TCP Traffic - OS Test

Since most popular applications rely on the TCP protocol for their proper functioning, traffic monitoring at the TCP protocol layer can provide good indicators of the performance seen by the applications that use TCP. The most critical metric at the TCP protocol layer is the percentage of retransmissions. Since TCP uses an exponential back-off algorithm for its retransmissions, any retransmission of packets over the network (due to network congestion, noise, data link errors, etc.) can have a significant impact on the throughput seen by applications that use TCP. This test monitors the TCP protocol traffic to and from a virtual desktop, and particularly monitors retransmissions.

Target of the test : An Amazon Cloud Desktop Group

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each user_on_poweredondesktop

Configurable parameters for the test
Parameter	Description
Test Period	How often should the test be executed.
Host	The nick name of the Amazon Cloud Desktop Group component for which this test is to be configured.
Port	Refers to the port at which the specified host listens to. By default, this is NULL.
Inside View Using	To obtain the 'inside view' of performance of the desktops - i.e., to measure the internal performance of the cloud-based virtual desktops - this test uses a light-weight eG VM Agent software deployed on each of the desktops. Accordingly, this parameter is by default set to eG VM Agent.
Report Powered OS	If this flag is set to Yes (which is the default setting), then the 'inside view' tests will report measures for even those desktops that do not have any users logged in currently. Such desktops will be identified by their name and not by the username_on_desktopname. On the other hand, if this flag is set to No, then this test will not report measures for those desktops to which no users are logged in currently.
Report By User	This flag is set to Yes by default. The value of this flag cannot be changed. This implies that the cloud-based virtual desktops in environments will always be identified using the login name of the user. In other words, in cloud environments, this test will, by default, report measures for every username_on_desktopname.
IsCloudVMs	Since this test runs for a 'Amazon Cloud Desktop Group' component, this flag is set to Yes, by default.
Segments Sent Min	Specify the minimum threshold for the number of segments sent/transmitted over the network. The default value is 25; in this case, the test will compute/report the Retransmit ratio from system measure only if more than 25 segments are sent over the network – i.e., if the value of the Segments sent by system measure crosses the value 25. On the other hand, if the Segments sent by system measure reports a value less than 25, then the test will not compute/report the Retransmit ratio from system measure. This is done to ensure that no false alerts are generated by the eG Enterprise system for the Retransmit ratio from system measure. You can change this minimum threshold to any value of your choice.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Segments received by system	Indicates the rate at which segments are received by the guest.	Segments/Sec
Segments sent by system	Indicates the rate at which segments are sent to clients or other guests	Segments/Sec
Retransmits by system	Indicates the rate at which segments are being retransmitted by the guest	Segments/Sec
Retransmit ratio from system	Indicates the ratio of the rate of data retransmissions to the rate of data being sent by the guest	Percent	Ideally, the retransmission ratio should be low (< 5%). Most often retransmissions at the TCP layer have significant impact on application performance. Very often a large number of retransmissions are caused by a congested network link, bottlenecks at a router causing buffer/queue overflows, or by lousy network links due to poor physical layer characteristics (e.g., low signal to noise ratio). By tracking the percentage of retransmissions at a guest, an administrator can quickly be alerted to problem situations in the network link(s) to the guest that may be impacting the service performance.