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PCoIP Technology User Guide (Vol I)

9 Latency Considerations

With any network, there are latency effects to be

addressed. The following are latency effect

considerations for PCoIP Technology

deployments:

• Latency effects are subjective and affect

response (e.g. mouse movement)

• Latency due to length of physical medium (i.e.

speed of light of copper/fiber) and switch hops

• Additional latency due to OS (e.g. 40-50 ms

for Windows)

The table below outlines latency effects

examples based on critical user evaluation. User

tolerance levels for latency vary widely.

Table 2: Latency

Network

Approx. Distance

Latency

0-30 ms

Campus/Metro/

Inter-city

(0-1500 km)

40-60 ms

Inter-city/Intra-

country

(1500-2500 km)

60-100 ms

Intra-country/ Inter-

continent

(2500-5000 km)

> 100 ms

Inter-continent/

Overseas

(> 5000 km)

Notes

1. High bandwidth, low error network

2. Examples given are based on subjective

critical analysis

Note: As with bandwidth considerations, these

latency observations are subjective and biased

towards a perception free experience.

Administrators must study use case(s) typical for

their deployment and adjust user expectations

accordingly.

Example

Observations

Perception free to

average user

Minimal latency

perceived, e.g.

'heavier' than usual

mouse

pointer/windows,

but very usable

Sluggish mouse

and windows

Some audio/ video

dropouts

Slow mouse and

windows

Audio/video

dropouts

TER0806003 Issue 1

Desired Network Attributes

The desired network attributes to minimize

latency effects are:

• High bandwidth

• Low error rate

• Minimized data path/network hops

Networks with less desirable network attributes

will result in decreased performance, i.e.

decreased mouse and display responsiveness.

USB Latency Performance

USB performance can vary over latency for the

various transfer types:

• Isochronous – may notice delay or loss of data

(e.g. video data lost on a webcam)

• Interrupt – may delay device response (e.g.

slow keystrokes from keyboard)

• Bulk – may notice slower data transfer (e.g.

slower USB FLASH drive)

Minimizing Latency Effects

The following are suggestions for extreme long

distances, non-enterprise networks or less than

desirable networks to minimize latency effects:

• Use graphically less demanding computer

applications and set user expectations

accordingly

• For bandwidth constricted environments,

configure Device Target Bandwidth and

Device Bandwidth Limit parameters to limit

bandwidth usage to minimum required (see

Section 6 Bandwidth Considerations)

• Configure Image settings to minimum image

quality required (see Section 7 Imaging

Considerations).

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