send back a response. The next hop, number 12, has a wide variation in the ping time, beyond 20 milliseconds. To illustrate the effects of distance on ping times, let s do a trace to Krasnoyarsk, Russia, approximately 6,000 miles away. You can see the Trans-Pacific jump at hop 9. Under optimum conditions, internet traffic travels cross country 2,400 miles in about 90 milliseconds. If we apply this to our trace above, which is 2.5x the distance and we multiply 90 x 2.5, we get 225ms. Given the fact that we are traversing a great distance, this trace and latency look good. Note the low quantity to get from point A to point B - two hops less than going to the office, just a few miles away. 3

4 Now let s review some examples of actual locations having network issues. The location detailed below is in Arizona, with a trace generated from Los Angeles. Notice the last hop highlighted. This is a great example of very high latency. These numbers should be less than 100 milliseconds. A significant challenge is noted here. This could be a problem with a network router, congestion caused by too many devices accessing the network, or potentially an issue with the server. With the trace generated, an operator has clearer direction about where to troubleshoot the network problem. 4

5 The next example shows wide variations in ping times associated with latency, lag and jitter, which results in a poor viewing experience as illustrated on hop 9 - variation of 50 milliseconds. 5

6 DTT S ROLE Now that I have detailed the components of bandwidth, let s discuss how DTT can monitor networks and ensure our customers get the best remote viewing experience. Bandwidth constraints have been an issue since the remote viewing of video surveillance data was introduced. The good news is that commercially available bandwidth quantity and quality continues to improve. When issues arise with remote viewing, DTT has found itself solving a challenge between the Internet Service Provider (ISP) and the user. The user wants to review remote video and the experience can be impaired due to the network issues associated with bandwidth. DTT will then work with the ISP to perform a quick speed test to ensure performance is meeting specifications. If the customer s experience is impaired, DTT will then show the ISP that an issue was detected. DTT has built testing tools that check and record the bandwidth quality on an hourly basis. DTT s onsite system uploads a small file once per hour, measuring the latency, jitter, throughput, and packet loss; and, records all of this data into a database. This data is then used by DTT support technicians to troubleshoot issues before they become a problem for users. This critical data removes the guess work and allows DTT to work with ISPs and resolve challenges when there is something occurring with the provider s service. In the green highlighted area below, note the amount of bandwidth needed to view 6 cameras within the MyDTT site; DTT s web-based enterprise portal. In the grey highlighted section, note the total amount of bandwidth needed to view all cameras in the location simultaneously. DTT has constructed a simple to interpret report on MyDTT that enables users to quickly review system bandwidth. In conclusion, the above explanation highlights elements of bandwidth that affect remote viewing. Quantity of bandwidth is of course very important but other elements also play a key role. After tens of thousands of installations, DTT understands better than any other surveillance vendor the elements needed for successful remote viewing and can ensure that they are up to par. 6

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