TCP Traffic Test

This test monitors the TCP protocol traffic to and from a server. Since most popular applications (Web servers, Citrix, Databases, Application servers, etc.) 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.

Target of the test : Any host system

Agent deploying the test : An internal agent

Outputs of the test : One set of results for each host system monitored

Configurable parameters for the test
Parameter	Description
Test Period	How often should the test be executed.
Host	The host for which the test is to be configured.
Segments_sent_min	Specify the minimum threshold for the number of segments sent/transmitted over the network. The default value is 10; in this case, the test will compute/report the TCP retransmit ratio measure only if more than 10 segments are sent over the network. On the other hand, if less than 10 segments are sent, then the test will not compute/report the TCP retransmit ratio measure. This is done to ensure that no false alerts are generated by the eG Enterprise system for the TCP retransmit ratio measure. You can change this minimum threshold to any value of your choice.
Trace	By default, this flag is set to No, indicating that detailed diagnosis is not reported by default for the Incoming Traffic and Outgoing Traffic measures of this test. However, administrators can set this flag to Yes, if detailed diagnosis should be reported for this test.
Event Capture Interval In Secs	This parameter is applicable only when the Trace flag is set to Yes. By default, the value of this parameter is set to 10 seconds. This setting ensures that the test will only capture the incoming/outgoing traffic during the last 10 seconds of the specified measurement period. Administrators can override the default value if they wish to capture the incoming/outgoing traffic for a longer duration.
High Security	This flag is applicable only when the target Linux host is monitored in the agentless manner. In highly secure environments, eG Enterprise could not perform agentless monitoring on a Linux host using SSH. To enable monitoring of the Linux hosts in such environments, set the HIGH SECURITY flag to Yes. It indicates that eG Enterprise will connect to the target Linux host in a more secure way and collect performance metrics. By default, this flag is set to No.
Detailed Diagnosis	To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option. The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled: The eG manager license should allow the detailed diagnosis capability Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.

Measurements made by the test
Measurement	Description	Measurement Unit	Interpretation
Segments received:	Indicates the rate at which segments are received by the server.	Segments/Sec
Segments sent:	Indicates the rate at which segments are sent to clients or other servers	Segments/Sec
Segment retransmissions:	Indicates the rate at which segments are being retransmitted by the server to clients/other servers	Segments/Sec
TCP retransmit ratio:	Indicates the ratio of the rate of data retransmissions to the rate of data being sent by the server to clients/other servers	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 server, an administrator can quickly be alerted to problem situations in the network link(s) to the server that may be impacting the service performance.