Use First Packet Response to Understand Application Behaviour

First Packet Response (FPR) is a useful diagnostic tool, allowing you to compare the difference between the first packet time-stamp of a request flow and the first packet time-stamp of the corresponding response flow from a server. By comparing the FPR of a transaction with historical data, you can troubleshoot unusual application performance.

Application performance can be affected by many types of transaction: credit card transactions, DNS transactions, loyalty club reward transactions or any type of hosted transaction.

Ensure that First Packet Response (FPR) is enabled for each application. See Configuration > Server Subnets in the Reference Manual.

Select a site, a device or a remote branch directly from the Dashboard > Summary Device and Dashboard > Interface Summary pages. Access the Forensics report page by clicking the Drill Down icon in the Summary Devices table.

Search using the main GigaFlow Search when the site, device or remote branch is not listed. After searching by IP address, click on the Device Name in the panel on the left. The information in the panel on the right-hand side of the screen will refresh. Click Forensics in the Tools section of this panel.

Figure: Sample results from GigaFlow's search for an internal IP address

The panel on the right is displayed when the IP address is selected in the left-hand side panel.

Whether you arrive via the Dashboard or using GigaFlow Search, the Forensics report page will open with an Application Flows report.

Select Applications from the drop-down Report menu. Click the Submit icon to refresh the Forensics report page.

For demonstration purposes, we are looking for credit card related application data not displayed in the most used applications graph. To any application not listed in the top applications, change the view from graph to table.

Select 100 entries.

After identifying the application associated with credit card transactions, click the Forensics Drill Down icon to the left of the application and choose Selected from the hover option list. Click Submit again.

Select the All Fields Max FPR (First Packet Response) report type from the drop-down menu. Change the view from table to graph and click Submit .

GigaFlow will return the response times for credit card applications in the reporting period. By clicking on the graph or selecting from the calendar, you can view response times over the period. The application response times, along the y-axis, are given in milliseconds.