I CAN SEE CLEARLY NOW… - Adventiq – home · i can see clearly now… t h e f a c t s a bo u t k v m o v e r i p , b a n d w i d t h a n d v i d e o executive summary not all keyboard

V5.1 Copyright © Adventiq Ltd. April 2007 Page | 1

I C AN S EE C LE AR LY N OW …

T H E F A C T S A B O U T K V M O V E R I P , B A N D W I D T H A N D V I D E O

EXECUTIVE SUMMARY

Not all keyboard-video-mouse (KVM) systems are the same. Their complexity,

functionality, and in particular their performance can differ considerably from one

system to another. This presents a challenge to those responsible for specifying

KVM solutions for use on corporate networks. It’s also a challenge for those tasked

with designing the next generation of KVM-over-IP equipment. Both must consider

issues that if overlooked could lead to poor performance – not just poor

performance of the KVM system itself but of the corporate network as a whole.


This paper discusses the performance measurements of KVM control systems and in particular those systems that use IP networks for distribution – so-called “KVM-over-IP” systems. We examine some metrics that can be applied to KVM-over-IP systems, and introduce Adventiq’s ARQ3 KVM-over-IP System-on-Chip (SoC). We give detailed performance results for an ARQ3-based system. These can be compared against publicly-available performance data for an alternative KVM-over-IP system. Finally, we conclude with a note outlining the benefits of using an SoC solution in the implementation of KVM-over-IP solutions.

INTRODUCTION – WHY KVM IS IMPORTANT

The demand that companies place on their computer server infrastructure continues to increase at an unerring pace. Gartner recently reported that server shipments in 2006 were up 8.9% on the previous year - creating a market, for servers alone, of nearly USD$52bn1. This increase is significantly higher than other areas of IT spend – total IT budgets grew by less than 6% in the same period. With this scale, and pace of growth, the system administrator’s task of ensuring system availability at all times is an unenviable one. The complexity of a typical corporation’s network – the number and variety of servers, the location of these servers, their security requirements and quality-of-service demands – are constantly increasing. Yet the CIO or IT manager must manage this network to a higher degree of reliability, and on an ever-constrained budget.

One tool available to the IT manager – and end user alike – is a Keyboard-Video-Mouse remote access system (“KVM”). With KVM, the IT manager can be freed to control systems and servers from any location that is appropriately connected. KVM is fundamental to many tasks in system management, maintenance and deployment.

Unlike other systems administration tools, a good KVM system can be used regardless of the state of health of the machine that it is monitoring. With this BIOS-level maintenance capability, operating system re-configurations, or even locked-up or crashed machines can be tackled without the need to “ship live bodies to dead servers”. Furthermore, KVM and particularly KVM-over-IP, enables the integration of monitoring and control tasks with other management procedures – inventory, audit and software provisioning, for example.

1 Gartner worldwide server shipment report, February 2007. Available from www.gartner.com


FEATURES OF A KVM-OVER-IP SOLUTION

REMOTE CONTROL. The operation of a KVM-over-IP system is quite simple. Figure 1 shows the typical configuration of a KVM-enabled IP network. At the server or “host” end, a KVM device must receive video and console output from the host computer, encrypt and compress this information as appropriate, and ship it to the remote end (the ‘viewer’) for decryption, decompression and rendering on a display. In the other direction, sources of system input – keyboard, mouse or other kinds of input – are transferred from the remote end to the host and are made to appear as if these input sources are being provided to the host by a local operator - as if he were sitting right in front of the host computer.

FIGURE 1 - A TYPICAL KVM-OVER-IP ENABLED NETWORK

VIRTUAL MEDIA It’s particularly useful for a KVM system to be able to present a filesystem as a remote input source to a KVM-enabled host. This so-called “Virtual Media” capability (exporting floppy drive, CD-ROM, file system and potentially other kinds of peripherals across the network) is now an integral requirement for a KVM-over-IP system. Virtual Media capabilities enable the operator to deploy new software, reconfigure, patch and upgrade systems in an efficient manner from anywhere that he has access to the network.

SECURITY The security policies adopted by a KVM system are a principal consideration when planning its deployment. Without the most robust and stringent security in place, a KVM system introduces new means by which the integrity of a corporate network could be compromised. However, if the right KVM


system is deployed in the right way, it can in fact increase the security of a company’s computing infrastructure. A KVM system makes it possible for servers to be

physically located anywhere, and in particular these servers can be located in a more secure environment. Physical access to these servers can be more heavily restricted when a KVM system is employed. KVM systems also enable systems of multiple redundant servers to be managed more efficiently. But in a KVM system, security mechanisms must be implemented carefully. It is important that any security techniques employed do not introduce an unacceptable overhead in processing time or network utilization.

PERFORMANCE IS IMPORTANT

It has been suggested that introducing KVM-over-IP systems onto a corporate network can increase the network’s loading to a potentially unacceptable level. The increase comes about because of the additional network traffic created by shipping the display image of any number of servers across the same network as normal corporate data. This issue must be considered in both the design and deployment of a KVM-over-IP system.

It is also important that KVM systems can operate acceptably across very poor networks. Any IT manager who has had to fix a server from a remote location with only a mobile-phone connection to hand will testify to this. So, it is important to understand the typical loading that a particular KVM-over-IP system will place on the network, as well as considering the usability of the system under a variety of different network conditions.

We need to design the protocols used by a KVM-over-IP system so that they do a good job of rendering the contents of a display to a remote site, whilst not taking up, or assuming the availability of, too much bandwidth.

MEASURING PERFORMANCE

Ensuring good performance across a variety of network conditions is just one reason for measuring the performance of a KVM-over-IP system. We are interested in the efficiency with which it does its work, the efficiency with which the communications medium is used, and how useful or useable is the output of that work.

“KVM solutions … can increase the security of

a company’s computing infrastructure.”


Ultimately some of the measurement of the performance of a KVM system will always be subjective. It’s about how responsive the system is – how useable it feels – these things can be quite difficult to quantify. In this paper we will focus on the network utilization of a KVM-over-IP system, as this is a key measure that is easy to quantify.

INTRODUCING THE ARQ3

Adventiq has pioneered the efficient implementation of KVM-over-IP as a System on Chip (SoC). Adventiq’s latest product - the ARQ3 – combines the maturity of a third-generation KVM-over-IP solution with the performance enhancements and simplicity of an SoC. ARQ3 consists of an embedded ARM-compatible processor, some dedicated logic for video processing and security and some on-board memory as well as a collection of USB, PS/2 and Ethernet interfaces.

ARQ3 supports digital and analog video sources, PS/2 and USB keyboard and mouse, has USB support for Virtual Media as well as hardware accelerators for security encryption and video processing. It has been designed to make the task of building a next-generation KVM-over-IP system much simpler.

ARQ3 has a good pedigree – it embeds a remote system server pioneered by RealVNC of Cambridge, England. RealVNC has grown to become the de facto standard in remote desktop protocols and provides flexibility and efficiency that are unparalleled. Adventiq is the first and only company to incorporate a RealVNC server into an SoC.

THE ARQ3 ADVANTAGE – ADAPTIVE PROTOCOLS

The advantage that the design of the ARQ3 brings to KVM-over-IP lies in the adaptive protocols that it uses to ship KVM information across the network. ARQ3 uses enhanced RealVNC server protocols that can efficiently adapt to a variety of differing network conditions. When there is sufficient bandwidth available, the ARQ3 will use simpler compression techniques to minimize latency and improve the user experience. When network bandwidth is at a premium, the ARQ3 can adapt the compression adopted to suit the circumstances. The three main compression techniques used by the ARQ3 are called “Raw”, “Hextile” and “ZRLE”. Each of these protocols is described in detail in [1].

The result of these adaptive compression protocols is that an ARQ3 system will always maintain an optimum trade-off between use of bandwidth and KVM


performance, resulting in the best possible user experience in a wide variety of circumstances.

NETWORK UTILIZATION AND PERFORMANCE OF THE ARQ3

So, how does the ARQ3 measure up ? We performed five tests to get a feel for the ARQ3’s performance, and to see how it compares with competing solutions. The five tests are described in detail in [2]. We present the results of our performance tests – these can be compared with the results outlined in [2].

For the ARQ3 we have tested the system with each of the three compression techniques – Raw, Hextile and ZRLE. In a real system, the ARQ3 would always use the most appropriate compression technique depending on the condition of the network. We also performed the tests under a variety of video modes and color modes to see the effect that these have on overall performance.

SYSTEM SET-UP

For our experiments we used a system configuration outlined in Figure 2. Our “Host” computer was a PC running Windows XP2, and local access and control was via a terminal on the same segment of a 100Mbps LAN. The KVM device was a prototype KVM unit using the Adventiq ARQ3 SoC.

FIGURE 2- SYSTEM SET UP FOR TESTING

2 Microsoft , Windows and Windows XP are trademarks of Microsoft corporation


TEST 1 – CONTINUOUS MOUSE MOVEMENT

In this test, we move the mouse around a static Windows desktop screen as quickly as possible for a period of two minutes. We record the number of frame updates that are issued (as an “average frames per second”), and the uplink and downlink bandwidth used by the system to transmit these frames across the network. Full details of the results of this test are given in Appendix 1.

With the most efficient encoding for this task, the ARQ3 (with a screen resolution of 1024x768 and 15-bit color depth) uses just 4 kbit/s of downlink and 6 kbit/s of uplink traffic to achieve a frame-rate of just under 29 frames per second.

Device Video Mode

Colour Mode Encoding

Frames Per

Second

Average downlink bandwidth (Mbits/s)

host to client

Adventiq ARQ3

1024x768

15-bit

Raw 29.0 0.372

Hextile 29.0 0.015

ZRLE 28.4 0.004

8-bit

Raw 21.5 0.186

Hextile 28.8 0.009

ZRLE 29.8 0.003 TEST 1 – CONTINUOUS MOUSE MOVEMENT


TEST 2 – NAVIGATING TEXT FILES

This test is designed to simulate a typical administration activity – navigating and editing some text files with a variety of different editors (Microsoft Notepad, Microsoft Word and emacs). The test was conducted using a pre-recorded full-screen “session” of text editing activities3. This session was replayed at various screen resolutions and color modes for each of the different measurements made in this test. The competing solution used a very similar technique to perform this test, although a different “session” was used.

We can see that overall the bandwidth consumed by the ARQ3 is relatively low. For example, in the case of a 1024x768 image being rendered with 15 bits of color, the ARQ3 consumes just 764Kbits/S.

Device Video Mode

Colour Mode

Encoding

Average downlink bandwidth (Mbits/s)

host to client

Adventiq ARQ3

640x480

15-bit

Hextile 0.660

Raw 0.722

ZRLE 0.702

8-bit

Hextile 0.411

Raw 0.445

ZRLE 0.422

1024x768

15-bit

Hextile 0.764

Raw 0.884

ZRLE 0.868

8-bit

Hextile 0.585

Raw 0.614

ZRLE 0.602

TEST 2 – NAVIGATING TEXT FILES

3 We created these pre-recorded sessions using the application MediaCam from netu2, www.netu2.com. This technique ensured that the very same video data was encoded by the ARQ3 for each test.


TEST 3 – WINDOWS REBOOT

In this test, we reboot the host PC (running Windows XP). Throughout the period of reboot we record the number of frame updates that are issued (as an “average frames per second”), and the bandwidth used by the system to ship these frames across the network. The results are outlined here.

Device Video Mode


Average downlink

bandwidth (Mbits/s) host to

client

ARQ3

1024x768

15-bit

Raw 0.757

Hextile 0.022

ZRLE 0.009

6-bit

Raw 0.458

Hextile 0.013

ZRLE 0.006

640x480

15-bit

Raw 0.682

Hextile 0.024

ZRLE 0.007

6-bit

Raw 0.347

Hextile 0.010

ZRLE 0.004 TEST 3 – WINDOWS REBOOT


TEST 4 – WEB BROWSING

This test recreates another typical system administration task – browsing websites. For this test we browsed content from a variety of media-rich web-sites including www.foxnews.com, www.weather.com and www.msn.com. The test, similar to Test 2, was conducted using a pre-recorded full-screen “session”. This technique ensured that the very same video data were encoded by the ARQ3 for each test

The results of this test are outlined here. It is worth noting that in the case of 1024x768 display size and 15-bit colordepth, the ARQ3 consumes just 680Kbits/S with the Hextile encoding.

Device Video Mode


Average downlink


client

Adventiq ARQ3

1024x768

15-bit

Raw 0.744

Hextile 0.680

ZRLE 0.502

6-bit

Raw 0.455

Hextile 0.376

ZRLE 0.280

640x480

15-bit

Raw 0.520

Hextile 0.469

ZRLE 0.310

6-bit

Raw 1.031

Hextile 0.311

ZRLE 0.341 TEST 4 –WEB BROWSING


TEST 5 – QUICKTIME MOVIE TRAILER

In the last of our comparative tests, we experimented with video playback. We chose the same video trailer in all experiments – a movie trailer that has a size of 640x240 pixels4. We record the average frames per second that can be achieved, and the average bandwidth consumed to achieve that number of frames per second. Then, we compute the “frames per second per mega-bit per second (“FpS/MpS”)” which gives us a measure of the efficiency of the compression used.

When playing video, other systems can deliver a higher framerate than the ARQ3. But there is a price to be paid for this higher framerate – in some systems an average bandwidth of over 4 Mb/s. In designing the protocols adopted by ARQ3 we considered that bandwidth consumption of this level was not desirable for a KVM system. The competing solution sees a best-case of 4.44 frames-per-second-per-megabit-per-second. The ARQ3 can consistently achieve much higher network efficiency than this. The ARQ3 results are consistent with a system that has been designed to make optimum use of the network bandwidth available, without compromising the other traffic on the same network. Most would agree that this is more appropriate behavior for a KVM-over-IP system.

The full results of this test are outlined here.

Device Video Mode


Average downlink


client

Adventiq ARQ3

1024x768

6-bit

Raw 0.347

Hextile 0.010

ZRLE 0.002

15-bit

Raw 0.757

Hextile 0.022

ZRLE 0.007

640x480

6-bit

Raw 0.458

Hextile 0.013

ZRLE 0.006

15-bit

Raw 0.682

Hextile 0.024

ZRLE 0.007 TEST 5 - QUICKTIME MOVIE TRAILER

4 The Good, The Bad, and the Ugly – available from http://uk.rottentomatoes.com/m/good_the_bad_and_the_ugly/trailers.php


FURTHER TESTS – THE PERFORMANCE OF VIRTUAL MEDIA

Adventiq believes that the performance of the virtual media functions of a KVM-over-IP system can also have a big impact. Poorly-designed virtual media capabilities can be at best frustrating to use and at worst unusable. We cover performance measurements of virtual media in a forthcoming whitepaper.

CONCLUSIONS AND SUMMARY

We have seen that the performance and network utilization of KVM-over-IP systems can vary considerably. Systems need to be designed with care, taking into account the typical conditions of the network on which they will run, as well as the kind of application usage to which they will be put.

KVM-OVER-IP BANDWIDTH REQUIREMENTS TESTS – SUMMARY OF RESULTS

The tasks of a KVM-over-IP system lend themselves very nicely to integration into an SoC. A dedicated piece of silicon to perform all of the tasks outlined earlier means that equipment manufacturers can get to market quickly and can focus on differentiating the products that they building in other ways. To the end customer, an SoC solution will mean more reliability, lower power, and lower end cost.

0.022

0.764

0.022

0.680

2.050

0.708

0.000

0.500

1.000

1.500

2.000

2.500

Test 1Mouse

movement

Test 2Text Editing

Test 3Windows Reboot

Test 4Web

Browsing

Test 5Movie

Tests 1-5Average

Ba

nw

idth

use

d (M

bp

s)

Adventiq ARQ3 performance tests


Adventiq’s ARQ3 device has been shown to perform well under a variety of usage scenarios – the adaptive protocols make best use of the available network without compromising the use of that network by normal traffic. We are confident that introducing an efficient SoC solution for KVM-over-IP devices will soon change the way that all such devices are made.

REFERENCES

1. The RFB Protocol. Richardson, T. http://www.realvnc.com/docs/rfbproto.pdf

2. Are You Getting a True Picture? The Facts About KVM over IP, Bandwidth and Video. Avocent inc. http://www.global.avocent.com/openlead/?ID=videobandwidthwp

ABOUT ADVENTIQ LTD.

Computer peripheral manufacturers are using Adventiq’s ingenious system-on-chip and software building blocks to create the next generation of IP-enabled remote access and digital extension products. Based in Cambridge, England, Adventiq is a privately held company. Find out more at www.adventiq.com.

COPYRIGHT INFORMATION

This document contains proprietary information that is protected by copyright. All rights reserved. No part of this document may be photocopied, reproduced, or translated into another language without express prior written consent of Adventiq Ltd.

Adventiq Limited - Technology House, Trafalgar Way, Bar Hill, Cambridge CB3 8SQ, England Tel: +44 (0) 870 890 3881 Fax: +44 (0) 870 890 3882

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I CAN SEE CLEARLY NOW… - Adventiq – home · i can see clearly now… t h e f a c t s a bo u t k v m o v e r i p , b a n d w i d t h a n d v i d e o executive summary not all keyboard