HP mt245 Technology Overview - Page 5

LiveQ

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Technology Overview | HP Velocity LiveQ Packet loss occurs when packets traversing a network do not reach their destination. A number of factors contribute to packet loss, including signal degradation over the network, network congestion, corrupted packets, and hardware issues. In UDP-based transport, which does not guarantee packet delivery, even a small amount of packet loss can cause applications to slow down or reduce the bit rate. This results in digital artifacts, smeared video, broken and choppy audio, or low frame rate in applications such as PCoIP, RDP, VP8, SIP, VoIP, and video. LiveQ outputs the original number of input packets as well as extra packets containing redundancy information. The number of packets that are used to encode the redundant packets and the number of redundant packets generated varies based on current network-loss conditions and the configured Target Loss Rate. Figure 2:LiveQ transformation of packets Target loss rate Different applications tolerate different levels of packet loss. Some applications perform poorly with a small amount of packet loss while other applications perform satisfactorily even with significant amounts of packet loss. HP Velocity adjusts its operation to ensure that each application is protected from experiencing too much packet loss. The target loss rate (TLR) is the amount of loss that an application can tolerate while still delivering an acceptable QoE. The recommended TLR for thin-client applications is 0.04%. Encoding modes The encoding modes determine the amount of redundancy added to an application flow. HP Velocity automatically adapts the encoding mode for a flow according to the configured TLR and current network conditions. The values in Table 1 show how HP Velocity adapts the LiveQ encoding mode to keep the corrected loss level below a TLR of 0.04% for an application flow with a bit rate higher than 1 Mb/s. Table 1: LiveQ encoding Network Loss (%) Redundancy (%) 0.04 - 0.8 10 0.8 - 1 20 1 - 1.8 30 1.8 - 2.8 40 2.8 - 3.9 50 3.9 - 5.9 60 5.9 - 6.2 70 6.2 - 7.9 80 7.9 - 8.8 90 8.8+ 100 3

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Technology Overview
|
HP Velocity
LiveQ
Packet loss occurs when packets traversing a network do not reach their destination. A number of factors contribute to
packet loss, including signal degradation over the network, network congestion, corrupted packets, and hardware issues.
In UDP-based transport, which does not guarantee packet delivery, even a small amount of packet loss can cause
applications to slow down or reduce the bit rate. This results in digital artifacts, smeared video, broken and choppy audio,
or low frame rate in applications such as PCoIP, RDP, VP8, SIP, VoIP, and video.
LiveQ outputs the original number of input packets as well as extra packets containing redundancy information. The
number of packets that are used to encode the redundant packets and the number of redundant packets generated
varies based on current network-loss conditions and the configured Target Loss Rate.
Figure 2:LiveQ transformation of packets
Target loss rate
Different applications tolerate different levels of packet loss. Some applications perform poorly with a small amount of
packet loss while other applications perform satisfactorily even with significant amounts of packet loss. HP Velocity
adjusts its operation to ensure that each application is protected from experiencing too much packet loss.
The target loss rate (TLR) is the amount of loss that an application can tolerate while still delivering an acceptable QoE.
The recommended TLR for thin-client applications is 0.04%.
Encoding modes
The encoding modes determine the amount of redundancy added to an application flow. HP Velocity automatically
adapts the encoding mode for a flow according to the configured TLR and current network conditions.
The values in
Table 1
show how HP Velocity adapts the LiveQ encoding mode to keep the corrected loss level below a
TLR of 0.04% for an application flow with a bit rate higher than 1 Mb/s.
Table 1:LiveQ encoding
Network Loss (%)
Redundancy (%)
0.04 - 0.8
10
0.8 - 1
20
1 - 1.8
30
1.8 - 2.8
40
2.8 - 3.9
50
3.9 - 5.9
60
5.9 - 6.2
70
6.2 - 7.9
80
7.9 - 8.8
90
8.8+
100