TCP Network Metrics
Martin Moghadam
Youssef Benarab
When the agent collects data, it considers each TCP socket connection separately. The data is then consolidated by <server-ip,server port>, where server-ip and server-port are the IP address and TCP port number of the remote computer that the agent computer has communicated with.
Parameter | Description |
|---|---|
Number of Connections | The number of connections is counted as the number of TCP packets with no data bytes and with the SYN flag set. |
Number of retransmissions | PerformanceGuard counts the number of retransmitted network packages, that is every time the client sends a packet that contains data that has previously been sent, PerformanceGuard will increment the number of retransmissions. When using the Wireshark tcp.anaylsis.retransmission filter, Wireshark only counts the first of a series of retransmitted packets. For example, if the device has three outstanding packages, and the retransmission counter expires, Wireshark will count this as a single retransmission while PerformanceGuard will count three retransmitted packets. This means that PerformanceGuard will show a higher number of retransmissions than Wireshark. The difference between the retransmission count reported by Wireshark and PerformanceGuard will vary depending on the TCP window size at the time that the retransmission occurs. You should also be aware that when you apply the tcp.analysis.retransmission filter in Wireshark, Wireshark will show packets that look like they have been retransmitted both by the client on which the measurement has been made, but also packets originating from the other end of the TCP connection. You may want to combine the tcp.analysis.retransmission filter with an ip.src.== <client> filter in order to only see transmitted packets. |
Number of connection resets | The number of packets with the TCP RST flag set. Sent as well as received packets are counted. |
Send Packets | The number of sent packets that contains TCP data. |
Send Bytes | The number of data bytes contained in the sent TCP packets. |
Send Trains | A sent train is counted when a packet that contains TCP data is received, and the previous packet that contained TCP data was received or the packet is the first one to be sent on the particular connection. For more information about trains, see TCP/IP. |
Received Packets | The number of received packets that contains TCP data. |
Received Bytes | The number of data bytes contained in the received TCP packets. |
Received Trains | A received train is counted when a packet that contains TCP data is received, and the previous packet that contained TCP data was sent. |
Total Response time | Whenever the received train counter is incremented, a response time is calculated by subtracting the time stamps of the packet at hand (received from the server) and the previous packet (sent by the client). This time is considered the individual response time for a single request. The sum of these single request response times is the Total Response Time. |
Response time histogram H0-H8 slots | Each slot contains a count of how many individual response times has fallen within the corresponding interval. The intervals are configured using the HistogramIntervals parameter. The default values [ms] of the intervals are:
|
Response time histogram H9 slot | This is a count of the requests that we sent out for which we didn't receive a response train within the time specified with the AbsResponseTimeout parameter. |
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