Xendesktop Planning Guide User Bandwidth Requirements

XenDesktop Planning Guide: User Bandwidth Requirements

Written by Dennis van DamMonday, 09 August 2010 20:55 - Last Updated Monday, 09 August 2010 20:57

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XenDesktop Planning Guide:

User Bandwidth Requirements

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Overview

Regardless of the flavor of virtual desktop being implemented (hosted shared, hostedVM-based VDI, local streamed, etc.), the network plays a critical role, especially for remote andbranch office users. If the network bandwidth is not planned properly, users will most likelyexperience poor performance with their virtual desktop.

When planning a virtual desktop solution, one must

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XenDesktop Planning Guide:

User Bandwidth Requirements

Overview

Regardless of the flavor of virtual desktop being implemented (hosted shared, hostedVM-based VDI, local streamed, etc.), the network plays a critical role, especially for remote andbranch office users. If the network bandwidth is not planned properly, users will most likelyexperience poor performance with their virtual desktop.

When planning a virtual desktop solution, one must think about how the user’s workload willevolve. The design must be able to support future activities, not just today’s. As can beobserved, the content users interact with is changing from textual-based to moremultimedia-based. Any solution and methodology must be able to account for these changes inuser behavior. Although there is no single answer to the question of how much bandwidth will auser need, this planning guide provides recommendations on how to estimate the user network requirements.

This guide is used to provide bandwidth estimates during the planning and design phase.Actual results may vary during implementation due to user habits, bandwidth utilization, andinfrastructure implementation.

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This methodology provides an average bandwidth estimate. Different activities will result in aburst of traffic (video and printing). It is assumed traffic bursts will be random between usersthroughout the workday. If all users have network bursts at the same time, performance willdegrade as adequate bandwidth levels will not be available.

The bandwidth estimates were obtained through the testing procedures identified in theCTX124457 – Performance Assessment and Bandwidth Analysis for Delivering XenDesktop toBranch Offices white paper. Additional modifications, as explained in CTX125060 - BestPractices for Optimizing HDX Technologies white paper, can be used to further reducebandwidth consumption at the cost of the user experience.

Guidelines

As one would expect, the user experience can degrade as the latency increases and thebandwidth decreases. Proper network planning must be based on the type of work users areperforming and the overall network topology. The bandwidth requirements of delivering a fullWindows desktop will likely be higher than the bandwidth required for delivering fewapplications using a solution like XenApp because a full Windows desktop provides a richer

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experience along with more multimedia and graphical content and is idle less often than whena user is only accessing few applications.

Estimating network requirements needs planning and following best practices because CitrixHDX technology tunes itself based on several factors including the servers, end points and theamount of network bandwidth available. For example, if less bandwidth is available then morecompression is applied.

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Also, to better determine user bandwidth requirements, the user’s activity must be assessed.Simply estimating bandwidth for Office-based applications will result in inadequate performanceif users also print and access multimedia content. The percentage of time a user spendsworking with Office-based applications, browsing the Internet, accessing videos, and being idlewill help in determining the overall bandwidth required.

Planning

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By calculating the percentage of time a user is expected to be doing certain activities, a rough estimate can be determined for HDX bandwidth requirements, which is shown in the follow table: Parameter (medium workloads)

Native XenDesktop

XenDesktop with Branch Repeater

Office-based 43 kbps 31 kbps Internet 85 kbps 38 kbps Printing 555-593 kbps 155-180 kbps

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Flash Video 174 kbps 128 kbps Standard WMV Video 464 kbps 148 kbps High Definition WMV Video 1812 kbps 206 kbps Idle

Based on active applications

Based on active applications

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Note

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: These are estimates. If a user watches a WMV HD video with a bit rate of 6.5 Mbps, that userwill require a network link with at least that much bandwidth. In addition to the WMV video, thelink must also be able to support the other user activities happening at the same time. Whenthe user group is small, it is easy for calculations based on averages to come out short of theactual required pipe size.

An interesting point with regards to bandwidth usage is during idle time. If the user is idle butthe applications are still active, chances are that there is still a bandwidth element to consider.Many applications (Outlook, Internet browsers, etc) continue to update the screen throughconstant updates and synchronization. These will in turn impact the overall bandwidth usage.

Also, if multiple users are expected to be accessing the same type of content (videos, webpages, documents, etc.), integrating the Branch Repeater into the architecture can drasticallyreduce the amount of bandwidth consumed. However, the amount of benefit is based on thelevel of repetition between users.

Note

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: Additional details on the bandwidth estimates can be gathered by referring to the followingCitrix white paper: CTX124457 – Performance Assessment and Bandwidth Analysis forDelivering XenDesktop to Branch Offices.

By using this information, the following formula can be used to estimate the bandwidthrequirements for a group of active users with similar workloads:

Estimated Bandwith:

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Based on the formula, the following scenario is used to help calculate the average networkconsumption for a typical 8AM to 5PM workday.

Office-based: 4 hours

Internet: 1 hour

Printing: 15 minutes

Flash Video: 30 minutes

Standard WMV Video: 10 minutes

HD WMV Video: 5 minutes

Idle: 3 hours (one hour lunch and two, one hour meetings)

1

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1 The bandwidth usage for idle sessions is not being calculated as part of the formula. It isoften recommended to lock the desktop and enable a screen saver after a short period of idletime. To conserve bandwidth, the selected screen saver is to blank the screen, thus notconsuming additional bandwidth.

2 Assuming the burst is coming from the user watching High-Definition WMV videos. For owncalculations, utilize the activity that has the largest bandwidth consumption.

For an entire day, a particular user in this scenario would require roughly Average Burst Native XenDesktop 78 kbps

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1812 kbps2 XenDesktop with Branch Repeater

34 kbps

206 kbps

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1 The bandwidth usage for idle sessions is not being calculated as part of the formula. It isoften recommended to lock the desktop and enable a screen saver after a short period of idletime. To conserve bandwidth, the selected screen saver is to blank the screen, thus notconsuming additional bandwidth.

2 Assuming the burst is coming from the user watching High-Definition WMV videos. For owncalculations, utilize the activity that has the largest bandwidth consumption.

Caution must be taken when using the average value. By averaging out the bandwidthrequirements across an entire day and across many users, there may be a lack of bandwidth ifa large percentage of users have a large burst in traffic at the same time. Based on theexpected user habits, it is advisable to include a bandwidth burst calculation for unexpectedbursts of traffic.

Note

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: Branch Repeater bandwidth estimates assume users are watching and accessing similarcontent. If the content is different, the bandwidth savings will not be nearly as great.

For certain environments, additional modifications to XenDesktop and HDX can beimplemented to try and reduce the bandwidth requirements even further. Many of thesemodifications reduce bandwidth by slightly degrading the user experience. The estimates usedin this document were based on mostly default configurations. By utilizing additionalfunctionality, like the following, the bandwidth requirements can be reduced further:

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* More aggressive HDX compression

* Bandwidth limitations on HDX virtual channels

* Reduction in the video rendering frame rates

A more complete list of bandwidth tuning tips can be found by leveraging the CTX125060 -Best Practices for Optimizing HDX Technologies white paper.

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Xendesktop Planning Guide User Bandwidth Requirements

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