Product Documentation

Application Quality of Experience (QoE)

Sep 21, 2017

Network parameters such as latency, jitter and packet drop affect the user experience of HDX users. Quality of Experience (QoE) is introduced to help the users understand and check their ICA quality of experience. QoE is a calculated index, which indicates the ICA traffic performance. The users can tune the rules and policy to improve the QoE.

The QoE is a numeric value between 0–100, the higher the value the better the user experience. QoE is enabled by default for all ICA / HDX applications.

The parameters used to calculate QoE is measured between the two SD-WAN appliances at the client side and server side and not, end to end, between the sever and the client. Latency, jitter and packet drop are measured at the flow level and it could be different from the statistics at the link level. The end host (client or server) application may never know that there is a packet loss on the WAN. If the retransmit succeeds, the flow level packet loss rate is lower than the link level loss. However, as a result, it may increase latency and jitter a bit.

Default configuration for HDX traffic enables SD-WAN to re-transmit packets, thus improves the QoE index value that was lost due to packet loss in the network.

In the SD-WAN Center dashboard, you can view a graphical representation of the overall quality of HDX applications. The HDX applications are classified into the following three quality categories:

Quality QoE Range

Good

80–100

Fair

50–80

Poor

0–50

A list of the bottom five sites with the least QoE is also displayed in the NetScaler SD-WAN Center dashboard.

A graphical representation of the QoE for different time intervals allows you to monitor the performance of HDX applications at each site. 

For more information, see SD-WAN Center Dashboard.

You can also view the detailed HDX reports of each site on the NetScaler SD-WAN Center. For more information see, How to View HDX Reports.         

Note

  • Do not expect the WAN link latency, jitter, and packet drop would always match application latency, jitter and packet drop. WAN Link loss correlates to the actual WAN packet loss, while application loss is after retransmit, which is usually lower than WAN link loss. 
  •  WAN Link latency displayed in the GUI is BOWT (Best One Way Time). It is the best metrics of the link as a means to gauge the health of the link. The application QoE tracks and calculates the total and average latency of all the packets for that application. This often does not match the link BOWT.
  • When an MSI session starts, during ICA handshake , the session might be temporarily counted as 4 SSI instead of 1 MSI. After the handshake is complete, it will converge to 1 MSI. If the conversion happens before the SQL  table is updated, it may show up in ICA_Summary for that minute.
  • On session reconnect, since initial protocol information is not exchanged,  SD-WAN is not able to identify MSI, hence each connection is counted as SSI information.
  • For UDP connections, after the connection is closed, it could take up to 5 minutes for the connection to show as closed and updated in ICA_Summary. For TCP connections, after the connection is closed, it could take up to 2 minutes to show as closed in ICA_Summary.
  • QoE of TCP sessions and UDP sessions may not be the same on the same path due to the inherent different between TCP and UDP.
  • If  one user launches two virtual desktops, the number of users is countered as two.