• Bandwidth Values
• A Practical Example of Bandwidth Use
NHWC administrators and leaders often ask “How much bandwidth does NHWC use?” Unfortunately, there is no single answer. Bandwidth can be measured in different ways, and NHWC’s bandwidth use depends upon how you use NHWC. In general, when two or more users are in an NHWC session, they use a certain amount of bandwidth to connect to the server and send data back and forth. You must ensure that your users have enough bandwidth to participate in class. You can do so by understanding how NHWC uses bandwidth, and determining how much bandwidth is available on your network for NHWC traffic. This appendix document provides a practical example to help you understand bandwidth use in an NHWC session.
What Is Bandwidth?
Bandwidth is a measure of the amount of data transmitted or received per unit of time, usually measured in seconds. Bandwidth is proportional to the complexity of the data that is being
transmitted. For example, it takes more bandwidth to download a photograph in one second than it takes to download a page of text in one second. Large sound or video files require even more bandwidth to download.
The bandwidth utilized by NHWC in any NHWC session fluctuates depending on what is occurring in the session at that time. The purpose of this document is to outline how each of the relevant tools behaves, and the available throttles that can be used to both set defaults and cap the amount of bandwidth used by those tools.
In all of the features listed below, you will see that NHWC has been designed to be bandwidth conservative.
The numbers referenced within this document are all in the context of bandwidth required at the NHWC server, or if all network traffic is being funneled through one single point. Charts are included with anticipated bandwidth usage, for varying content and presentation tools, with different numbers of users in an NHWC session at the time.
Throughout this document we will reference screenshots captured from an NHWC server’s performance monitor to illustrate several points. Please note, these images reflect a controlled environment with only one active session occurring.
In the typical business day many meetings are scheduled at different times, while others may overlap, or are scheduled for the exact same time. This ebb and flow of traffic across multiple sessions sometimes coincides, resulting in higher bandwidth usage across a network, or upon the NHWC server than what is occurring in a single session but more often averages out close to or below that.
Another way to approach this explanation is to consider that the bandwidth behavior of one NHWC session with 1,000 people in it, walking through a presentation simultaneously, is very different from the bandwidth that would be used in 50 sessions with 20 users in each, with separate agendas and timelines, even though the same numbers of licenses are being used.
Joining an NHWC session / Downloading the NHWC Client
Before looking at the following presentation tools, let’s consider the number of people joining an NHWC session. Each individual will receive the NHWC client as a download, either at the time the session is scheduled to start, or when performing a system test ahead of time.
Mitel NetSolutions Hosted Web Conferencing User Guide 176 | P a g e The 9 NHWC client is compressed during download to approximately 5.0 MB in size. Each user will download that file the first time they join an NHWC session. On subsequent “joins” they will need to only download a session configuration file, often referred to within our product as the LRN, which is approximately 10kb in size. Downloading these files is done through a browser, and is handled by a standard http(s) request. As with all standard http(s) requests, the internet browser will utilize any and all bandwidth available to it until the entire file has been retrieved.
Another way to think about this is that if 10 people are joining an NHWC session for the first time at 4pm, collectively they will all download about 50MB, which will get the NHWC client to each of them. The following graph illustrates several users in a session, with the large blue spike being several additional users, downloading the client and joining the session already in progress.
There are several options to rollout or distribute the NHWC client across a network, separate from the joining process, to minimize network impact when a large session is anticipated to occur. First and foremost is the NHWC system test, included by default in every invitation and NHWC website, prompting the user to test their system 24 hours in advance. Not only does this alleviate strain on bandwidth and resources at the beginning of an event, it also reassures those attending that they are adequately prepared and will be able to quickly connect at the start of their session. If you’d like more information about other options to package or distribute the NHWC client across all the computers within your network, please contact our support team, at [email protected].
Presentation Tools with Configurable Bandwidth Throttles and Caps
The following three tools have a range of settings that can be capped and defaulted at different speeds. You can control their impact to your network, as well as at what speed and quality level participants receive data. The benefit of this ability to customize your settings is that if you have a session that has all end-users joining on a dial up connection, the leader can lower the settings so that they don't get "left behind" in the presentation.
1. Application Sharing (or “Appshare”) has a range of 14 - 500 kbps and can be set to any of the following: 14k, 30k, 50k, 90k, 100k, 200k, or 500k+. Please note, that using 100kbps Appshare for instance, does not mean that the leader or presenter is constantly sending a 100kbps stream of data to the server, that the server is then feeding out to each NHWC client. In fact, the 100kbps setting actually means that 100kbps is the maximum that would be sent. In this example, when the leader starts sharing, the initial screen rendering may take as much as 100kbps. After the initial image is rendered, the NHWC client only updates or sends the portions of the screen that change. So if a document is opened and shared and is being viewed with no movement on the presenter’s machine, bandwidth utilization will drop off to very little, even though Desktop or Application sharing is actively being used.
The default setting for Application sharing is 100kbps, at a 16-bit color depth. This has been found to perform efficiently and quickly for a wide range of participants, from people in office buildings with dedicated T1 lines, to smaller or residential offices with cable modems and DSL connections.
Additional Users Downloading Client & Joining a Session Already
a. In the following graph, the first teal peak, is the initial launch of 100kbps desktop sharing. The subsequent 2nd through 7th peaks, are major full screen changes, minimizing and maximizing a series of programs, causing the entire desktop resolution to be resent. While the 8th peak, is when the Markup / Annotation tools were engaged, with the following much smaller peaks, representing Appshare markups being relayed to the NHWC Clients.
b. In addition to the speed setting for Application Sharing, there are also several settings for color depth, which allow you to choose from grayscale, 256, 16-bit, and 24-bit color spectrums. While the color settings don’t directly impact the bandwidth throttle, being conservative with colors causes less data to be sent. For instance most computer programs, documents, spreadsheets etc, are very appropriately viewed in 16-bit color, while some DOS or command window based programs can even be viewed and presented with 256 color, thus conserving bandwidth to send only mouse movements and screen updates. Appshare # of users 10 50 100 250 500 1000 1500 2000 Se t in KBP S 14 140 700 1,400 3,500 7,000 14,000 21,000 28,000 30 300 1,500 3,000 7,500 15,000 30,000 45,000 60,000 50 500 2,500 5,000 12,500 25,000 50,000 75,000 100,000 90 900 4,500 9,000 22,500 45,000 90,000 135,000 180,000 100 1,000 5,000 10,000 25,000 50,000 100,000 150,000 200,000 200 2,000 10,000 20,000 50,000 100,000 200,000 300,000 400,000 500 5,000 25,000 50,000 125,000 250,000 500,000 750,000 1,000,000
2. VOIP has a range of 8 - 24 kbps and can be set to 8k, 12, or 24k. Just as with most phone conferencing bridges, users who are not actively speaking are likely to mute themselves or be muted by the facilitators. This is a great way to conserve bandwidth, as well as eliminate background noise when only one or two key presenters are speaking. Coincidentally, the codecs NHWC uses do utilize silence detection so that if a person is not muted, but is not speaking, their microphone will not be sending data and utilizing bandwidth.
a. In the following graph, the sample shown is of two presenters having a conversation utilizing 12kbps, at the end of which they unmute all the attendees to have a brief roundtable discussion of the topic recently presented. The bandwidth increases from 24kbps to a maximum of 144kbps, when the conversation goes from 2 to 12 active microphones. Although, as the lines illustrate, the amount of data sent and received Initial share Full screen changes Markups relayed Markup Tools Engaged
Mitel NetSolutions Hosted Web Conferencing User Guide 178 | P a g e fluctuates below that maximum with the ebb and flow of conversation, rarely is everyone speaking at the exact same time.
N-way VOIP # of users
2 5 10 15 25 50 100 250
kbps
8 16 40 80 120 200 400 800 2,000
12 24 60 120 180 300 600 1,200 3,000
24 48 120 240 360 600 1,200 2,400 6,000
3. Video has a range of 2 – 15 fps as well as three choices for image size, 176x144, 352x288, & 640x480.
When choosing your frame rate and image size in the NHWC communication center, the bandwidth required for one video is displayed, for instance the 176x144 video size, at 15 frames per second, uses approximately 96kbps. Changing these settings updates that number on screen, making it very easy to gauge the maximum amount of bandwidth that would be used in an NHWC session.
With version 9 of NHWC, we introduced updated codecs for video. One of the greatest advantages to this, especially given the ability to use “multi-point” video, with several individual’s camera’s displayed simultaneously, is that these codes, function similar to our application sharing tool. Once the initial image is rendered, the codec detect and only sends updates for that portion of the image that has moved or changed.
That being said, with the settings listed above, one person sending video, will not use more than 96kbps, and and three people with cameras turned on and viewing each other in session will not use more than 288kbps, but their average bandwidth will be less, unless their entire camera image or backdrop is in motion.
In the following graph, there are three distinct plateaus, in this session initially the leader only had their camera on, then an assistant turned a 2nd camera on, finally another assistant turned on a 3rd camera. After all three cameras were on, they were then turned off in the same order they were turned on, corresponding with the step-down in bandwidth utilization. Notice on each plateau there are a series of ridges and valleys, due to the fluctuation in how much of the image has to be updated, remembering that with two or three cameras enabled those ridges and valleys depict that cumulatively for all the cameras that are on at the time.
Unmute all microphones
Please note, within NHWC when the camera is not enabled/visible, video data is not being sent. This varies from several of our competitors that continue to allocate or utilize bandwidth for video even when those cameras are not visible.
Video # of users frame rate size kb 5 10 15 20 25 50 Configuration sm (176x144) 2 16 80 160 240 320 400 800 sm (176x144) 5 64 320 640 960 1,280 1,600 3,200 sm (176x144) 15 96 480 960 1,440 1,920 2,400 4,800 md (352x288) 10 128 640 1,280 1,920 2,560 3,200 6,400 md (352x288) 15 196 980 1,960 2,940 3,920 4,900 9,800 lg (640x480) 5 256 1,280 2,560 3,840 5,120 6,400 12,800 lg (640x480) 15 512 2,560 5,120 7,680 10,240 12,800 25,600
Presentation Tools That Utilize a Standard HTTP(S) Request
The following three NHWC tools utilize a standard http(s) request, and will attempt to use all the bandwidth available to them until the request is fulfilled. For the Synchronized Web Browser and Powerboard, the screen changes initiate the requests. When no screen changes are occurring, little or no bandwidth is used.
1. NHWC’s Synchronized Web Browser actually uses each local machine’s default Web browser to display a webpage inside the NHWC interface. In this case, the only information being passed between the NHWC server, and the NHWC Clients, is the Web address itself. Because it is the local browser, it will obey all existing network rules. If certain websites are restricted, for
Mitel NetSolutions Hosted Web Conferencing User Guide 180 | P a g e example, then an attendee in session would see the same prompt as if they had opened their browser and tried to navigate to the Web address themselves.
For the sake of discussion, let’s consider YouTube.com. As NHWC presenters wanting to bring in current topics for discussion, we add the URL http://www.youtube.com/watch?v=DM2Ll- _hFgo to our content library. When we launch the content item in session, each person’s individual computer will receive that URL from the NHWC server, and then their local browser will go directly to that address to retrieve the page.
Each person can then click on and navigate through their page individually, or when the presenter or an assistant clicks, it will drive all attendees to that same URL.
In this case the bandwidth impact to your network will be determined by the websites being navigated, multiplied by the number of people in session.
Synch Browser # of users
10 50 100 250 500 1000 1500 2000 "page size" in kb Google.com 20 200 1,000 2,000 5,000 10,000 20,000 30,000 40,000 Support.NHWC.com 96 960 4,800 9,600 24,000 48,000 96,000 144,000 192,000 Wikipedia.com 124 1,240 6,200 12,400 31,000 62,000 124,000 186,000 248,000 NHWC.com/greenmeter 204 2,040 10,200 20,400 51,000 102,000 204,000 306,000 408,000 cnn.com 429 4,290 21,450 42,900 107,250 214,500 429,000 643,500 858,000 microsoft.com 1060 10,600 53,000 106,000 265,000 530,000 1,060,000 1,590,000 2,120,000 apple.com 1160 11,600 58,000 116,000 290,000 580,000 1,160,000 1,740,000 2,320,000 * all numbers displayed above were based on website as configured on 3/1/2008
2. Streaming Videos, also referred to as “AV-Links” or “Media-Links” are very similar in
functionality to Synchronized Web Browser listed above. The significant difference being that instead of using each person’s local browser, this function calls on the local machine‘s media player to play back a URL. Again, the only information passed between the NHWC server and clients with this tool is the URL for the video or music file. Actual bandwidth utilized by the end-user is determined by the codec / quality or overall size of the video or music file being viewed.
Please note, because this tool uses the local media player, if an end-user doesn’t have the correct codec on their local machine when a “Media-Link” is launched, that end-user may experience a slight delay, while their local media player automatically retrieves the correct codec to play back the file.
AV Links # of users 10 50 100 250 500 1000 1500 2000 Size of media in kb 788 7,880 39,400 78,800 197,000 394,000 788,000 1,182,000 1,576,000 876 8,760 43,800 87,600 219,000 438,000 876,000 1,314,000 1,752,000 1450 14,500 72,500 145,000 362,500 725,000 1,450,000 2,175,000 2,900,000 2670 26,700 133,500 267,000 667,500 1,335,000 2,670,000 4,005,000 5,340,000 3140 31,400 157,000 314,000 785,000 1,570,000 3,140,000 4,710,000 6,280,000 5830 58,300 291,500 583,000 1,457,500 2,915,000 5,830,000 8,745,000 11,660,000
3. NHWC’s Powerboard converts an uploaded PowerPoint, into a series of still images, each slide becoming one image. There are quality settings for both image resolution, 1024x768, or 1280x1024, as well as image quality GIF, or JPG.
The following graph illustrates a leader, choosing to upload an 18-page presentation, after joining the NHWC session, illustrated by the dark blue line. Then while in session, the leader launches the same 18-page uploaded file, which causes each NHWC client to initially download the first slide, and then immediately begin to buffer the next two slides.
The initial launch is illustrated by the tallest teal colored peak. As the presenter walks through the presentation, the Powerboard is always buffering two slides ahead. The subsequent smaller series of peaks show that the Powerboard is buffering and keeping everyone in the session synchronized on the same page, regardless of their different bandwidth connections. Skipping from page 6 to page 11, for example, may cause a slight delay as the Powerboard then has to retrieve that slide out of sequence and will then immediately buffer pages 12 and 13. These are standard http(s) requests prompted by the page turn, so navigating to page 12 prompts it to buffer page 14 and so on.
Initial launch of
Mitel NetSolutions Hosted Web Conferencing User Guide 182 | P a g e PowerBoard # of users quali ty size kb 10 50 100 250 500 1000 1500 2000 configuration 1024 x 768 GIF 540 5,400 27,000 54,000 135,000 270,000 540,000 810,000 1,080,000 1024 x 768 JPG 310 3,10 0 15,5 00 31,0 00 77,50 0 155,0 00 310,0 00 465,00 0 620,00 0 1280 x 1024 GIF 990 9,900 49,500 99,000 247,500 495,000 990,000 1,485,000 1,980,000 1280 x 1024 JPG 580 5,800 29,000 58,000 145,000 290,000 580,000 870,000 1,160,000 Summary
Typically most sessions only utilize one or two tools simultaneously, depending on the goals of that session. By looking at what tools are typically being used in your company's sessions it is pretty easy to calculate the average amount of bandwidth.
Let’s assume that a typical session consists of walking through a program that’s being presented through Application or Desktop Sharing (and sharing is capped at 100kbps) and uses video primarily for introductions. In this example, the primary bandwidth concerns are going to be the Application Sharing and brief video usage. Therefore the connection would average out to be a little over 100kbps for each NHWC Client in the session, assuming moderate use of text chat along with some other tools at the same time.
C.
Troubleshooting
In this Appendix:
• Communications Center Issues
• Session Issues
• Session Tools Issues o Text Chat
o Application Sharing
This document provides troubleshooting information for the NHWC Communications Center and the NHWC Client. Issues are addressed by subject area. If these solutions do not solve your problem, please contact NHWC Customer Service.