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Response Time

The management console includes measurements for response times, which are averaged over 5-minute intervals, including.

Note: Definitions of these response times differ for WAN-optimized transactions.

Server Response Time

The time it takes for a server to send an initial response to a client request or the initial server "think time." Increases in the Server Response Time generally indicate the following:

• A lack of server resources such as CPU, memory, disk, or I/O
• A poorly written application

Data Transfer Time

The time it takes to transmit a complete response measured from the initial to final packet. Data Transfer Time excludes the initial server response time and includes only Network Round Trip Time if there is more data to send than fits in the TCP window.

Retransmission Delay

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).

Network Round Trip Time

The time it takes for a packet to travel across the network in both directions between the client and server.

Total Transaction Time

The time it takes to complete a TCP transaction or data request within a persistent TCP connection.

Effective Round Trip Time

Network Round Trip Time plus delays caused by retransmissions.