Reporting › CA Application Delivery Analysis Views in CA Performance Center › Metrics

Metrics

When registered as a data source with CA Performance Center, CA Application Delivery Analysis views report the following metrics.

Active Sessions

Measures the number of active TCP sessions reported by a monitor feed A monitor feed is a source of response time information, such as a DNA Always Current Scheduler. that match an application/server/network combination on the management console.

Byte Loss Percentage

Measures the ratio of retransmitted data to total data, percentage of data lost on the monitored network, and loss rate in bytes per second.

Completed Sessions

Measures the number of sessions completed during a 5-minute monitoring period.

Connection Setup Time

Measures the amount of time that it takes to establish a TCP session between the client and server before data transfer can begin.

Data Transfer Time

Is a Combined metric A Combined metric indicates that an application performance problem is caused by either a server that hosts the application or a network that is communicating with the application, or both. The CA ADA management console sets a performance threshold for each of the following Combined metrics: Data Transfer Time and Transaction Time. Note that the management console does not create application incidents. However, because Combined metrics include both Network and Server metrics, the management console can rate a server or network as Minor (yellow) or Major (orange), and rate the corresponding performance impact on the application itself. For example, if a Server metric is rated as Minor, the management console can also rate a Combined metric for the application as Minor. that measures the time it takes to transmit a complete application response from the first response (the end of the Server Response Time) to the last packet sent in that request. Data Transfer Time excludes the initial server response time and includes NRTT if there is no more data to send than fits in the TCP window. The response time can be impacted by the design of the application, or the performance of the server or network. The CA Application Delivery Analysis management console does not open an incident when the Data Transfer Time threshold is crossed.

Effective Network Round Trip Time

Is a Network metric A Network metric indicates an application performance problem is caused by a network that is communicating with the application. Use the CA Application Delivery Analysis management console to customize the performance thresholds for each of the following Network metrics: Network Round Trip Time, Network Connection Time, Effective Network Round Trip Time, and Retransmission Delay. that 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. The CA Application Delivery Analysis management console opens a Network incident when the incident threshold for this metric is crossed.

Estimated Client Transaction TIme

Provides an approximation of Total Transaction Time in the absence of a Client segment. This metric is the summation of the Server segment Transaction Time and the WAN segment Network Round Trip Time. This is not an “engineering” level metric, but it can provide an indicator of the order of magnitude of response time for a given location or time of day. This metric is only available with a CA ADA 9.3 data source.

Expired Sessions

Measures the number of TCP sessions where the CA ADA Monitor service did not see the TCP session tear down (FIN or RST packet). Sessions which are inactive for a period of time are cleared out of memory and marked as Expired. The management console classifies a session as Expired if it does not observe any packets in a 15 minute period. Too many expired sessions left open can cause servers to become unresponsive.

From Server Bytes

Measures the number of bytes that were sent from a server to a client.

From Server Packets

Measures the number of packets that were sent from a server to a client.

Network Connection Time (NCT or NSCT)

Is a Network metric A Network metric indicates an application performance problem is caused by a network that is communicating with the application. Use the CA Application Delivery Analysis management console to customize the performance thresholds for each of the following Network metrics: Network Round Trip Time, Network Connection Time, Effective Network Round Trip Time, and Retransmission Delay. that measures 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. The CA Application Delivery Analysis management console opens a Network incident when the incident threshold for this metric is crossed.

Network Round Trip Time

Is a Network metric A Network metric indicates an application performance problem is caused by a network that is communicating with the application. Use the CA Application Delivery Analysis management console to customize the performance thresholds for each of the following Network metrics: Network Round Trip Time, Network Connection Time, Effective Network Round Trip Time, and Retransmission Delay. that measures the time that a packet takes to travel across the network in both directions between the server and clients on a network, excluding loss. Application, server, and client processing time are excluded. The CA Application Delivery Analysis management console opens a Network incident when the incident threshold for this metric is crossed.

Observations

The observation count measures the number of times during a 5-minute monitoring interval that a monitoring device calculated a performance metric for a particular application/server/network combination. Within a TCP transaction there can be different numbers of observations of different metrics. For example there may be more observation counts for Network Round Trip Time than Server Response Time. Other metrics are links and will always have the same number of observations. For example each TCP transaction has one Server Response Time observation and one Data Transfer Time observation. To rate a metric as Normal, Minor (yellow), or Major (orange), the metric must have a minimum number of observations.

Open Sessions

Measures the number of sessions still open at the end of the data collection period. Open sessions might become Expired or Completed during subsequent reporting intervals.

Packet Loss Percentage

Is a Network metric A Network metric indicates an application performance problem is caused by a network that is communicating with the application. Use the CA Application Delivery Analysis management console to customize the performance thresholds for each of the following Network metrics: Network Round Trip Time, Network Connection Time, Effective Network Round Trip Time, and Retransmission Delay. that measures the ratio of retransmitted data to total data within the network from the vantage point of the monitoring device which is next to the server. The monitoring device can see packets retransmitted by the server because of data losses in the server-to-client direction along the network path. When data loss occurs in the client-to-server direction (in the network path before reaching the server, for example), the monitoring device cannot observe such packet loss and that delay is not included in the Packet Loss Percentage. On the Engineering page of the CA Application Delivery Analysis management console, Packet Loss Percentage is part of the QoS report. The CA Application Delivery Analysis management console opens a Network incident when the incident threshold for this metric is crossed.

Rate from Server in Bytes

Measures the rate of data from the server in bytes.

Rate from Server in Packets

Measures the rate of data from the server in packets.

Rate to Server in Bytes

Measures the rate of data to the server in bytes.

Rate to Server in Packets

Measures the rate of data to the server in packets.

Refused Session Percentage

Is a Server metric A Server metric indicates that an application performance problem is caused by a server that hosts the application. Use the CA ADA management console to customize the performance thresholds for each of the following Server metrics: Server Response Time, Server Connection Time, Refused Session Percentage, and Unresponsive Session Percentage. that measures the percentage of connection requests the server explicitly rejected during the reporting interval. This metric is part of the Unfulfilled TCP/IP Session Requests report in the CA Application Delivery Analysis management console. The CA Application Delivery Analysis management console opens a Server incident when the incident threshold for this metric is crossed.

Refused Sessions

Measures the number of connection requests that were explicitly rejected by the server during the three-way handshake A three-way handshake, in the TCP protocol, is used to establish a connection between a client and a server. The SYN packet is sent by the client to a server to initiate the connection setup. A SYN-ACK packet is sent by the server to the client to acknowledge receipt of a SYN from the client. Finally, an ACK packet is sent by the client to the server to acknowledge receipt of a SYN-ACK from the server and to establish the TCP connection. A monitoring device uses the three-way handshake in the timing and analysis of monitored connections on the network..

Retransmission Delay

Is a Network metric A Network metric indicates an application performance problem is caused by a network that is communicating with the application. Use the CA Application Delivery Analysis management console to customize the performance thresholds for each of the following Network metrics: Network Round Trip Time, Network Connection Time, Effective Network Round Trip Time, and Retransmission Delay. that measures 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. For example, 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). The CA Application Delivery Analysis management console opens a Network incident when the incident threshold for this metric is crossed.

Retransmitted Bytes

Measures the amount of bandwidth used by retransmitted data.

Retransmitted Packets

Measures the increased load on the network infrastructure due to retransmitted packets.

Server Connection Time (SCT)

Is a Server metric A Server metric indicates that an application performance problem is caused by a server that hosts the application. Use the CA ADA management console to customize the performance thresholds for each of the following Server metrics: Server Response Time, Server Connection Time, Refused Session Percentage, and Unresponsive Session Percentage. that measures the amount of time that a server takes to acknowledge the initial client connection request by sending a Syn-Ack in response to the client’s SYN packet. The CA Application Delivery Analysis management console opens a Server incident when the incident threshold for this metric is crossed.

Server Response Time

Is a Server metric A Server metric indicates that an application performance problem is caused by a server that hosts the application. Use the CA ADA management console to customize the performance thresholds for each of the following Server metrics: Server Response Time, Server Connection Time, Refused Session Percentage, and Unresponsive Session Percentage. that measures 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 a lack of server resources such as CPU, memory, disk, or I/O, a poorly written application, or a poorly-performing tier in a multi-tier application. The CA Application Delivery Analysis management console opens a Server incident when the incident threshold for this metric is crossed.

Session Duration

Measures the duration of each TCP session.

To Server Bytes

Measures the number of bytes that were sent to a server from a client.

To Server Packets

Measures the number of packets that were sent to a server from a client.

Total Bytes

Measures the total bytes transmitted in and out.

Total Packets

Measures the total packets transmitted in and out.

Total Sessions

Indicates the total number of sessions that Completed or Expired in the sampling period. Completed Sessions + Expired Session = Total Sessions. It does not include Open, Unresponsive, or Refused sessions.

Transaction Time

Is a Combined metric A Combined metric indicates that an application performance problem is caused by either a server that hosts the application or a network that is communicating with the application, or both. The CA ADA management console sets a performance threshold for each of the following Combined metrics: Data Transfer Time and Transaction Time. Note that the management console does not create application incidents. However, because Combined metrics include both Network and Server metrics, the management console can rate a server or network as Minor (yellow) or Major (orange), and rate the corresponding performance impact on the application itself. For example, if a Server metric is rated as Minor, the management console can also rate a Combined metric for the application as Minor. that measures the amount of time elapsed from when the client sends the request to when it receives the last packet in the response. Transaction Time is the sum of Server Response Time, Network Round Trip Time, Retransmission Delay, and Data Transfer Time. The CA Application Delivery Analysis management console does not open an incident when the Transaction Time threshold is crossed.

Unresponsive Session Percentage

Is a Server metric A Server metric indicates that an application performance problem is caused by a server that hosts the application. Use the CA ADA management console to customize the performance thresholds for each of the following Server metrics: Server Response Time, Server Connection Time, Refused Session Percentage, and Unresponsive Session Percentage. that measures the percentage of sessions where a connection request was sent, but the server never responded. Part of the Unfulfilled TCP/IP Session Requests view. The CA Application Delivery Analysis management console opens a Server incident when the incident threshold for this metric is crossed.

Unresponsive Sessions

Indicates the number of sessions where a connection request was sent, but the server never responded.

User Count

Indicates the number of unique clients observed during the sample period.

User Throughput

Indicates the number of bytes transmitted divided by the time required to transmit the information.