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Cisco WebEx Meeting Center

Cisco WebEx Network Bandwidth White Paper

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Contents

Introduction. 3

Optimized Bandwidth Usage. 3

Optimized Desktop and Application Sharing. 3

Compression and Encryption. 3

Incremental Update. 3

Video Compression. 3

Optimal Protocols. 3

WebEx Data Share. 4

WebEx Video. 4

Supported Platforms. 5

Video Features for Mobile clients. 5

System Requirements. 6

Supported Cameras. 6

WebEx Video Modes. 7

Streaming a Video File in to a WebEx Meeting. 9

About the WebEx Video Codec. 10

Frame-Rate Range. 10

Site-Level Control 10

User Interface. 11

User-Level Controls. 11

Network Adaptation. 13

Bandwidth Bottleneck Detection. 13

Dynamic Parameters. 13

Collaboration Meeting Room Hybrid. 13

Network-Based Recording: Recorded Video Resolutions and FPS.. 15

Bandwidth Data. 15

Measurements and Methodology. 15

Measurement Scenarios for Mobile Clients. 16

Average Video Bandwidth Consumption. 16

Maximum Video Bandwidth Consumption. 17

Examples of the Bandwidth Consumption for Video Use Only (No Data and No WebEx Integrated VoIP) 17

Streaming Video File: Bandwidth Consumed. 18

Collaboration Meeting Room Bandwidth Requirements. 19

Network Traffic Summary for Data Presentation on Mobile Devices. 20

Network Traffic Data Comparison Chart 20

Common Problems and Location of Log Files. 21

Video Statistics Window.. 22

Summary. 23

For More Information. 24


Introduction

The performance of a Cisco WebEx® session depends on many factors. Some of these factors can be administratively controlled within the WebEx admin user interface, and the Cisco® Collaboration Cloud, whereas others can be managed within the customer’s corporate network or home computing infrastructure. In this paper, we provide measurements for the network bandwidth generated during a WebEx session. This document also describes Cisco WebEx high-quality, high-definition (HQ and HD) video technology and provides details on how it works in the context of your meetings. Finally, this paper also offers information about storage capacity required for Network-Based Recording (NBR) functions. This paper does not contain information about the Cisco Jabber® client.

Optimized Bandwidth Usage

Cisco WebEx services optimize bandwidth usage to lower the amount of data transmitted over the network, helping to reduce network congestion, increase performance, and improve your experience. The most significant optimizations follow.

Optimized Desktop and Application Sharing

The client software monitors text and graphics, and shared document views are transmitted. Incremental changes are detected and only these changes are transmitted again, fully optimizing the bandwidth use and preserving the user experience.

Compression and Encryption

All large data transfers and file uploads are compressed, not only reducing network traffic, but also adding a level of encryption to the data stream. For more information about Cisco WebEx security, refer to our security white paper at http://www.webex.com/includes/documents/security_webex.pdf.

Incremental Update

During application sharing, the contents of the window are dynamically updated. WebEx services incrementally update only those portions of the screen that have changed. The updates are transmitted as vector graphics commands and not as bitmaps.

Video Compression

Several video compressions and optimizations have been incorporated into WebEx HQ and HD video. The amount of bandwidth produced by video transmission is directly related to the rate of change of captured video images.

Optimal Protocols

WebEx services can work through all firewalls using the Secure HTTP (HTTPS) protocol. However, WebEx will first check if communication can be established using the User Datagram Protocol (UDP). This approach is more efficient and reduces network traffic by approximately 10 percent when compared to HTTPS. Security is achieved with use of the Transport Layer Security (TLS) 1.0 (Secure Sockets Layer [SSL] 3.0) standard protocol.

WebEx Data Share

Cisco WebEx services create data streams that vary depending on the type of application being shared, complexity of the graphics, use of voice over IP (VoIP), use of video, and other factors. WebEx services typically create network traffic when users actively share slides, desktop, and video; or use VoIP. Simply viewing a slide presentation does not generate any activity in the meeting and transmits very little network traffic. Intense activity, such as changing a PowerPoint slide, generates intermittent spikes in network traffic, with a return to low bandwidth use while there is no activity or no changes on the shared screen. WebEx data sharing provides up to five frames per second (fps) refresh rate, requiring presenters to use the Streaming Video Share feature for sharing video from their computers (refer to the next section for details). The Data Share or Presentation Share features should not be used for streaming a video file during a meeting. Figure 1 illustrates how to share your desktop.

Figure 1.     How to Share Your Desktop

WebEx Video

Cisco WebEx Video allows you to share video by using the web cam attached to your PC or Mac machine, or you can share and receive it on some mobile devices. High definition (HD) with resolution up to 720p is now available in Cisco WebEx Meeting Center and Training Center, and high quality (HQ) with up to 360p resolution is available in other centers. You can review details about WebEx web cam video usage options and supported hardware in this section. Table 1 lists our video products and their features, and Table 2 lists the video resolutions that WebEx Video supports.

Table 1.       High-Quality and High-Definition Cisco WebEx Video At A Glance

 

High-Definition Video

High-Quality Video

Products

  Cisco WebEx Training Center (WBS28SP4 or later)
  Cisco WebEx Meeting Center
  Cisco WebEx Support Center
  Cisco WebEx Event Center

Resolutions

Maximum resolution (pixels) Maximum frame rates (per second)

 

  720p (1280x720)

 

  360p (640x360)
  30 fps
  30 fps

Transport protocol

  SSL 443
  UDP port 9000
  SSL 443
  UDP port 9000

Maximum number of participants

  500 (HQ and HD)
  500 (HQ; WebEx Training
  Center only) 1000 in EC

Video codec

  H.264
  H.264

Table 2.       High-Quality and High-Definition Video Resolutions

 

Format

Display Size

 

 

Width

Height

Full screen

720p

1280

720

Large view

360p

640

360

Medium view

180p

320

180

Thumb view

90p

160

90

Supported Platforms

The following platforms support Cisco WebEx Video.

   Windows

   Linux (view only for HQ; no support for HD video)

   Mac

   iOS on iPad

Video Features for Mobile clients

WebEx multipoint video is supported on Android, Apple iOS, Blackberry, and Windows Mobile. It offers:

   Video wall of 90p thumbnail videos

   Full-screen video mode

   Ability to receive up to 360p video

   Ability to send up to 180p video (iPad 2 and above for iOS tablets)

System Requirements

Table 3 lists the system requirements for Cisco WebEx Video.

Table 3.       CPU and Memory for Cisco WebEx Video (for PC and Mac)

Best Encoded (Sending) Resolution

Best Decoded (Receiving) Resolution

Minimum CPU Requirement

Memory

Requirement

720p

720p

  Quad core (sending only in a meeting with three or more participants)
  Dual core 2.8 GHz or dual core 2.4 GHz with Intel HT (send with a maximum of two participants; receive with three or more participants)

2 GB

360p

720p

Dual core

2 GB

360p

360p

Dual core

1 GB

180p

360p

Single core 2.4 GHz

1 GB

180p

180p

Single core with less than 2.4 GHz or Intel Celeron

None

Supported Cameras

Cisco WebEx Video supports HD for the cameras listed below. (Refer to the latest WebEx release notes for the updated list.)

   Logitech HD Webcam C310

   Logitech HD Webcam C500

   Logitech HD Webcam C510

   Logitech HD Webcam C905/B905

   Logitech HD Pro Webcam C910/B910

   Logitech HD Webcam C920

   Microsoft LifeCam HD-5000/HD-5001

   Microsoft LifeCam HD-6000

   Microsoft LifeCam Cinema

   Microsoft LifeCam Studio

   Cisco Precision HD

   Cisco VT Camera III

   Apple iSight HD

Cisco WebEx Video supports HQ for the cameras listed below. (Refer to the latest release notes for the
updated list.)

   Cisco VT Camera II

   Cisco VT Camera III

   Cisco Precision HD

   Logitech HD Webcam C920

   Logitech Quick Cam Pro 9000

   Logitech QuickCam Orbit AF

   Logitech QuickCam C905

   Logitech QuickCam S7500

   Logitech HD Pro Webcam C910

   Microsoft LifeCam HD

   Microsoft LifeCam VX-1000

   Microsoft LifeCam Cinema

   Microsoft LifeCam VX-6000

   Microsoft LifeCam NX-6000

   Microsoft LifeCam VX-3000

WebEx Video Modes

WebEx Video provides two types of operation modes: single-point video and multipoint video. WebEx Support Center includes only point-to-point video to support the most common type of interaction between a support representative and the customer.

Multipoint video provides a main active speaker window and thumbnail windows where up to six participants can be viewed simultaneously in the participant list view; or up to five in the full-screen view. Each user has the flexibility to scroll through the alphabetical list of participants. It is preferred for highly collaborative group meetings where multiple people are actively participating. Figure 2 demonstrates what a multipoint video looks like. Multipoint video is preferred for collaborative meetings or training sessions where multiple attendees are actively participating.

Figure 2.     U ser Interface of a Mul tipoint Video Mee ting

If you wish to display only one participant video at a time, then when scheduling your WebEx session, simply disable the thumbnail view option. This will limit the number of active videos to one (see Figure 3).

Meeting participants can customize their own views between the active speaker only and thumbnail view. Participants can customize either through the Meeting Options menu or by right-clicking the video panel title and selecting the video mode.

Figure 3 displays the options you have when setting up a meeting.

Figure 3.     Meeting Options

Streaming a Video File in to a WebEx Meeting

Streaming a video file in to a WebEx meeting allows you to share a video file during a meeting. This method of video sharing is different from the desktop sharing and the website sharing features. Similar to webcam video, streaming uses scalable video coding to encode and decode multiple layers of video bit streams.

In Cisco WebEx Meeting Center, Training Center, and Event Center, you should distinguish between the webcam video usage for video presence of the participants in the meeting and the shared video file feature, which the presenter uses to play the video file to the audience from the presenter’s computer. The webcam video refers to videoconferencing in real time, encoded and sent to the receiving clients using the Cisco Collaboration Cloud.

Webcam video is used primarily for videoconferencing. The Streaming Video File feature is a video that is encoded and streamed to other meeting participants as shared content during a meeting. This streaming video feature contains the video and audio (if it is included in the file) and does not appear in a multipoint videoconferencing pod as an active speaker. You can play, pause, or stop it from the file-sharing tab; it is similar to a previously uploaded presentation or whiteboard (refer to Figure 4).

From the Presentation Desktop, click the arrow next to Share My Desktop, select Share File, and select your video file. The following media file formats are currently supported: WMV, WMA, WAV, MP3, ASF, AVI, MPG, MPEG, MOV, FLV, F4V, QT, and MP4 and WRF. (Note: The computer of the person sharing the file must be capable of playing the file).

Figure 4.     How to Stream a Shared Video

About the WebEx Video Codec

The Cisco WebEx Meeting Center has adopted the H.264 standards-based Scalable Video Coding (SVC) for video compression to deliver adaptive standard-quality (SQ), high-quality (HQ), and high- definition (HD) video. HD (720p) video is currently available in Meeting Center and Training center.

The video engine consists of all the fundamental video processing modules, including capture, encoding, transmission, receiving, decoding, and rendering. It also includes supporting modules for error control, congestion control, bit-rate adaptation, and encryption.

The SVC encoding protocol allows the captured video to be separated into multiple layers of resolutions, frame rates, and quality. In the WebEx video encoder implementation, raw video sequences are compressed into a single base layer and several enhancement layers before they are transmitted to the receiving clients. The base layer in the compressed video bit streams provides a relatively low video quality and can be independently decoded. Enhancement layers serve as add-ons for the base layer to improve the video experience. If more bandwidth is available, then more enhancement layers will send, resulting in better video quality.

Similarly, when network congestion occurs for any participants, the clients could save bandwidth by receiving fewer enhancement layers, gradually degrading the video quality while maintaining the best video experience and dynamically adjusting the quality to changing conditions of the network or the participant’s computer.

Depending on various conditions, such as user eligibility, subscription modes of the receivers, capability of camera and PC, network conditions, and others, one or more of the available resolutions can be encoded at the same time that the video is sent. On the receiving side, the client automatically selects and decodes one specific resolution. This encoding and decoding capability results in a higher bandwidth requirement for transmitting video compared to receiving video.

Frame-Rate Range

WebEx supports various frame-rate ranges. On the sender side, it depends on the camera capture capability and available computing and bandwidth resources. On the receiver side, it depends on the bandwidth and computing resources.

   Up to 30-fps HQ and HD video is supported in a one-on-one meeting (only two participants point to point [P2P]).

   Up to 24-fps HQ and HD video is supported in a multipoint meeting (three or more participants).

   Up to 18-fps 180p video is supported in a one-on-one meeting (only two participants P2P).

   Up to 12-fps 180p video is supported in a multipoint meeting (three and more participants).

   The WebEx client may stop sending and receiving the video if the network or hardware environment conditions deteriorate drastically.

Site-Level Control

Administrators cannot control the default and maximum bandwidth levels for multipoint HQ and HD video.
The levels and frame rates are controlled automatically by software, and administrators cannot override the software control. Administrators can choose to disable the HQ/HD mode and limit the video to 180p resolution. Refer to Figure 5 for the “Turn on high-quality video” or “Turn on high-definition video” checkboxes. This setting is a site wide-setting that affects all users. Refer to the site administrator’s guide for more details.

Figure 5.     Enabling HQ and HD Video

Figure 6 shows the HQ and HD settings available for a user profile.

Figure 6.     HQ and HD Settings

Figure 7 illustrates the settings available for meeting scheduling.

Figure 7.     HQ and HD Meeting Scheduling Settings

User Interface

User-Level Controls

Most of the time, the bandwidth that the video streams consume on your network depends on the type of video view modes. Table 4 provides an example of the different modes with video and average bandwidth usage. You can use information from this table to calculate the approximate bandwidth consumption per client.

Table 4.       Modes with Video and Average Bandwidth Usage

UI Mode

Definition               

Default Video Resolution

Default Frame Rate (fps)

Default Receiving Bandwidth per Video Channel

Screenshots

Thumbnail view

One active speaker plus up to six thumbnail videos

90p (up to six thumbnails)

 

 

180p (active)

Six (multipoint*) Six (P2P*)

 

 

12 (multipoint)

12 (P2P)

64 kbps (multipoint)

64 kbps (P2P)



180 kbps (multipoint)

180 kbps (P2P)

List view

Only one active speaker on the panel

180p (active)

12 (multipoint)

12 (P2P)

180 kbps (multipoint)

180 kbps (P2P)

Application sharing

Only one active speaker video

180p

12 (multipoint)

12 (P2P)

180 kbps (multipoint)

180 kbps (P2P)

Full-screen video mode with thumbnails

One large video of the active speaker, plus up to five thumbnail videos

360p (active)

24 (multipoint)

24-30 (P2P)

520 kbps (multipoint)

520-640 kbps (P2P)

HD expanded full-screen video mode

One video of the active speaker, increased up to the display monitor size

720p

24 (multipoint)

15 - 30 (P2P)

1490 kbps (multipoint)

1260 - 1820 kbps (P2P)

 

   *Note: P2P refers to meetings with a maximum of two participants. Multipoint refers to meetings with three or more participants.

   Both multipoint and P2P video sessions go through the WebEx cloud.

   The active, or main, speaker video window can be enlarged to up to 360p resolution by dragging the sides of the main video panel.

Network Adaptation

All video resolutions listed in Table 4 are the default target resolutions. They are based on the assumption of a perfect network environment. In the video engine design, Cisco has implemented network adaptation to promote smooth transition from lower-quality to higher-quality video, and conversely. Between the default target resolutions, fps, and bandwidth (90p, 180p, 360p, and 720p), you can send and receive other temporary resolutions to allow graceful adaptation of the video quality to current conditions.

Bandwidth Bottleneck Detection

One of the most common network problems is insufficient or unreliable bandwidth. Bandwidth limitation can cause packet loss, delays, and jitters. In addition, if the required sending and receiving bit rates exceed the bandwidth limitations of the network, network congestion will occur and eventually results in a poor video experience. During the video session, the client software closely monitors the transmission and packet-loss rates through the Real- Time Transport Control (RTCP) feedback protocol. When changes in network conditions are detected, the quality- of-service (QoS) module allocates bandwidths for a voice over IP (VoIP), data, and video session. The video session then adjusts the outgoing bit streams through encoder control. After the network condition becomes stable, the QoS module, together with the encoder control module, upgrades the video experience if the bandwidth allows it. This QoS prioritization is for the WebEx client software operation.

Dynamic Parameters

The bandwidth bottleneck detection is a function to probe the current bandwidth capability by sending and receiving network test packets. The probing results are used to guide the network adaptation process as described in the previous section. In general, bandwidth bottleneck detection is at:

   The start of a meeting

   When the video start or stop button is pressed

   Before upgrading video resolution to the next level that involves a significant bandwidth gap

Collaboration Meeting Room Hybrid

Cisco TelePresence® integration with the Cisco WebEx Meeting Center web conferencing service can enable transparent voice, video, and data sharing between Cisco TelePresence environments and remote Cisco WebEx users. This integration extends the reach of a Cisco TelePresence meeting to remote participants.

Figure 8 shows a picture of the participants list with a Cisco WebEx Enabled TelePresence meeting as viewed by the WebEx participant and meeting information screenshot.

Figure 8.     Participants List in a Cisco TelePresence Meeting

You can limit WebEx participant bandwidth in the Cisco TelePresence Management Suite Version 14.2 or later. The recommended bandwidth is 2048 (refer to Figure 9).

Figure 9.     Limiting WebEx Participant Bandwidth

Network-Based Recording: Recorded Video Resolutions and FPS

The Network-Based Recording (NBR) feature allows the meeting host and participants to record the meeting and play the recording of that meeting at some later time. Refer to the Cisco WebEx NBR user guide for more information about the NBR feature.

Table 5 provides the default maximum encoding parameters for P2P and multipoint video mode with NBR, and Table 6 gives the average storage size when using NBR.

Table 5.       Default Maximum Encoding Parameters for P2P and Multipoint Video Mode with NBR

P2P or Multipoint Video Session

Recorded Resolution

Encoding Bit Rate

Frame Rate (fps)

Multipoint (three or more participants)

180p

180 kbps

Up to 12

P2P (two participants only)

180p

180 kbps

Up to 12

P2P (two participants only)

360p

520 kbps

Up to 30

P2P (two participants only)

720p

1810 kbps

Up to 30

Table 6.       Average Storage Size When Using NBR

Meeting Content

Approximate Storage Per 1 Hour of Recording

Application sharing

36 MB per hour

Voice

30 MB per hour

180p video

104 MB per hour

360 HQ video

337 MB per hour

720p video

987 MB per hour

Note:    Note: Webcam videos are stored as the original resolution during NBR recording. However, during NBR playback the playing video resolution is restricted to 180p.

Bandwidth Data

Measurements and Methodology

Bandwidth measurements for this paper were taken primarily on Cisco WebEx Meeting Center. However, note that the underlying architecture for WebEx services is common across all Cisco WebEx meeting services (Meeting Center, Training Center, Event Center, and Support Center) and uses the same network traffic.

For this paper, the bandwidth requirements were measured under the following conditions and scenarios:

   Idle (single static presentation slide, no changes, and no slide transitions)

   Presentation share (single file uploaded to meeting)

   Desktop and application share

   Integrated WebEx VoIP (public switched telephone network [PSTN] audio was not part of this test)

   Video (various web cams in HQ and HD modes)

These test scenarios were created to emulate typical usage circumstances and identify how much network traffic resulted from these activities. The test also identified the high and low ranges of expected traffic to help you better understand the potential impact of WebEx on your network.

Measurements were conducted by using various development tools. For the baseline, the test measured idle network traffic to help ensure information packets were not influenced by other network activities. Each test was executed multiple times to get an average result for each scenario.

During a video-enabled WebEx meeting, a portion of the network bandwidth is consumed by the video bit streams that are being transmitted and received. The actual bandwidth consumption can be affected by admin or user- level settings and by network conditions.

The test used BlackBerry Bold 9700 (BB). The traffic was monitored with the Mobile Data Alerter software. For iPhones and iPads, the testing team used the actual devices connected to a Mac and a traffic-monitoring tool to monitor data usage. PC tests were run with Window clients. All measurements were captured locally with the Iris Network Analyzer tool. The testing team also monitored the inbound and outbound HTTP traffic from the PCs and other devices to the Cisco Collaboration Cloud. Measurements were captured from both the presenter’s machine and the attendee’s machine. There was no significant difference in the bandwidth for data sharing; therefore tests related to data sharing assume both presenter and attendee traffic to be the same.

All measurement results are in kilobits per second (kbps), not kilobytes (KB). File sizes are measured in kilobytes (KB). A byte is eight bits; a kilobyte is 1024 bytes. Eight bits multiplied by 1024 equals 8192 bits. Transmission rates are also measured in kilobits per second (not kilobytes).

Measurement Scenarios for Mobile Clients

   Idle: Baseline network traffic in a meeting

   Presentation share: Presenter shares a PowerPoint presentation with graphics and animations

   Desktop share and application share: Presenter shares a desktop, running a PowerPoint presentation with 30-second transitions

   Internet phone (VoIP): Presenter and attendees have a conversation using PC microphones

Average Video Bandwidth Consumption

Table 7 gives the average bandwidth consumption for each of the video configurations.

Table 7.       Average Bandwidth Consumption

Session

HD

HQ-Active Video

Source

720p

180p

360p

Six thumbs at 90p

One 180p + six thumbs at 90p

Sender traffic (kbps)

1750-2380

330

911

-

-

Received traffic

1260-1820

245

635

313

482

These results are for video traffic only; add an average of 70 to 150 kbps for VoIP traffic (send and receive).

Table 8 summarizes the average measurements. Each measurement is dependent on what the camera sees. Video traffic will increase and can be reduced based on the moving subject. The audio traffic average should be added to the total average numbers. Data presentation traffic is variable and dependent on the shared content and change rate. Table 8 includes examples of the video bandwidth measured during the test, with faster-moving versus slow-moving or static subjects used in the test file. Note the minimal differences between the TCP and User Datagram Protocol (UDP) protocols used; however, note the bandwidth usage difference between the static subject and slow- and faster-moving video subjects.

Table 8 gives test results for HQ-Active Video tests.

Table 8.       Test Results for HQ-Active Video Tests

Session

HQ-Active Video

Camera

Logitech 9000

Logitech LS 7500

Cisco Camera VT III

Source

Slow-moving subject

No moving

Slow-moving subject

No moving

Faster-moving subject

180p

360p

180p

180p

360p

180p

180p

360p

UDP

TCP

UDP

TCP

UDP

TCP

UDP

TCP

UDP

TCP

UDP

TCP

UDP

TCP

UDP

TCP

Sender traffic (kbps)

271

264

881

975

72

89

290

308

888

923

59

58

320

330

911

991

Received traffic (kbps)

220

235

603

631

47

57

228

244

604

628

54

46

261

245

609

635

Maximum Video Bandwidth Consumption

The bandwidth required to send the video is higher than the required bandwidth for receiving the video. SVC technology used in the client software uses the multilayer frames to send video and allows the client to automatically select the best possible resolution to receive the video. Table 9 gives results for the tests measuring video bandwidth consumption.

Table 9.       Video Bandwidth Consumption

 

 

Maximum Bit Rate (Send)

Maximum Bit Rate (Receive)

High-definition

720p (1280x720)

3.0 Mbps

2.5 Mbps

High-quality

360p (640x360)

1.5 Mbps

1 Mbps

Standard quality

180p (320x180)

0.5 Mbps

0.5 Mbps

Six thumbnails

90p

-

0.5 Mbps

One thumbnail

90p

50 kbps

-

The site administrator can set the video quality for the entire site and at the host account level, and the host can set those parameters when scheduling the meeting. Attendees have no control over the video quality; it is controlled automatically during the meeting based on various factors. The host can schedule the meeting with a maximum video resolution up to 720p (WebEx Meeting Center and Training center), 360p, or 180p. Thumbnail video is always set at 90p, and it cannot be changed.

Each resolution can support variable frame rates: HD (720p) at 24-30 fps; HQ (360p) at 24-30 fps; SQ (180p) at 12 fps; and thumbnail video at 6-10 fps.

Examples of the Bandwidth Consumption for Video Use Only (No Data and No WebEx Integrated VoIP)

Note that the client can display one main window with an active speaker, meaning that at any time when people are speaking, their videos appear in the main, enlarged window. In addition to the main active speaker window, a client can view up to six additional scrollable thumbnail views in the participant list, and up to five additional scrollable thumbnail windows in full-screen mode. There are no thumbnail images in the expanded full-screen video in HD mode (Meeting Center only).

Scenario 1: Three participants in the meeting, all capable of sending and receiving video at 360p:

   Multipoint video window (360p) plus two (90p) thumbnails on received view

   Send: 900 from webcam = 900 (one Mbps) average per participant for video stream

   Receive: 600 plus (2 x 40) = 680 (0.7 Mbps) average per participant for video stream

Explanation: Each client will try sending an average of 1 Mbps or up to a maximum of the 1.5 Mbps of data. Each client will also receive an average of 600 kbps or up to a maximum of the 1 Mbps of data. The receiving client can also use additional bandwidth for the thumbnail views if enabled (2 x 4 0 kbps on average). To use additional bandwidth, the data-sharing portion (kbps are hard to predict) and possible WebEx VoIP usage (70-150 kbps if enabled) must be added.

Scenario 2: Eight participants in the meeting with 180p video (non-HQ):

   Multipoint video window (180p) plus six (6 x 90p) thumbnails received view

   Send: 320 from webcam equals 320 kbps (0.3 Mbps) average per participant for video stream

   Receive: 250 plus (6 x 40) = 490 kbps (0.5 Mbps) average per participant

Explanation: HQ video is disabled. Each client will send 350 kbps on average, or up to 0.5 Mbps maximum. Each client will receive an average 250 kbps for the main active speaker window plus an optional six thumbnails (6 x 40) average equal to 0.5 Mbps on average on the receiving side per participant with thumbnail view enabled. For this scenario, the data-sharing portion (kbps are hard to predict) and possible WebEx VoIP usage (70-150 kbps, if enabled) must be added.

Streaming Video File: Bandwidth Consumed

Actual sending and receiving bit rates are independent of which multimedia file format is used. Before transmission, shared multimedia content is first extracted and transcoded into an H.264 SVC bit stream. When the participating client receives the bit stream, the stream is decoded and then rendered by the video engine for display. Average bandwidth usage measurements are listed in Table 10.

Table 10.     Average Bandwidth Used

File Format

Sent and Received

Video Only

Video Plus Audio

flv

Sender traffic (kbps)

932

1282

Receiver traffic (kbps)

697

989

avi

Sender traffic (kbps)

984

1271

Receiver traffic (kbps)

730

976

wmv

Sender traffic (kbps)

1225

1261

Receiver traffic (kbps)

906

968

mov

Sender traffic (kbps)

980

1273

Receiver traffic (kbps)

723

964

wav

Sender traffic (kbps)

-

96 (audio only)

Receiver traffic (kbps)

-

96 (audio only)

Collaboration Meeting Room Bandwidth Requirements

The bandwidth requirement for Cisco Collaboration Meeting Rooms (CMR) is different from the standalone, traditional WebEx video or the new HQ video-featured WebEx site. One Mbps send/receive is a minimum requirement per single meeting. A single meeting may contain more than one Cisco TelePresence system, but this scenario does not increase the bandwidth usage for that meeting. Multiply the minimum 1 Mbps by the number of expected simultaneous meetings.

Presentation video (desktop sharing) uses approximately 400 kbps with 500 kbps maximum.

The maximum download needed for Common Interchange Format (CIF) video is variable, with the encoder rate limited to a maximum of 500 kbps between the Cisco TelePresence Management Suite and Cisco TelePresence Gateway and the receiving WebEx client.

Table 11 gives the WebEx client average bandwidth used with Cisco WebEx and CMR integration.

Table 12 outlines the bandwidth requirements for the WebEx client in CMRs.

Table 11.     WebEx Client Average Bandwidth Used with Cisco WebEx and CMR Integration

Bandwidth and CPU power: Recommendation for good video quality and integration of the Cisco CMR network with Cisco WebEx

Network bandwidth should be at least 1 Mbps upstream between the infrastructure and

WebEx CMR Gateway per call. For example, if you are anticipating five simultaneous

Cisco WebEx calls you will need to have five 1-Mbps bandwidth instances.

Suggested CPU power (depends on running applications) is dual core CPU, 2.5-GHz memory running at least 2 Gbps.

Cisco WebEx client resource requirements: Expected resource allocation per meeting

Users must have at least 850k of available resources per meeting to uplink to Cisco WebEx:

  CIF video: 300k down only
  Presentation video: 450,000 up and down (depending on whether the client is performing or receiving a presentation)
  Cisco WebEx video: 400,000 up; 400,000 x N down, where N is the number of streams the user chooses to view
  Cisco WebEx VoIP: Up and down (70,000~150,000) bps
  Signaling: 100,000

Table 12.     Bandwidth Requirements for WebEx Client in CMR

Main Video as Seen by WebEx Client

Data Sharing as Seen by WebEx Client

Bitrate per WebEx Client

Notes

HD/720p

1080p* (with conductor, CMR-Hybrid only)

~3.0 Mbps

CMR-Hybrid only. Conductor required. Source of presentation must be 1080p(16:9)

HD/720p

720p

~2.5 Mbps

Source of presentation must be sharing at least 720p(16:9), highest level for CMR-Cloud

HD/720p

XGA

~2.0 Mbps

 

360p

XGA

~1.5 Mbps

 

180p

XGA

~1.2 Mbps

Lowest level for the WebEx Client to receive main video

None

XGA

~0.5 Mbps

Dropped from main video channel (will retest to re-enter)

*Desktop WebEx Client scale (PC and Mac)

Network Traffic Summary for Data Presentation on Mobile Devices

Table 13 gives test results for the iPhone 4 (16 Gb) and BlackBerry Bold 9700 over a third-generation (3G) network.

Table 13.     Results for iPhone 4 (16 Gb) and BlackBerry Bold 9700 over 3G Network

 

Traffic (Test Scenario)

Average (kbps)

Maximum (kbps)

iPhone

Idle meeting

0.17

0.28

BB

0.26

0.33

iPhone

Desktop share (slide presentation with 30-second transitions)

23

41

BB

2.87

3.08

iPhone

Presentation share (slide presentation with 5-second transitions)

14.5

17

BB

5.73

6.4

Note:    The iPhone and iPad devices use vector graphic technology, which provides better image quality for viewing the shared content, and therefore requires more bandwidth compared to imaging technology used with the other mobile devices.

Table 14 gives test results for the iPhone 3G, Blackberry Bold 9700, and iPad (16 Gb) with a Wi-Fi network.

Table 14.     Results for iPhone 3G, Blackberry Bold 9700, and iPad (16 Gb) with Wi-Fi Network

 

Traffic (Test Scenario)

Average (kbps)

Maximum (kbps)

PC

Idle meeting

0.8

3.7

iPhone

0.17

0.4

iPad

8.9

9

BB

0.42

0.45

PC

Desktop share (slide presentation with 30-second transitions)

43

598

iPhone

67

232

iPad

95

241

BB

24.8

29.92

PC

Presentation share (slide presentation with 5-second transitions)

6.5

7.5

iPhone

23

41

iPad

30

62

BB

54.56

55.28

Network Traffic Data Comparison Chart

Tables 15 and 16 compare network traffic data from the tests for the iPhone 3G, iPad (16 Gb), and BlackBerry Bold 9700 with a Wi-Fi network.

Table 15.     Comparison of Results at Idle

Idle

 

Average (kbps)

Maximum (kbps)

PC

0.8

3.7

iPhone 3G

0.17

0.4

iPad 16 Gb

8.9

9

BB

0.42

0.45

Table 16.     Comparison of Results During Presentation Sharing

Presentation Share (Slide Presentation with 5-Second Transitions)

 

Average (kbps)

Maximum (kbps)

PC

6.5

7.5

iPhone 3G

23

41

iPad 16 Gb

30

62

BB

54.56

55.28

Table 17 gives test results for the iPhone 4 (16 Gb) and BlackBerry Bold 9700 with a 3G Network. Table 18 shows the amount of data consumed in one hour over 3G/4G LTE networks.

Table 17.     iPhone 4 (16G) and BlackBerry Bold 9700 with 3G Network

Idle

 

Average (kbps)

Maximum (kbps)

iPhone

0.17

0.28

BB

0.26

0.33

Table 18.     Data consumed over 3G/4G LTE Networks

Data Consumed in an Hour

Audio using Internet (VoIP)

~23 MB

Video (at 90p)

~43 MB*

ViewcContent (flip PDF page rapidly)

~250 MB

Total per hour

~316 MB

* Bandwidth consumption will increase if the SuperAdmin setting “frame rate increase” is enabled.

Common Problems and Location of Log Files

Factors affecting the video quality include:

   WebEx site, host, and meeting settings. For example, a video setting set by the administrator or host for a specific meeting may not allow HQ video at the 360p resolution.

   PC capabilities. For example, a non-dual core with insufficient memory cannot process the 360p video resolution and you will experience lower-quality video (both encode and decode).

   Camera capabilities. For example, certain cameras can compensate for the low-light environment, some have auto-focus, and others work in HD and require more CPU power.

   In-room lighting or backlight background.

   Measured bit rate. Not enough bandwidth available for the client PC automatically reduces the video quality and frame rate from 720p to 360p to 180p resolution or disables the video.

   Video mode and display size. A 180p receiving resolution will not achieve the same video quality experience in the full-screen (HQ) or expanded full-screen (HD) video mode as the 360p or 720p resolution.

The displayed video size is what you will see in the theater mode. Depending on the resolution of the monitor used, the displayed video can be scaled up and enlarged to fit the monitor screen. This video size is independent of the resolution of the incoming video source.

If the highest quality of video that “user1” can send is 180p, based on PC hardware and available bandwidth, then 180p is the highest video resolution that a remote site “user2” can receive. This resolution refers to the video resolution after the decoding process for “user2”. If the source of the incoming video is 180p, it is impossible for the decoder on the “user2” PC to output any resolutions higher than 180p.

During application sharing, desktop sharing, streaming video sharing, and meeting manager sharing, 720p video (HD) is disabled.

A quad-core PC or Mac can send and receive 720p (HD) resolution; a dual-core PC or Mac can receive only 720p (HD) in multipoint meetings (includes three or more participants).

Because of network congestion or client machine use, the video stream may wait to be sent or received. During this time you may have a visible, small-circle icon in the middle of your main video window; it will disappear as soon as the video stream becomes available.

The log files can help administrators and support teams to better understand and troubleshoot possible client software problems. Location of the log files is shown Table 19.

Table 19.     Location of Log Files

Platform

Location

Windows XP

C:\Documents and Settings\&username&\Local Settings\Temp\Webex\Wbx_AudioVideoStatisticsData.csv

Windows 7

C:\Users\&username&\AppData\Local\Temp\WebEx\Wbx_AudioVideoStatisticsData.csv

Windows 8

C:\Users\&username&\AppData\Local\Temp\WebEx\Wbx_AudioVideoStatisticsData.csv

Maximum size of the log file is 5 MB. When the maximum size is reached, the oldest data is overwritten by the new data. Other platforms will be available in future releases.

Video Statistics Window

WebEx Meeting Center features a real-time audio and video statistics window. The window includes a summary of the current audio and video usage status such as:

   Audio and video latency in milliseconds (ms)

   Audio and video jitter in ms

   Audio and video packet-loss percent

   Video resolution

   Video fps

   Number of video streams received

   Video codec type

   Audio codec type

   Overall WebEx CPU usage percent

   Overall memory CPU usage percent

   Connection ports

   Internet Protocol used by audio and video

Figure 10 provides an example of the statistics window. During a WebEx meeting, you can right-click on the main video window and select statistics.

Figure 10.   Statistics Window

Summary

WebEx services can reduce the amount of data transmitted over the network. The WebEx client transmits data only when data is requested. During most of a meeting, the content is static and no data is transmitted, keeping network traffic to a minimum. When there is activity in a meeting, such as loading a presentation, changing a slide, or sharing an application, data transfer lasts for only short periods of time, and only parts of the screen change. This includes presentation sharing, desktop sharing, and live video.

This type of behavior produces inconsistent streams of network traffic, causing the traffic to remain at a
below- average point for most of the time, with occasional spikes to a maximum value. In a typical desktop-sharing meeting, the bandwidth requirements are usually low and have no major impact on the network.

For More Information

For more information about Cisco WebEx network bandwidth and Cisco WebEx products, visit these additional online resources:

   Cisco Conferencing Products: http://www.cisco.com/go/webex

   Cisco WebEx Knowledge Base: http://kb.webex.com

   Cisco WebEx Support: http://support.webex.com