Managing Performance Thresholds › How Performance Thresholds Work › How Performance Metrics Work › Network Metrics

Network Metrics

Network metrics indicate an application performance problem is caused by a network that is communicating with the application.

Network Round Trip Time

Is the amount of time that a packet takes to travel between the server and clients on a network, excluding loss. Application, server, and client processing time are excluded.

Network Connection Time

Is the amount of time between the SYN-ACK sent by the server and the ACK received back from the client. When a network is uncongested, it is a measurement of network latency that represents the minimum latency due to distance and serialization, and is the best possible round trip time for your network architecture.

Sudden spikes in this value are commonly attributed to congestion, while a plateau (which goes up and stays up) typically indicates a path change.

Effective Network Round Trip Time

Consists of Network Round Trip Time plus Retransmission Delay. Note that Retransmission Delay is not the delay due to any retransmissions; it is the average amount of retransmission delay per round trip. It is important to note that the management console is adding two averages, and is actually combining two metrics.

Retransmission Delay

Is the elapsed time between the original packet send and the last duplicate packet send. The management console reports Retransmission Delay as an average across observations and not just for the retransmitted packets. If one packet in a set of 10 requires 300 ms of retransmission time, the Retransmission Delay is reported as 30 ms (300 ms/10 packets).